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authorBeau Belgrave <beaub@linux.microsoft.com>2023-06-14 18:33:36 +0200
committerSteven Rostedt (Google) <rostedt@goodmis.org>2023-06-14 19:43:27 +0200
commit0113d4615dbf053ae9a7a1e0acbc6652713af01f (patch)
treecac6ffcf8c67bdf74a394b4a16d5df6b1c674b98 /Documentation
parentselftests/user_events: Adapt dyn_test to non-persist events (diff)
downloadlinux-0113d4615dbf053ae9a7a1e0acbc6652713af01f.tar.xz
linux-0113d4615dbf053ae9a7a1e0acbc6652713af01f.zip
tracing/user_events: Document auto-cleanup and remove dyn_event refs
Now user_events auto-cleanup upon the last reference by default. This makes it not possible to use the dynamics event file via tracefs. Document that auto-cleanup is enabled by default and remove the refernce to /sys/kernel/tracing/dynamic_events file to make this clear. Link: https://lkml.kernel.org/r/20230614163336.5797-7-beaub@linux.microsoft.com Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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