From: Beau Belgrave <beaub@linux.microsoft.com>
To: rostedt@goodmis.org, mhiramat@kernel.org
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
ast@kernel.org, dcook@linux.microsoft.com
Subject: [PATCH v3 6/6] tracing/user_events: Document auto-cleanup and remove dyn_event refs
Date: Wed, 14 Jun 2023 09:33:36 -0700 [thread overview]
Message-ID: <20230614163336.5797-7-beaub@linux.microsoft.com> (raw)
In-Reply-To: <20230614163336.5797-1-beaub@linux.microsoft.com>
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.
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
---
Documentation/trace/user_events.rst | 7 +++----
1 file 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
--
2.25.1
prev parent reply other threads:[~2023-06-14 16:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-14 16:33 [PATCH v3 0/6] tracing/user_events: Add auto cleanup and a flag to persist events Beau Belgrave
2023-06-14 16:33 ` [PATCH v3 1/6] tracing/user_events: Store register flags on events Beau Belgrave
2023-06-14 16:33 ` [PATCH v3 2/6] tracing/user_events: Track refcount consistently via put/get Beau Belgrave
2023-06-14 16:33 ` [PATCH v3 3/6] tracing/user_events: Add auto cleanup and future persist flag Beau Belgrave
2023-06-14 16:33 ` [PATCH v3 4/6] selftests/user_events: Ensure auto cleanup works as expected Beau Belgrave
2023-06-14 16:33 ` [PATCH v3 5/6] selftests/user_events: Adapt dyn_test to non-persist events Beau Belgrave
2023-06-14 16:33 ` Beau Belgrave [this message]
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