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linux/include/asm-generic/cmpxchg.h

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 22:07:57 +08:00
/* SPDX-License-Identifier: GPL-2.0 */
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h to simplify disintegration of asm/system.h. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-29 01:30:03 +08:00
/*
* Generic UP xchg and cmpxchg using interrupt disablement. Does not
* support SMP.
*/
Add cmpxchg_local to asm-generic for per cpu atomic operations Emulates the cmpxchg_local by disabling interrupts around variable modification. This is not reentrant wrt NMIs and MCEs. It is only protected against normal interrupts, but this is enough for architectures without such interrupt sources or if used in a context where the data is not shared with such handlers. It can be used as a fallback for architectures lacking a real cmpxchg instruction. For architectures that have a real cmpxchg but does not have NMIs or MCE, testing which of the generic vs architecture specific cmpxchg is the fastest should be done. asm-generic/cmpxchg.h defines a cmpxchg that uses cmpxchg_local. It is meant to be used as a cmpxchg fallback for architectures that do not support SMP. * Patch series comments Using cmpxchg_local shows a performance improvements of the fast path goes from a 66% speedup on a Pentium 4 to a 14% speedup on AMD64. In detail: Tested-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Measurements on a Pentium4, 3GHz, Hyperthread. SLUB Performance testing ======================== 1. Kmalloc: Repeatedly allocate then free test * slub HEAD, test 1 kmalloc(8) = 201 cycles kfree = 351 cycles kmalloc(16) = 198 cycles kfree = 359 cycles kmalloc(32) = 200 cycles kfree = 381 cycles kmalloc(64) = 224 cycles kfree = 394 cycles kmalloc(128) = 285 cycles kfree = 424 cycles kmalloc(256) = 411 cycles kfree = 546 cycles kmalloc(512) = 480 cycles kfree = 619 cycles kmalloc(1024) = 623 cycles kfree = 750 cycles kmalloc(2048) = 686 cycles kfree = 811 cycles kmalloc(4096) = 482 cycles kfree = 538 cycles kmalloc(8192) = 680 cycles kfree = 734 cycles kmalloc(16384) = 713 cycles kfree = 843 cycles * Slub HEAD, test 2 kmalloc(8) = 190 cycles kfree = 351 cycles kmalloc(16) = 195 cycles kfree = 360 cycles kmalloc(32) = 201 cycles kfree = 370 cycles kmalloc(64) = 245 cycles kfree = 389 cycles kmalloc(128) = 283 cycles kfree = 413 cycles kmalloc(256) = 409 cycles kfree = 547 cycles kmalloc(512) = 476 cycles kfree = 616 cycles kmalloc(1024) = 628 cycles kfree = 753 cycles kmalloc(2048) = 684 cycles kfree = 811 cycles kmalloc(4096) = 480 cycles kfree = 539 cycles kmalloc(8192) = 661 cycles kfree = 746 cycles kmalloc(16384) = 741 cycles kfree = 856 cycles * cmpxchg_local Slub test kmalloc(8) = 83 cycles kfree = 363 cycles kmalloc(16) = 85 cycles kfree = 372 cycles kmalloc(32) = 92 cycles kfree = 377 cycles kmalloc(64) = 115 cycles kfree = 397 cycles kmalloc(128) = 179 cycles kfree = 438 cycles kmalloc(256) = 314 cycles kfree = 564 cycles kmalloc(512) = 398 cycles kfree = 615 cycles kmalloc(1024) = 573 cycles kfree = 745 cycles kmalloc(2048) = 629 cycles kfree = 816 cycles kmalloc(4096) = 473 cycles kfree = 548 cycles kmalloc(8192) = 659 cycles kfree = 745 cycles kmalloc(16384) = 724 cycles kfree = 843 cycles 2. Kmalloc: alloc/free test * slub HEAD, test 1 kmalloc(8)/kfree = 322 cycles kmalloc(16)/kfree = 318 cycles kmalloc(32)/kfree = 318 cycles kmalloc(64)/kfree = 325 cycles kmalloc(128)/kfree = 318 cycles kmalloc(256)/kfree = 328 cycles kmalloc(512)/kfree = 328 cycles kmalloc(1024)/kfree = 328 cycles kmalloc(2048)/kfree = 328 cycles kmalloc(4096)/kfree = 678 cycles kmalloc(8192)/kfree = 1013 cycles kmalloc(16384)/kfree = 1157 cycles * Slub HEAD, test 2 kmalloc(8)/kfree = 323 cycles kmalloc(16)/kfree = 318 cycles kmalloc(32)/kfree = 318 cycles kmalloc(64)/kfree = 318 cycles kmalloc(128)/kfree = 318 cycles kmalloc(256)/kfree = 328 cycles kmalloc(512)/kfree = 328 cycles kmalloc(1024)/kfree = 328 cycles kmalloc(2048)/kfree = 328 cycles kmalloc(4096)/kfree = 648 cycles kmalloc(8192)/kfree = 1009 cycles kmalloc(16384)/kfree = 1105 cycles * cmpxchg_local Slub test kmalloc(8)/kfree = 112 cycles kmalloc(16)/kfree = 103 cycles kmalloc(32)/kfree = 103 cycles kmalloc(64)/kfree = 103 cycles kmalloc(128)/kfree = 112 cycles kmalloc(256)/kfree = 111 cycles kmalloc(512)/kfree = 111 cycles kmalloc(1024)/kfree = 111 cycles kmalloc(2048)/kfree = 121 cycles kmalloc(4096)/kfree = 650 cycles kmalloc(8192)/kfree = 1042 cycles kmalloc(16384)/kfree = 1149 cycles Tested-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Measurements on a AMD64 2.0 GHz dual-core In this test, we seem to remove 10 cycles from the kmalloc fast path. On small allocations, it gives a 14% performance increase. kfree fast path also seems to have a 10 cycles improvement. 