man/man/io_uring_sqe_set_data: add note on ->user_data validity

It must ALWAYS be set if an application relies on the value for all completions, if not an application may see previous values in there as liburing does not initialize this field. Link: #1265 Signed-off-by: Jens Axboe <[email protected]>
axboe · Oct 12, 2024 · c33234a · c33234a
1 parent dd1aa10
commit c33234a
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diff --git a/man/io_uring_sqe_set_data.3 b/man/io_uring_sqe_set_data.3
@@ -41,6 +41,15 @@ or
 can be called to retrieve the data pointer or value associated with the
 submitted request.
 
+Note that if neither of these functions are called, or the
+.I user_data
+field in the
+.IR sqe
+isn't set manually either, then the field may contain a value from a previous
+use of this sqe. If an application relies on always having a valid
+.I user_data
+value present, it must always assign one to each sqe.
+
 .SH RETURN VALUE
 None
 .SH SEE ALSO