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authorLinus Torvalds <torvalds@linux-foundation.org>2023-06-21 00:01:08 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2023-06-21 00:01:08 +0200
commit2e30b9734398ad8f29432da63a97728326050536 (patch)
tree6b135cf28353890d3e37188cca45aafc1063b66a /Documentation
parentMerge tag 'for-6.4-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/... (diff)
parenttracing/user_events: Document auto-cleanup and remove dyn_event refs (diff)
downloadlinux-2e30b9734398ad8f29432da63a97728326050536.tar.xz
linux-2e30b9734398ad8f29432da63a97728326050536.zip
Merge tag 'trace-v6.4-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt: - Fix MAINTAINERS file to point to proper mailing list for rtla and rv The mailing list pointed to linux-trace-devel instead of linux-trace-kernel. The former is for the tracing libraries and the latter is for anything in the Linux kernel tree. The wrong mailing list was used because linux-trace-kernel did not exist when rtla and rv were created. - User events: - Fix matching of dynamic events to their user events When user writes to dynamic_events file, a lookup of the registered dynamic events is made, but there were some cases that a match could be incorrectly made. - Add auto cleanup of user events Have the user events automatically get removed when the last reference (file descriptor) is closed. This was asked for to prevent leaks of user events hanging around needing admins to clean them up. - Add persistent logic (but not let user space use it yet) In some cases, having a persistent user event (one that does not get cleaned up automatically) is useful. But there's still debates about how to expose this to user space. The infrastructure is added, but the API is not. - Update the selftests Update the user event selftests to reflect the above changes" * tag 'trace-v6.4-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: tracing/user_events: Document auto-cleanup and remove dyn_event refs selftests/user_events: Adapt dyn_test to non-persist events selftests/user_events: Ensure auto cleanup works as expected tracing/user_events: Add auto cleanup and future persist flag tracing/user_events: Track refcount consistently via put/get tracing/user_events: Store register flags on events tracing/user_events: Remove user_ns walk for groups selftests/user_events: Add perf self-test for empty arguments events selftests/user_events: Clear the events after perf self-test selftests/user_events: Add ftrace self-test for empty arguments events tracing/user_events: Fix the incorrect trace record for empty arguments events tracing: Modify print_fields() for fields output order tracing/user_events: Handle matching arguments that is null from dyn_events tracing/user_events: Prevent same name but different args event tracing/rv/rtla: Update MAINTAINERS file to point to proper mailing list
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/trace/user_events.rst7
1 files changed, 3 insertions, 4 deletions
diff --git a/Documentation/trace/user_events.rst b/Documentation/trace/user_events.rst
index f79987e16cf4..e7b07313550a 100644
--- a/Documentation/trace/user_events.rst
+++ b/Documentation/trace/user_events.rst
@@ -14,10 +14,6 @@ Programs can view status of the events via
/sys/kernel/tracing/user_events_status and can both register and write
data out via /sys/kernel/tracing/user_events_data.
-Programs can also use /sys/kernel/tracing/dynamic_events to register and
-delete user based events via the u: prefix. The format of the command to
-dynamic_events is the same as the ioctl with the u: prefix applied.
-
Typically programs will register a set of events that they wish to expose to
tools that can read trace_events (such as ftrace and perf). The registration
process tells the kernel which address and bit to reflect if any tool has
@@ -144,6 +140,9 @@ its name. Delete will only succeed if there are no references left to the
event (in both user and kernel space). User programs should use a separate file
to request deletes than the one used for registration due to this.
+**NOTE:** By default events will auto-delete when there are no references left
+to the event. Flags in the future may change this logic.
+
Unregistering
-------------
If after registering an event it is no longer wanted to be updated then it can