1. Kmalloc: Repeatedly allocate then free test * cmpxchg_local slub kmalloc(8) = 63 cycles kfree = 126 cycles kmalloc(16) = 66 cycles kfree = 129 cycles kmalloc(32) = 76 cycles kfree = 138 cycles kmalloc(64) = 100 cycles kfree = 288 cycles kmalloc(128) = 128 cycles kfree = 309 cycles kmalloc(256) = 170 cycles kfree = 315 cycles kmalloc(512) = 221 cycles kfree = 357 cycles kmalloc(1024) = 324 cycles kfree = 393 cycles kmalloc(2048) = 354 cycles kfree = 440 cycles kmalloc(4096) = 394 cycles kfree = 330 cycles kmalloc(8192) = 523 cycles kfree = 481 cycles kmalloc(16384) = 643 cycles kfree = 649 cycles * Base kmalloc(8) = 74 cycles kfree = 113 cycles kmalloc(16) = 76 cycles kfree = 116 cycles kmalloc(32) = 85 cycles kfree = 133 cycles kmalloc(64) = 111 cycles kfree = 279 cycles kmalloc(128) = 138 cycles kfree = 294 cycles kmalloc(256) = 181 cycles kfree = 304 cycles kmalloc(512) = 237 cycles kfree = 327 cycles kmalloc(1024) = 340 cycles kfree = 379 cycles kmalloc(2048) = 378 cycles kfree = 433 cycles kmalloc(4096) = 399 cycles kfree = 329 cycles kmalloc(8192) = 528 cycles kfree = 624 cycles kmalloc(16384) = 651 cycles kfree = 737 cycles 2. Kmalloc: alloc/free test * cmpxchg_local slub kmalloc(8)/kfree = 96 cycles kmalloc(16)/kfree = 97 cycles kmalloc(32)/kfree = 97 cycles kmalloc(64)/kfree = 97 cycles kmalloc(128)/kfree = 97 cycles kmalloc(256)/kfree = 105 cycles kmalloc(512)/kfree = 108 cycles kmalloc(1024)/kfree = 105 cycles kmalloc(2048)/kfree = 107 cycles kmalloc(4096)/kfree = 390 cycles kmalloc(8192)/kfree = 626 cycles kmalloc(16384)/kfree = 662 cycles * Base kmalloc(8)/kfree = 116 cycles kmalloc(16)/kfree = 116 cycles kmalloc(32)/kfree = 116 cycles kmalloc(64)/kfree = 116 cycles kmalloc(128)/kfree = 116 cycles kmalloc(256)/kfree = 126 cycles kmalloc(512)/kfree = 126 cycles kmalloc(1024)/kfree = 126 cycles kmalloc(2048)/kfree = 126 cycles kmalloc(4096)/kfree = 384 cycles kmalloc(8192)/kfree = 749 cycles kmalloc(16384)/kfree = 786 cycles Tested-by: Christoph Lameter <clameter@sgi.com> I can confirm Mathieus' measurement now: Athlon64: regular NUMA/discontig 1. Kmalloc: Repeatedly allocate then free test 10000 times kmalloc(8) -> 79 cycles kfree -> 92 cycles 10000 times kmalloc(16) -> 79 cycles kfree -> 93 cycles 10000 times kmalloc(32) -> 88 cycles kfree -> 95 cycles 10000 times kmalloc(64) -> 124 cycles kfree -> 132 cycles 10000 times kmalloc(128) -> 157 cycles kfree -> 247 cycles 10000 times kmalloc(256) -> 200 cycles kfree -> 257 cycles 10000 times kmalloc(512) -> 250 cycles kfree -> 277 cycles 10000 times kmalloc(1024) -> 337 cycles kfree -> 314 cycles 10000 times kmalloc(2048) -> 365 cycles kfree -> 330 cycles 10000 times kmalloc(4096) -> 352 cycles kfree -> 240 cycles 10000 times kmalloc(8192) -> 456 cycles kfree -> 340 cycles 10000 times kmalloc(16384) -> 646 cycles kfree -> 471 cycles 2. Kmalloc: alloc/free test 10000 times kmalloc(8)/kfree -> 124 cycles 10000 times kmalloc(16)/kfree -> 124 cycles 10000 times kmalloc(32)/kfree -> 124 cycles 10000 times kmalloc(64)/kfree -> 124 cycles 10000 times kmalloc(128)/kfree -> 124 cycles 10000 times kmalloc(256)/kfree -> 132 cycles 10000 times kmalloc(512)/kfree -> 132 cycles 10000 times kmalloc(1024)/kfree -> 132 cycles 10000 times kmalloc(2048)/kfree -> 132 cycles 10000 times kmalloc(4096)/kfree -> 319 cycles 10000 times kmalloc(8192)/kfree -> 486 cycles 10000 times kmalloc(16384)/kfree -> 539 cycles cmpxchg_local NUMA/discontig 1. Kmalloc: Repeatedly allocate then free test 10000 times kmalloc(8) -> 55 cycles kfree -> 90 cycles 10000 times kmalloc(16) -> 55 cycles kfree -> 92 cycles 10000 times kmalloc(32) -> 70 cycles kfree -> 91 cycles 10000 times kmalloc(64) -> 100 cycles kfree -> 141 cycles 10000 times kmalloc(128) -> 128 cycles kfree -> 233 cycles 10000 times kmalloc(256) -> 172 cycles kfree -> 251 cycles 10000 times kmalloc(512) -> 225 cycles kfree -> 275 cycles 10000 times kmalloc(1024) -> 325 cycles kfree -> 311 cycles 10000 times kmalloc(2048) -> 346 cycles kfree -> 330 cycles 10000 times kmalloc(4096) -> 351 cycles kfree -> 238 cycles 10000 times kmalloc(8192) -> 450 cycles kfree -> 342 cycles 10000 times kmalloc(16384) -> 630 cycles kfree -> 546 cycles 2. Kmalloc: alloc/free test 10000 times kmalloc(8)/kfree -> 81 cycles 10000 times kmalloc(16)/kfree -> 81 cycles 10000 times kmalloc(32)/kfree -> 81 cycles 10000 times kmalloc(64)/kfree -> 81 cycles 10000 times kmalloc(128)/kfree -> 81 cycles 10000 times kmalloc(256)/kfree -> 91 cycles 10000 times kmalloc(512)/kfree -> 90 cycles 10000 times kmalloc(1024)/kfree -> 91 cycles 10000 times kmalloc(2048)/kfree -> 90 cycles 10000 times kmalloc(4096)/kfree -> 318 cycles 10000 times kmalloc(8192)/kfree -> 483 cycles 10000 times kmalloc(16384)/kfree -> 536 cycles Changelog: - Ran though checkpatch. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-07 16:16:07 +08:00
#ifndef __ASM_GENERIC_CMPXCHG_H
#define __ASM_GENERIC_CMPXCHG_H
#ifdef CONFIG_SMP
#error "Cannot use generic cmpxchg on SMP"
#endif
