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| author | Steven Rostedt (VMware) | 2017-03-30 22:51:43 +0200 |
|---|---|---|
| committer | Steven Rostedt (VMware) | 2017-04-01 00:00:37 +0200 |
| commit | 43ff926a0c3a0cfd6aa313c3232420f009ab43e8 (patch) | |
| tree | d367ba0a6efcf702dde5f9f3592b29c5082b1b84 /init/main.c | |
| parent | ftrace: Return NULL at end of t_start() instead of calling t_hash_start() (diff) | |
| download | kernel-qcow2-linux-43ff926a0c3a0cfd6aa313c3232420f009ab43e8.tar.gz kernel-qcow2-linux-43ff926a0c3a0cfd6aa313c3232420f009ab43e8.tar.xz kernel-qcow2-linux-43ff926a0c3a0cfd6aa313c3232420f009ab43e8.zip | |
ftrace: Update func_pos in t_start() when all functions are enabled
If all functions are enabled, there's a comment displayed in the file to
denote that:
# cd /sys/kernel/debug/tracing
# cat set_ftrace_filter
#### all functions enabled ####
If a function trigger is set, those are displayed as well:
# echo schedule:traceoff >> /debug/tracing/set_ftrace_filter
# cat set_ftrace_filter
#### all functions enabled ####
schedule:traceoff:unlimited
But if you read that file with dd, the output can change:
# dd if=/debug/tracing/set_ftrace_filter bs=1
#### all functions enabled ####
32+0 records in
32+0 records out
32 bytes copied, 7.0237e-05 s, 456 kB/s
This is because the "pos" variable is updated for the comment, but func_pos
is not. "func_pos" is used by the triggers (or hashes) to know how many
functions were printed and it bases its index from the pos - func_pos.
func_pos should be 1 to count for the comment printed. But since it is not,
t_hash_start() thinks that one trigger was already printed.
The cat gets to t_hash_start() via t_next() and not t_start() which updates
both pos and func_pos.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'init/main.c')
0 files changed, 0 insertions, 0 deletions