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Filename Latest commit message Latest commit date
Xiao Yang 0026e356e5 tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation
commit 0bbe7f719985efd9adb3454679ecef0984cb6800 upstream.

Traced event can trigger 'snapshot' operation(i.e. calls snapshot_trigger()
or snapshot_count_trigger()) when register_snapshot_trigger() has completed
registration but doesn't allocate buffer for 'snapshot' event trigger.  In
the rare case, 'snapshot' operation always detects the lack of allocated
buffer so make register_snapshot_trigger() allocate buffer first.

trigger-snapshot.tc in kselftest reproduces the issue on slow vm:
-----------------------------------------------------------
cat trace
...
ftracetest-3028  [002] ....   236.784290: sched_process_fork: comm=ftracetest pid=3028 child_comm=ftracetest child_pid=3036
     <...>-2875  [003] ....   240.460335: tracing_snapshot_instance_cond: *** SNAPSHOT NOT ALLOCATED ***
     <...>-2875  [003] ....   240.460338: tracing_snapshot_instance_cond: *** stopping trace here!   ***
-----------------------------------------------------------

Link: http://lkml.kernel.org/r/20200414015145.66236-1-yangx.jy@cn.fujitsu.com

Cc: stable@vger.kernel.org
Fixes: 93e31ffbf4 ("tracing: Add 'snapshot' event trigger command")
Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-21 09:04:59 +02:00
arch arm64: vdso: don't free unallocated pages 2020-04-21 09:04:58 +02:00
block block, bfq: fix use-after-free in bfq_idle_slice_timer_body 2020-04-17 10:50:05 +02:00
certs
crypto crypto: rng - Fix a refcounting bug in crypto_rng_reset() 2020-04-17 10:50:16 +02:00
Documentation ALSA: hda/realtek - Remove now-unnecessary XPS 13 headphone noise fixups 2020-04-17 10:50:08 +02:00
drivers usb: dwc3: gadget: Don't clear flags before transfer ended 2020-04-21 09:04:55 +02:00
fs ext4: fix incorrect inodes per group in error message 2020-04-21 09:04:53 +02:00
include net: ipv6: do not consider routes via gateways for anycast address check 2020-04-21 09:04:45 +02:00
init
ipc
kernel tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation 2020-04-21 09:04:59 +02:00
lib xarray: Fix early termination of xas_for_each_marked 2020-04-17 10:50:18 +02:00
LICENSES
mm mm, memcg: do not high throttle allocators based on wraparound 2020-04-17 10:50:17 +02:00
net net/bpfilter: remove superfluous testing message 2020-04-21 09:04:53 +02:00
samples
scripts
security keys: Fix proc_keys_next to increase position index 2020-04-21 09:04:58 +02:00
sound ALSA: usb-audio: Check mapping at creating connector controls, too 2020-04-21 09:04:57 +02:00
tools perf report: Fix no branch type statistics report issue 2020-04-21 09:04:52 +02:00
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Makefile Linux 5.4.33 2020-04-17 10:50:26 +02:00
README

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.