asm-generic: add linux/types.h to cmpxchg.h Builds of the openrisc or1ksim_defconfig show the following: In file included from arch/openrisc/include/generated/asm/cmpxchg.h:1:0, from include/asm-generic/atomic.h:18, from arch/openrisc/include/generated/asm/atomic.h:1, from include/linux/atomic.h:4, from include/linux/dcache.h:4, from fs/notify/fsnotify.c:19: include/asm-generic/cmpxchg.h: In function '__xchg': include/asm-generic/cmpxchg.h:34:20: error: expected ')' before 'u8' include/asm-generic/cmpxchg.h:34:20: warning: type defaults to 'int' in type name and many more lines of similar errors. It seems specific to the or32 because most other platforms have an arch specific component that would have already included types.h ahead of time, but the o32 does not. Cc: Arnd Bergmann <arnd@arndb.de> Cc: Jonas Bonn <jonas@southpole.se> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Acked-by: David Howells <dhowells@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-04-02 04:38:47 +08:00
#include <linux/types.h>
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h to simplify disintegration of asm/system.h. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-29 01:30:03 +08:00
#include <linux/irqflags.h>
/*
* This function doesn't exist, so you'll get a linker error if
* something tries to do an invalidly-sized xchg().
*/
locking/atomic: cmpxchg: support ARCH_ATOMIC We'd like all architectures to convert to ARCH_ATOMIC, as this will enable functionality, and once all architectures are converted it will be possible to make significant cleanups to the atomic headers. A number of architectures use asm-generic/cmpxchg.h or asm-generic/cmpxhg-local.h, and it's impractical to convert the headers and all these architectures in one go. To make it possible to convert them one-by-one, let's make the asm-generic implementation function as either cmpxchg*() or arch_cmpxchg*() depending on whether ARCH_ATOMIC is selected. To do this, the generic implementations are prefixed as generic_cmpxchg_*(), and preprocessor definitions map cmpxchg_*()/arch_cmpxchg_*() onto these as appropriate. Once all users are moved over to ARCH_ATOMIC the ifdeffery in the header can be simplified and/or removed entirely. For existing users (none of which select ARCH_ATOMIC), there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210525140232.53872-13-mark.rutland@arm.com
2021-05-25 22:02:11 +08:00
extern void __generic_xchg_called_with_bad_pointer(void);
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h to simplify disintegration of asm/system.h. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-29 01:30:03 +08:00
static inline
locking/atomic: cmpxchg: support ARCH_ATOMIC We'd like all architectures to convert to ARCH_ATOMIC, as this will enable functionality, and once all architectures are converted it will be possible to make significant cleanups to the atomic headers. A number of architectures use asm-generic/cmpxchg.h or asm-generic/cmpxhg-local.h, and it's impractical to convert the headers and all these architectures in one go. To make it possible to convert them one-by-one, let's make the asm-generic implementation function as either cmpxchg*() or arch_cmpxchg*() depending on whether ARCH_ATOMIC is selected. To do this, the generic implementations are prefixed as generic_cmpxchg_*(), and preprocessor definitions map cmpxchg_*()/arch_cmpxchg_*() onto these as appropriate. Once all users are moved over to ARCH_ATOMIC the ifdeffery in the header can be simplified and/or removed entirely. For existing users (none of which select ARCH_ATOMIC), there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210525140232.53872-13-mark.rutland@arm.com
2021-05-25 22:02:11 +08:00
unsigned long __generic_xchg(unsigned long x, volatile void *ptr, int size)
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h to simplify disintegration of asm/system.h. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-29 01:30:03 +08:00
{
unsigned long ret, flags;
switch (size) {
case 1:
#ifdef __xchg_u8
return __xchg_u8(x, ptr);
#else
local_irq_save(flags);
ret = *(volatile u8 *)ptr;
asm-generic: avoid __generic_cmpxchg_local warnings Code that passes a 32-bit constant into cmpxchg() produces a harmless sparse warning because of the truncation in the branch that is not taken: fs/erofs/zdata.c: note: in included file (through /home/arnd/arm-soc/arch/arm/include/asm/cmpxchg.h, /home/arnd/arm-soc/arch/arm/include/asm/atomic.h, /home/arnd/arm-soc/include/linux/atomic.h, ...): include/asm-generic/cmpxchg-local.h:29:33: warning: cast truncates bits from constant value (5f0ecafe becomes fe) include/asm-generic/cmpxchg-local.h:33:34: warning: cast truncates bits from constant value (5f0ecafe becomes cafe) include/asm-generic/cmpxchg-local.h:29:33: warning: cast truncates bits from constant value (5f0ecafe becomes fe) include/asm-generic/cmpxchg-local.h:30:42: warning: cast truncates bits from constant value (5f0edead becomes ad) include/asm-generic/cmpxchg-local.h:33:34: warning: cast truncates bits from constant value (5f0ecafe becomes cafe) include/asm-generic/cmpxchg-local.h:34:44: warning: cast truncates bits from constant value (5f0edead becomes dead) This was reported as a regression to Matt's recent __generic_cmpxchg_local patch, though this patch only added more warnings on top of the ones that were already there. Rewording the truncation to use an explicit bitmask instead of a cast to a smaller type avoids the warning but otherwise leaves the code