linux.git/kernel/trace/trace_events_trigger.c, branch v6.1.168

tracing: Add NULL pointer check to trigger_data_free()

2026-03-25T10:03:02+00:00

[ Upstream commit 457965c13f0837a289c9164b842d0860133f6274 ]

If trigger_data_alloc() fails and returns NULL, event_hist_trigger_parse()
jumps to the out_free error path. While kfree() safely handles a NULL
pointer, trigger_data_free() does not. This causes a NULL pointer
dereference in trigger_data_free() when evaluating
data->cmd_ops->set_filter.

Fix the problem by adding a NULL pointer check to trigger_data_free().

The problem was found by an experimental code review agent based on
gemini-3.1-pro while reviewing backports into v6.18.y.

Cc: Miaoqian Lin 
Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Steven Rostedt (Google) 
Link: https://patch.msgid.link/20260305193339.2810953-1-linux@roeck-us.net
Fixes: 0550069cc25f ("tracing: Properly process error handling in event_hist_trigger_parse()")
Assisted-by: Gemini:gemini-3.1-pro
Signed-off-by: Guenter Roeck 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Sasha Levin

tracing: Fix error handling in event_trigger_parse()

2025-06-27T10:07:10+00:00

[ Upstream commit c5dd28e7fb4f63475b50df4f58311df92939d011 ]

According to trigger_data_alloc() doc, trigger_data_free() should be
used to free an event_trigger_data object. This fixes a mismatch introduced
when kzalloc was replaced with trigger_data_alloc without updating
the corresponding deallocation calls.

Cc: Masami Hiramatsu 
Cc: Mark Rutland 
Cc: Andrew Morton 
Cc: Mathieu Desnoyers 
Cc: Tom Zanussi 
Link: https://lore.kernel.org/20250507145455.944453325@goodmis.org
Link: https://lore.kernel.org/20250318112737.4174-1-linmq006@gmail.com
Fixes: e1f187d09e11 ("tracing: Have existing event_command.parse() implementations use helpers")
Signed-off-by: Miaoqian Lin 
[ SDR: Changed event_trigger_alloc/free() to trigger_data_alloc/free() ]
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Sasha Levin

tracing: Rename event_trigger_alloc() to trigger_data_alloc()

2025-06-27T10:07:10+00:00

[ Upstream commit f2947c4b7d0f235621c5daf78aecfbd6e22c05e5 ]

The function event_trigger_alloc() creates an event_trigger_data
descriptor and states that it needs to be freed via event_trigger_free().
This is incorrect, it needs to be freed by trigger_data_free() as
event_trigger_free() adds ref counting.

Rename event_trigger_alloc() to trigger_data_alloc() and state that it
needs to be freed via trigger_data_free(). This naming convention
was introducing bugs.

Cc: Masami Hiramatsu 
Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Cc: Andrew Morton 
Cc: Tom Zanussi 
Link: https://lore.kernel.org/20250507145455.776436410@goodmis.org
Fixes: 86599dbe2c527 ("tracing: Add helper functions to simplify event_command.parse() callback handling")
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Sasha Levin

ftrace: Fix preemption accounting for stacktrace trigger command

2025-05-22T12:10:05+00:00

commit e333332657f615ac2b55aa35565c4a882018bbe9 upstream.

When using the stacktrace trigger command to trace syscalls, the
preemption count was consistently reported as 1 when the system call
event itself had 0 (".").

For example:

root@ubuntu22-vm:/sys/kernel/tracing/events/syscalls/sys_enter_read
$ echo stacktrace > trigger
$ echo 1 > enable

    sshd-416     [002] .....   232.864910: sys_read(fd: a, buf: 556b1f3221d0, count: 8000)
    sshd-416     [002] ...1.   232.864913: 
 => ftrace_syscall_enter
 => syscall_trace_enter
 => do_syscall_64
 => entry_SYSCALL_64_after_hwframe

The root cause is that the trace framework disables preemption in __DO_TRACE before
invoking the trigger callback.

