tracing: Move mutex to protect against resetting of seq data

The iter->seq can be reset outside the protection of the mutex. So can
reading of user data. Move the mutex up to the beginning of the function.

Fixes: d7350c3f45694 ("tracing/core: make the read callbacks reentrants")
Cc: # 2.6.30+
Reported-by: Al Viro <>
Signed-off-by: Steven Rostedt <>
1 file changed