unchanged. I had another look at why the cast is even needed for atomic_cmpxchg(), and as Matt describes the problem here is that atomic_t contains a signed 'int', but cmpxchg() takes an 'unsigned long' argument, and converting between the two leads to a 64-bit sign-extension of negative 32-bit atomics. I checked the other implementations of arch_cmpxchg() and did not find any others that run into the same problem as __generic_cmpxchg_local(), but it's easy to be on the safe side here and always convert the signed int into an unsigned int when calling arch_cmpxchg(), as this will work even when any of the arch_cmpxchg() implementations run into the same problem. Fixes: 624654152284 ("locking/atomic: cmpxchg: Make __generic_cmpxchg_local compare against zero-extended 'old' value") Reviewed-by: Matt Evans <mev@rivosinc.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2023-03-02 16:53:31 +08:00
*(volatile u8 *)ptr = (x & 0xffu);
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h to simplify disintegration of asm/system.h. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-29 01:30:03 +08:00
local_irq_restore(flags);
return ret;
#endif /* __xchg_u8 */
case 2:
#ifdef __xchg_u16
return __xchg_u16(x, ptr);
#else
local_irq_save(flags);
ret = *(volatile u16 *)ptr;
asm-generic: avoid __generic_cmpxchg_local warnings Code that passes a 32-bit constant into cmpxchg() produces a harmless sparse warning because of the truncation in the branch that is not taken: fs/erofs/zdata.c: note: in included file (through /home/arnd/arm-soc/arch/arm/include/asm/cmpxchg.h, /home/arnd/arm-soc/arch/arm/include/asm/atomic.h, /home/arnd/arm-soc/include/linux/atomic.h, ...): include/asm-generic/cmpxchg-local.h:29:33: warning: cast truncates bits from constant value (5f0ecafe becomes fe) include/asm-generic/cmpxchg-local.h:33:34: warning: cast truncates bits from constant value (5f0ecafe becomes cafe) include/asm-generic/cmpxchg-local.h:29:33: warning: cast truncates bits from constant value (5f0ecafe becomes fe) include/asm-generic/cmpxchg-local.h:30:42: warning: cast truncates bits from constant value (5f0edead becomes ad) include/asm-generic/cmpxchg-local.h:33:34: warning: cast truncates bits from constant value (5f0ecafe becomes cafe) include/asm-generic/cmpxchg-local.h:34:44: warning: cast truncates bits from constant value (5f0edead becomes dead) This was reported as a regression to Matt's recent __generic_cmpxchg_local patch, though this patch only added more warnings on top of the ones that were already there. Rewording the truncation to use an explicit bitmask instead of a cast to a smaller type avoids the warning but otherwise leaves the code unchanged. I had another look at why the cast is even needed for atomic_cmpxchg(), and as Matt describes the problem here is that atomic_t contains a signed 'int', but cmpxchg() takes an 'unsigned long' argument, and converting between the two leads to a 64-bit sign-extension of negative 32-bit atomics. I checked the other implementations of arch_cmpxchg() and did not find any others that run into the same problem as __generic_cmpxchg_local(), but it's easy to be on the safe side here and always convert the signed int into an unsigned int when calling arch_cmpxchg(), as this will work even when any of the arch_cmpxchg() implementations run into the same problem. Fixes: 624654152284 ("locking/atomic: cmpxchg: Make __generic_cmpxchg_local compare against zero-extended 'old' value") Reviewed-by: Matt Evans <mev@rivosinc.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2023-03-02 16:53:31 +08:00
*(volatile u16 *)ptr = (x & 0xffffu);
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h to simplify disintegration of asm/system.h. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-29 01:30:03 +08:00
local_irq_restore(flags);
return ret;
#endif /* __xchg_u16 */
case 4:
#ifdef __xchg_u32
return __xchg_u32(x, ptr);
#else
local_irq_save(flags);
ret = *(volatile u32 *)ptr;
asm-generic: avoid __generic_cmpxchg_local warnings Code that passes a 32-bit constant into cmpxchg() produces a harmless sparse warning because of the truncation in the branch that is not taken: fs/erofs/zdata.c: note: in included file (through /home/arnd/arm-soc/arch/arm/include/asm/cmpxchg.h, /home/arnd/arm-soc/arch/arm/include/asm/atomic.h, /home/arnd/arm-soc/include/linux/atomic.h, ...): include/asm-generic/cmpxchg-local.h:29:33: warning: cast truncates bits from constant value (5f0ecafe becomes fe) include/asm-generic/cmpxchg-local.h:33:34: warning: cast truncates bits from constant value (5f0ecafe becomes cafe) include/asm-generic/cmpxchg-local.h:29:33: warning: cast truncates bits from constant value (5f0ecafe becomes fe) include/asm-generic/cmpxchg-local.h:30:42: warning: cast truncates bits from constant value (5f0edead becomes ad) include/asm-generic/cmpxchg-local.h:33:34: warning: cast truncates bits from constant value (5f0ecafe becomes cafe) include/asm-generic/cmpxchg-local.h:34:44: warning: cast truncates bits from constant value (5f0edead becomes dead) This was reported as a regression to Matt's recent __generic_cmpxchg_local patch, though this patch only added more warnings on top of the ones that were already there. Rewording the truncation to use an explicit bitmask instead of a cast to a smaller type avoids the warning but otherwise leaves the code unchanged. I had another look at why the cast is even needed for atomic_cmpxchg(), and as Matt describes the problem here is that atomic_t contains a signed 'int', but cmpxchg() takes an 'unsigned long' argument, and converting between the two leads to a 64-bit sign-extension of negative 32-bit atomics. I checked the other implementations of arch_cmpxchg() and did not find any others that run into the same problem as __generic_cmpxchg_local(), but it's easy to be on the safe side here and always convert the signed int into an unsigned int when calling arch_cmpxchg(), as this will work even when any of the arch_cmpxchg() implementations run into the same problem. Fixes: 624654152284 ("locking/atomic: cmpxchg: Make __generic_cmpxchg_local compare against zero-extended 'old' value") Reviewed-by: Matt Evans <mev@rivosinc.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2023-03-02 16:53:31 +08:00
*(volatile u32 *)ptr = (x & 0xffffffffu);
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h to simplify disintegration of asm/system.h. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-29 01:30:03 +08:00
local_irq_restore(flags);
return ret;
#endif /* __xchg_u32 */
#ifdef CONFIG_64BIT
case 8:
#ifdef __xchg_u64
return __xchg_u64(x, ptr);
#else
local_irq_save(flags);
ret = *(volatile u64 *)ptr;
*(volatile u64 *)ptr = x;
local_irq_restore(flags);
return ret;
#endif /* __xchg_u64 */
#endif /* CONFIG_64BIT */
default:
locking/atomic: cmpxchg: support ARCH_ATOMIC We'd like all architectures to convert to ARCH_ATOMIC, as this will enable functionality, and once all architectures are converted it will be possible to make significant cleanups to the atomic headers. A number of architectures use asm-generic/cmpxchg.h or asm-generic/cmpxhg-local.h, and it's impractical to convert the headers and all these architectures in one go. To make it possible to convert them one-by-one, let's make the asm-generic implementation function as either cmpxchg*() or arch_cmpxchg*() depending on whether ARCH_ATOMIC is selected. To do this, the generic implementations are prefixed as generic_cmpxchg_*(), and preprocessor definitions map cmpxchg_*()/arch_cmpxchg_*() onto these as appropriate. Once all users are moved over to ARCH_ATOMIC the ifdeffery in the header can be simplified and/or removed entirely. For existing users (none of which select ARCH_ATOMIC), there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210525140232.53872-13-mark.rutland@arm.com
2021-05-25 22:02:11 +08:00
__generic_xchg_called_with_bad_pointer();
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h to simplify disintegration of asm/system.h. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-29 01:30:03 +08:00
return x;
}
}
locking/atomic: cmpxchg: support ARCH_ATOMIC We'd like all architectures to convert to ARCH_ATOMIC, as this will enable functionality, and once all architectures are converted it will be possible to make significant cleanups to the atomic headers. A number of architectures use asm-generic/cmpxchg.h or asm-generic/cmpxhg-local.h, and it's impractical to convert the headers and all these architectures in one go. To make it possible to convert them one-by-one, let's make the asm-generic implementation function as either cmpxchg*() or arch_cmpxchg*() depending on whether ARCH_ATOMIC is selected. To do this, the generic implementations are prefixed as generic_cmpxchg_*(), and preprocessor definitions map cmpxchg_*()/arch_cmpxchg_*() onto these as appropriate. Once all users are moved over to ARCH_ATOMIC the ifdeffery in the header can be simplified and/or removed entirely. For existing users (none of which select ARCH_ATOMIC), there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210525140232.53872-13-mark.rutland@arm.com
2021-05-25 22:02:11 +08:00
#define generic_xchg(ptr, x) ({ \
((__typeof__(*(ptr))) \
__generic_xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))); \
asm-generic: cmpxchg: avoid warnings from macro-ized cmpxchg() implementations This change is similar to e001bbae7147b111fe1aa42beaf835635f3c016e ARM: cmpxchg: avoid warnings from macro-ized cmpxchg() implementations A recent change in kernel/acct.c added a new warning for many configurations using generic __xchg() implementation: In file included from ./arch/nios2/include/asm/cmpxchg.h:12:0, from include/asm-generic/atomic.h:18, from arch/nios2/include/generated/asm/atomic.h:1, from include/linux/atomic.h:4, from include/linux/spinlock.h:406, from include/linux/mmzone.h:7, from include/linux/gfp.h:5, from include/linux/mm.h:9, from kernel/acct.c:46: kernel/acct.c: In function 'acct_pin_kill': include/asm-generic/cmpxchg.h:94:3: warning: value computed is not used [-Wunused-value] ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ ^ include/asm-generic/cmpxchg.h:102:28: note: in expansion of macro 'cmpxchg_local' #define