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Mainline Linux tree for various devices, only for fun :)
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Michael Ellerman 7b7622bb95 powerpc/smp: Call smp_ops->setup_cpu() directly on the boot CPU 
In smp_cpus_done() we need to call smp_ops->setup_cpu() for the boot
CPU, which means it has to run *on* the boot CPU.

In the past we ensured it ran on the boot CPU by changing the CPU
affinity mask of current directly. That was removed in commit
6d11b87d55 ("powerpc/smp: Replace open coded task affinity logic"),
and replaced with a work queue call.

Unfortunately using a work queue leads to a lockdep warning, now that
the CPU hotplug lock is a regular semaphore:

  ======================================================
  WARNING: possible circular locking dependency detected
  ...
  kworker/0:1/971 is trying to acquire lock:
   (cpu_hotplug_lock.rw_sem){++++++}, at: [<c000000000100974>] apply_workqueue_attrs+0x34/0xa0

  but task is already holding lock:
   ((&wfc.work)){+.+.+.}, at: [<c0000000000fdb2c>] process_one_work+0x25c/0x800
  ...
       CPU0                    CPU1
       ----                    ----
  lock((&wfc.work));
                               lock(cpu_hotplug_lock.rw_sem);
                               lock((&wfc.work));
  lock(cpu_hotplug_lock.rw_sem);

Although the deadlock can't happen in practice, because
smp_cpus_done() only runs in early boot before CPU hotplug is allowed,
lockdep can't tell that.

Luckily in commit 8fb12156b8 ("init: Pin init task to the boot CPU,
initially") tglx changed the generic code to pin init to the boot CPU
to begin with. The unpinning of init from the boot CPU happens in
sched_init_smp(), which is called after smp_cpus_done().

So smp_cpus_done() is always called on the boot CPU, which means we
don't need the work queue call at all - and the lockdep warning goes
away.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2017-07-28 19:35:45 +10:00
arch powerpc/smp: Call smp_ops->setup_cpu() directly on the boot CPU 2017-07-28 19:35:45 +10:00
block Merge branch 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-06 20:57:13 -07:00
certs scripts/spelling.txt: add "intialise(d)" pattern and fix typo instances 2017-05-08 17:15:13 -07:00
crypto dmaengine updates for 4.13-rc1 2017-07-08 12:36:50 -07:00
Documentation main drm pull for v4.13 2017-07-09 18:48:37 -07:00
drivers main drm pull for v4.13 2017-07-09 18:48:37 -07:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs afs: Add metadata xattrs 2017-07-09 14:40:12 -07:00
include main drm pull for v4.13 2017-07-09 18:48:37 -07:00
init mm: allow slab_nomerge to be set at build time 2017-07-06 16:24:31 -07:00
ipc mqueue: fix a use-after-free in sys_mq_notify() 2017-07-09 14:37:19 -07:00
kernel Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-09 11:16:19 -07:00
lib dmaengine updates for 4.13-rc1 2017-07-08 12:36:50 -07:00
mm Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-07-08 12:17:25 -07:00
net mpls: fix uninitialized in_label var warning in mpls_getroute 2017-07-08 11:26:41 +01:00
samples bpf: fix return in load_bpf_file 2017-07-05 09:05:28 +01:00
scripts Kbuild thin archives updates for v4.13 2017-07-07 15:11:12 -07:00
security Merge branch 'work.memdup_user' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-05 16:05:24 -07:00
sound main drm pull for v4.13 2017-07-09 18:48:37 -07:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-09 10:49:47 -07:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt PPC: 2017-07-06 18:38:31 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS main drm pull for v4.13 2017-07-09 18:48:37 -07:00
Makefile Kbuild thin archives updates for v4.13 2017-07-07 15:11:12 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.