Use the tracing_gen_ctx_dec() that will accommodate for the increase of
the preemption count in __DO_TRACE when calling the callback. The result
is the accurate reporting of:

    sshd-410     [004] .....   210.117660: sys_read(fd: 4, buf: 559b725ba130, count: 40000)
    sshd-410     [004] .....   210.117662: 
 => ftrace_syscall_enter
 => syscall_trace_enter
 => do_syscall_64
 => entry_SYSCALL_64_after_hwframe

Cc: stable@vger.kernel.org
Fixes: ce33c845b030c ("tracing: Dump stacktrace trigger to the corresponding instance")
Link: https://lore.kernel.org/20250512094246.1167956-1-dolinux.peng@gmail.com
Signed-off-by: pengdonglin 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing/trigger: Fix to return error if failed to alloc snapshot

2024-02-23T08:12:32+00:00

commit 0958b33ef5a04ed91f61cef4760ac412080c4e08 upstream.

Fix register_snapshot_trigger() to return error code if it failed to
allocate a snapshot instead of 0 (success). Unless that, it will register
snapshot trigger without an error.

Link: https://lore.kernel.org/linux-trace-kernel/170622977792.270660.2789298642759362200.stgit@devnote2

Fixes: 0bbe7f719985 ("tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation")
Cc: stable@vger.kernel.org
Cc: Vincent Donnefort 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix to check event_mutex is held while accessing trigger list

2022-09-07T02:26:00+00:00

Since the check_user_trigger() is called outside of RCU
read lock, this list_for_each_entry_rcu() caused a suspicious
RCU usage warning.

 # echo hist:keys=pid > events/sched/sched_stat_runtime/trigger
 # cat events/sched/sched_stat_runtime/trigger
[   43.167032]
[   43.167418] =============================
[   43.167992] WARNING: suspicious RCU usage
[   43.168567] 5.19.0-rc5-00029-g19ebe4651abf #59 Not tainted
[   43.169283] -----------------------------
[   43.169863] kernel/trace/trace_events_trigger.c:145 RCU-list traversed in non-reader section!!
...

However, this file->triggers list is safe when it is accessed
under event_mutex is held.
To fix this warning, adds a lockdep_is_held check to the
list_for_each_entry_rcu().

Link: https://lkml.kernel.org/r/166226474977.223837.1992182913048377113.stgit@devnote2

Cc: stable@vger.kernel.org
Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events")
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Steven Rostedt (Google)

tracing: Fix comments for event_trigger_separate_filter()

2022-05-27T02:03:52+00:00

The parameter name in comments of event_trigger_separate_filter() is
inconsistent with actual parameter name, fix it.

Link: https://lkml.kernel.org/r/20220526072957.165655-1-sunliming@kylinos.cn

Signed-off-by: sunliming 
Signed-off-by: Steven Rostedt (Google)

tracing: Replace usage of found with dedicated list iterator variable

2022-04-27T21:19:31+00:00

To move the list iterator variable into the list_for_each_entry_*()
macro in the future it should be avoided to use the list iterator
variable after the loop body.

To *never* use the list iterator variable after the loop it was
concluded to use a separate iterator variable instead of a
found boolean [1].

This removes the need to use a found variable and simply checking if
the variable was set, can determine if the break/goto was hit.

Link: https://lkml.kernel.org/r/20220427170734.819891-4-jakobkoschel@gmail.com

Cc: Ingo Molnar 
Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel 
Signed-off-by: Steven Rostedt (Google)

tracing: Have existing event_command.parse() implementations use helpers

2022-04-26T21:58:50+00:00

Simplify the existing event_command.parse() implementations by having
them make use of the helper functions previously introduced.

Link: https://lkml.kernel.org/r/b353e3427a81f9d3adafd98fd7d73e78a8209f43.1644010576.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi 
Signed-off-by: Steven Rostedt (Google)

tracing: Remove redundant trigger_ops params

2022-04-26T21:58:50+00:00

Since event_trigger_data contains the .ops trigger_ops field, there's
no reason to pass the trigger_ops separately. Remove it as a param
from functions whenever event_trigger_data is passed.

Link: https://lkml.kernel.org/r/9856c9bc81bde57077f5b8d6f8faa47156c6354a.1644010575.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi 
Signed-off-by: Steven Rostedt (Google)