cmpxchg(ptr, o, n) cmpxchg_local((ptr), (o), (n)) ^ kernel/acct.c:177:2: note: in expansion of macro 'cmpxchg' cmpxchg(&acct->ns->bacct, pin, NULL); ^ The code is in fact correct, it's just a cmpxchg() call that intentionally ignores the result, and no other code does that. The warning does not show up on x86 because of the way that its cmpxchg() macro is written. This changes the asm-ggeneric implementation to use a similar construct with a compound expression instead of a typecast, which causes the compiler to not complain about an unused result. Fix the other macros in this file in a similar way, and place them just below their function implementations. Signed-off-by: Marek Vasut <marex@denx.de> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2015-09-19 12:42:21 +08:00
})
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h to simplify disintegration of asm/system.h. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-29 01:30:03 +08:00
Add cmpxchg_local to asm-generic for per cpu atomic operations Emulates the cmpxchg_local by disabling interrupts around variable modification. This is not reentrant wrt NMIs and MCEs. It is only protected against normal interrupts, but this is enough for architectures without such interrupt sources or if used in a context where the data is not shared with such handlers. It can be used as a fallback for architectures lacking a real cmpxchg instruction. For architectures that have a real cmpxchg but does not have NMIs or MCE, testing which of the generic vs architecture specific cmpxchg is the fastest should be done. asm-generic/cmpxchg.h defines a cmpxchg that uses cmpxchg_local. It is meant to be used as a cmpxchg fallback for architectures that do not support SMP. * Patch series comments Using cmpxchg_local shows a performance improvements of the fast path goes from a 66% speedup on a Pentium 4 to a 14% speedup on AMD64. In detail: Tested-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Measurements on a Pentium4, 3GHz, Hyperthread. SLUB Performance testing ======================== 1. Kmalloc: Repeatedly allocate then free test * slub HEAD, test 1 kmalloc(8) = 201 cycles kfree = 351 cycles kmalloc(16) = 198 cycles kfree = 359 cycles kmalloc(32) = 200 cycles kfree = 381 cycles kmalloc(64) = 224 cycles kfree = 394 cycles kmalloc(128) = 285 cycles kfree = 424 cycles kmalloc(256) = 411 cycles kfree = 546 cycles kmalloc(512) = 480 cycles kfree = 619 cycles kmalloc(1024) = 623 cycles kfree = 750 cycles kmalloc(2048) = 686 cycles kfree = 811 cycles kmalloc(4096) = 482 cycles kfree = 538 cycles kmalloc(8192) = 680 cycles kfree = 734 cycles kmalloc(16384) = 713 cycles kfree = 843 cycles * Slub HEAD, test 2 kmalloc(8) = 190 cycles kfree = 351 cycles kmalloc(16) = 195 cycles kfree = 360 cycles kmalloc(32) = 201 cycles kfree = 370 cycles kmalloc(64) = 245 cycles kfree = 389 cycles kmalloc(128) = 283 cycles kfree = 413 cycles kmalloc(256) = 409 cycles kfree = 547 cycles kmalloc(512) = 476 cycles kfree = 616 cycles kmalloc(1024) = 628 cycles kfree = 753 cycles kmalloc(2048) = 684 cycles kfree = 811 cycles kmalloc(4096) = 480 cycles kfree = 539 cycles kmalloc(8192) = 661 cycles kfree = 746 cycles kmalloc(16384) = 741 cycles kfree = 856 cycles * cmpxchg_local Slub test kmalloc(8) = 83 cycles kfree = 363 cycles kmalloc(16) = 85 cycles kfree = 372 cycles kmalloc(32) = 92 cycles kfree = 377 cycles kmalloc(64) = 115 cycles kfree = 397 cycles kmalloc(128) = 179 cycles kfree = 438 cycles kmalloc(256) = 314 cycles kfree = 564 cycles kmalloc(512) = 398 cycles kfree = 615 cycles kmalloc(1024) = 573 cycles kfree = 745 cycles kmalloc(2048) = 629 cycles kfree = 816 cycles kmalloc(4096) = 473 cycles kfree = 548 cycles kmalloc(8192) = 659 cycles kfree = 745 cycles kmalloc(16384) = 724 cycles kfree = 843 cycles 2. Kmalloc: alloc/free test * slub HEAD, test 1 kmalloc(8)/kfree = 322 cycles kmalloc(16)/kfree = 318 cycles kmalloc(32)/kfree = 318 cycles kmalloc(64)/kfree = 325 cycles kmalloc(128)/kfree = 318 cycles kmalloc(256)/kfree = 328 cycles kmalloc(512)/kfree = 328 cycles kmalloc(1024)/kfree = 328 cycles kmalloc(2048)/kfree = 328 cycles kmalloc(4096)/kfree = 678 cycles kmalloc(8192)/kfree = 1013 cycles kmalloc(16384)/kfree = 1157 cycles * Slub HEAD, test 2 kmalloc(8)/kfree = 323 cycles kmalloc(16)/kfree = 318 cycles kmalloc(32)/kfree = 318 cycles kmalloc(64)/kfree = 318 cycles kmalloc(128)/kfree = 318 cycles kmalloc(256)/kfree = 328 cycles kmalloc(512)/kfree = 328 cycles kmalloc(1024)/kfree = 328 cycles kmalloc(2048)/kfree = 328 cycles kmalloc(4096)/kfree = 648 cycles kmalloc(8192)/kfree = 1009 cycles kmalloc(16384)/kfree = 1105 cycles * cmpxchg_local Slub test kmalloc(8)/kfree = 112 cycles kmalloc(16)/kfree = 103 cycles kmalloc(32)/kfree = 103 cycles kmalloc(64)/kfree = 103 cycles kmalloc(128)/kfree = 112 cycles kmalloc(256)/kfree = 111 cycles kmalloc(512)/kfree = 111 cycles kmalloc(1024)/kfree = 111 cycles kmalloc(2048)/kfree = 121 cycles kmalloc(4096)/kfree = 650 cycles kmalloc(8192)/kfree = 1042 cycles kmalloc(16384)/kfree = 1149 cycles Tested-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Measurements on a AMD64 2.0 GHz dual-core In this test, we seem to remove 10 cycles from the kmalloc fast path. On small allocations, it gives a 14% performance increase. kfree fast path also seems to have a 10 cycles improvement. 