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Steven Rostedt (Google) e8d1167385 ring-buffer: Allow splice to read previous partially read pages
commit fa8f4a8973 upstream.

If a page is partially read, and then the splice system call is run
against the ring buffer, it will always fail to read, no matter how much
is in the ring buffer. That's because the code path for a partial read of
the page does will fail if the "full" flag is set.

The splice system call wants full pages, so if the read of the ring buffer
is not yet full, it should return zero, and the splice will block. But if
a previous read was done, where the beginning has been consumed, it should
still be given to the splice caller if the rest of the page has been
written to.

This caused the splice command to never consume data in this scenario, and
let the ring buffer just fill up and lose events.

Link: https://lkml.kernel.org/r/20220927144317.46be6b80@gandalf.local.home

Cc: stable@vger.kernel.org
Fixes: 8789a9e7df ("ring-buffer: read page interface")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-10-26 12:34:30 +02:00
arch powerpc/boot: Explicitly disable usage of SPE instructions 2022-10-26 12:34:25 +02:00
block block: blk_queue_enter() / __bio_queue_enter() must return -EAGAIN for nowait 2022-09-23 14:15:48 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto KEYS: asymmetric: enforce SM2 signature use pkey algo 2022-08-17 14:24:28 +02:00
Documentation fs: record I_DIRTY_TIME even if inode already has I_DIRTY_INODE 2022-10-26 12:34:27 +02:00
drivers fbdev: smscufx: Fix use-after-free in ufx_ops_open() 2022-10-26 12:34:26 +02:00
fs ext4: update 'state->fc_regions_size' after successful memory allocation 2022-10-26 12:34:30 +02:00
include fs: record I_DIRTY_TIME even if inode already has I_DIRTY_INODE 2022-10-26 12:34:27 +02:00
init stack: Declare {randomize_,}kstack_offset to fix Sparse warnings 2022-08-17 14:23:10 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:23:10 +02:00
kernel ring-buffer: Allow splice to read previous partially read pages 2022-10-26 12:34:30 +02:00
lib crypto: lib - remove unneeded selection of XOR_BLOCKS 2022-09-05 10:30:03 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/mmap: undo ->mmap() when arch_validate_flags() fails 2022-10-26 12:34:24 +02:00
net wifi: mac80211: fix MBSSID parsing use-after-free 2022-10-15 07:59:05 +02:00
samples samples/landlock: Format with clang-format 2022-06-09 10:23:23 +02:00
scripts Makefile.extrawarn: Move -Wcast-function-type-strict to W=1 2022-10-12 09:53:26 +02:00
security hardening: Remove Clang's enable flag for -ftrivial-auto-var-init=zero 2022-10-26 12:34:28 +02:00
sound ASoC: wcd934x: fix order of Slimbus unprepare/disable 2022-10-26 12:34:21 +02:00
tools perf parse-events: Identify broken modifiers 2022-10-12 09:53:28 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: SEV: add cache flush to solve SEV cache incoherency issues 2022-09-23 14:15:52 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Input: goodix - add a goodix.h header file 2022-07-12 16:34:51 +02:00
Makefile hardening: Remove Clang's enable flag for -ftrivial-auto-var-init=zero 2022-10-26 12:34:28 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.