1. Kmalloc: Repeatedly allocate then free test * cmpxchg_local slub kmalloc(8) = 63 cycles kfree = 126 cycles kmalloc(16) = 66 cycles kfree = 129 cycles kmalloc(32) = 76 cycles kfree = 138 cycles kmalloc(64) = 100 cycles kfree = 288 cycles kmalloc(128) = 128 cycles kfree = 309 cycles kmalloc(256) = 170 cycles kfree = 315 cycles kmalloc(512) = 221 cycles kfree = 357 cycles kmalloc(1024) = 324 cycles kfree = 393 cycles kmalloc(2048) = 354 cycles kfree = 440 cycles kmalloc(4096) = 394 cycles kfree = 330 cycles kmalloc(8192) = 523 cycles kfree = 481 cycles kmalloc(16384) = 643 cycles kfree = 649 cycles * Base kmalloc(8) = 74 cycles kfree = 113 cycles kmalloc(16) = 76 cycles kfree = 116 cycles kmalloc(32) = 85 cycles kfree = 133 cycles kmalloc(64) = 111 cycles kfree = 279 cycles kmalloc(128) = 138 cycles kfree = 294 cycles kmalloc(256) = 181 cycles kfree = 304 cycles kmalloc(512) = 237 cycles kfree = 327 cycles kmalloc(1024) = 340 cycles kfree = 379 cycles kmalloc(2048) = 378 cycles kfree = 433 cycles kmalloc(4096) = 399 cycles kfree = 329 cycles kmalloc(8192) = 528 cycles kfree = 624 cycles kmalloc(16384) = 651 cycles kfree = 737 cycles 2. Kmalloc: alloc/free test * cmpxchg_local slub kmalloc(8)/kfree = 96 cycles kmalloc(16)/kfree = 97 cycles kmalloc(32)/kfree = 97 cycles kmalloc(64)/kfree = 97 cycles kmalloc(128)/kfree = 97 cycles kmalloc(256)/kfree = 105 cycles kmalloc(512)/kfree = 108 cycles kmalloc(1024)/kfree = 105 cycles kmalloc(2048)/kfree = 107 cycles kmalloc(4096)/kfree = 390 cycles kmalloc(8192)/kfree = 626 cycles kmalloc(16384)/kfree = 662 cycles * Base kmalloc(8)/kfree = 116 cycles kmalloc(16)/kfree = 116 cycles kmalloc(32)/kfree = 116 cycles kmalloc(64)/kfree = 116 cycles kmalloc(128)/kfree = 116 cycles kmalloc(256)/kfree = 126 cycles kmalloc(512)/kfree = 126 cycles kmalloc(1024)/kfree = 126 cycles kmalloc(2048)/kfree = 126 cycles kmalloc(4096)/kfree = 384 cycles kmalloc(8192)/kfree = 749 cycles kmalloc(16384)/kfree = 786 cycles Tested-by: Christoph Lameter <clameter@sgi.com> I can confirm Mathieus' measurement now: Athlon64: regular NUMA/discontig 1. Kmalloc: Repeatedly allocate then free test 10000 times kmalloc(8) -> 79 cycles kfree -> 92 cycles 10000 times kmalloc(16) -> 79 cycles kfree -> 93 cycles 10000 times kmalloc(32) -> 88 cycles kfree -> 95 cycles 10000 times kmalloc(64) -> 124 cycles kfree -> 132 cycles 10000 times kmalloc(128) -> 157 cycles kfree -> 247 cycles 10000 times kmalloc(256) -> 200 cycles kfree -> 257 cycles 10000 times kmalloc(512) -> 250 cycles kfree -> 277 cycles 10000 times kmalloc(1024) -> 337 cycles kfree -> 314 cycles 10000 times kmalloc(2048) -> 365 cycles kfree -> 330 cycles 10000 times kmalloc(4096) -> 352 cycles kfree -> 240 cycles 10000 times kmalloc(8192) -> 456 cycles kfree -> 340 cycles 10000 times kmalloc(16384) -> 646 cycles kfree -> 471 cycles 2. Kmalloc: alloc/free test 10000 times kmalloc(8)/kfree -> 124 cycles 10000 times kmalloc(16)/kfree -> 124 cycles 10000 times kmalloc(32)/kfree -> 124 cycles 10000 times kmalloc(64)/kfree -> 124 cycles 10000 times kmalloc(128)/kfree -> 124 cycles 10000 times kmalloc(256)/kfree -> 132 cycles 10000 times kmalloc(512)/kfree -> 132 cycles 10000 times kmalloc(1024)/kfree -> 132 cycles 10000 times kmalloc(2048)/kfree -> 132 cycles 10000 times kmalloc(4096)/kfree -> 319 cycles 10000 times kmalloc(8192)/kfree -> 486 cycles 10000 times kmalloc(16384)/kfree -> 539 cycles cmpxchg_local NUMA/discontig 1. Kmalloc: Repeatedly allocate then free test 10000 times kmalloc(8) -> 55 cycles kfree -> 90 cycles 10000 times kmalloc(16) -> 55 cycles kfree -> 92 cycles 10000 times kmalloc(32) -> 70 cycles kfree -> 91 cycles 10000 times kmalloc(64) -> 100 cycles kfree -> 141 cycles 10000 times kmalloc(128) -> 128 cycles kfree -> 233 cycles 10000 times kmalloc(256) -> 172 cycles kfree -> 251 cycles 10000 times kmalloc(512) -> 225 cycles kfree -> 275 cycles 10000 times kmalloc(1024) -> 325 cycles kfree -> 311 cycles 10000 times kmalloc(2048) -> 346 cycles kfree -> 330 cycles 10000 times kmalloc(4096) -> 351 cycles kfree -> 238 cycles 10000 times kmalloc(8192) -> 450 cycles kfree -> 342 cycles 10000 times kmalloc(16384) -> 630 cycles kfree -> 546 cycles 2. Kmalloc: alloc/free test 10000 times kmalloc(8)/kfree -> 81 cycles 10000 times kmalloc(16)/kfree -> 81 cycles 10000 times kmalloc(32)/kfree -> 81 cycles 10000 times kmalloc(64)/kfree -> 81 cycles 10000 times kmalloc(128)/kfree -> 81 cycles 10000 times kmalloc(256)/kfree -> 91 cycles 10000 times kmalloc(512)/kfree -> 90 cycles 10000 times kmalloc(1024)/kfree -> 91 cycles 10000 times kmalloc(2048)/kfree -> 90 cycles 10000 times kmalloc(4096)/kfree -> 318 cycles 10000 times kmalloc(8192)/kfree -> 483 cycles 10000 times kmalloc(16384)/kfree -> 536 cycles Changelog: - Ran though checkpatch. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-07 16:16:07 +08:00
/*
* Atomic compare and exchange.
*/
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h to simplify disintegration of asm/system.h. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-29 01:30:03 +08:00
#include <asm-generic/cmpxchg-local.h>
locking/atomic: cmpxchg: support ARCH_ATOMIC We'd like all architectures to convert to ARCH_ATOMIC, as this will enable functionality, and once all architectures are converted it will be possible to make significant cleanups to the atomic headers. A number of architectures use asm-generic/cmpxchg.h or asm-generic/cmpxhg-local.h, and it's impractical to convert the headers and all these architectures in one go. To make it possible to convert them one-by-one, let's make the asm-generic implementation function as either cmpxchg*() or arch_cmpxchg*() depending on whether ARCH_ATOMIC is selected. To do this, the generic implementations are prefixed as generic_cmpxchg_*(), and preprocessor definitions map cmpxchg_*()/arch_cmpxchg_*() onto these as appropriate. Once all users are moved over to ARCH_ATOMIC the ifdeffery in the header can be simplified and/or removed entirely. For existing users (none of which select ARCH_ATOMIC), there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210525140232.53872-13-mark.rutland@arm.com
2021-05-25 22:02:11 +08:00
#define generic_cmpxchg_local(ptr, o, n) ({ \
((__typeof__(*(ptr)))__generic_cmpxchg_local((ptr), (unsigned long)(o), \
(unsigned long)(n), sizeof(*(ptr)))); \
asm-generic: cmpxchg: avoid warnings from macro-ized cmpxchg() implementations This change is similar to e001bbae7147b111fe1aa42beaf835635f3c016e ARM: cmpxchg: avoid warnings from macro-ized cmpxchg() implementations A recent change in kernel/acct.c added a new warning for many configurations using generic __xchg() implementation: In file included from ./arch/nios2/include/asm/cmpxchg.h:12:0, from include/asm-generic/atomic.h:18, from arch/nios2/include/generated/asm/atomic.h:1, from include/linux/atomic.h:4, from include/linux/spinlock.h:406, from include/linux/mmzone.h:7, from include/linux/gfp.h:5, from include/linux/mm.h:9, from kernel/acct.c:46: kernel/acct.c: In function 'acct_pin_kill': include/asm-generic/cmpxchg.h:94:3: warning: value computed is not used [-Wunused-value] ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ ^ include/asm-generic/cmpxchg.h:102:28: note: in expansion of macro 'cmpxchg_local' #define cmpxchg(ptr, o, n) cmpxchg_local((ptr), (o), (n)) ^ kernel/acct.c:177:2: note: in expansion of macro 'cmpxchg' cmpxchg(&acct->ns->bacct, pin, NULL); ^ The code is in fact correct, it's just a cmpxchg() call that intentionally ignores the result, and no other code does that. The warning does not show up on x86 because of the way that its cmpxchg() macro is written. This changes the asm-ggeneric implementation to use a similar construct with a compound expression instead of a typecast, which causes the compiler to not complain about an unused result. Fix the other macros in this file in a similar way, and place them just below their function implementations. Signed-off-by: Marek Vasut <marex@denx.de> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2015-09-19 12:42:21 +08:00
})
locking/atomic: cmpxchg: support ARCH_ATOMIC We'd like all architectures to convert to ARCH_ATOMIC, as this will enable functionality, and once all architectures are converted it will be possible to make significant cleanups to the atomic headers. A number of architectures use asm-generic/cmpxchg.h or asm-generic/cmpxhg-local.h, and it's impractical to convert the headers and all these architectures in one go. To make it possible to convert them one-by-one, let's make the asm-generic implementation function as either cmpxchg*() or arch_cmpxchg*() depending on whether ARCH_ATOMIC is selected. To do this, the generic implementations are prefixed as generic_cmpxchg_*(), and preprocessor definitions map cmpxchg_*()/arch_cmpxchg_*() onto these as appropriate. Once all users are moved over to ARCH_ATOMIC the ifdeffery in the header can be simplified and/or removed entirely. For existing users (none of which select ARCH_ATOMIC), there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210525140232.53872-13-mark.rutland@arm.com
2021-05-25 22:02:11 +08:00
#define generic_cmpxchg64_local(ptr, o, n) \
__generic_cmpxchg64_local((ptr), (o), (n))
#ifndef arch_xchg
#define arch_xchg generic_xchg
#endif
#ifndef arch_cmpxchg_local
#define arch_cmpxchg_local generic_cmpxchg_local
#endif
#ifndef arch_cmpxchg64_local
#define arch_cmpxchg64_local generic_cmpxchg64_local
#endif
#define arch_cmpxchg arch_cmpxchg_local
#define arch_cmpxchg64 arch_cmpxchg64_local
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h to simplify disintegration of asm/system.h. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-29 01:30:03 +08:00
#endif /* __ASM_GENERIC_CMPXCHG_H */
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