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| author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2017-03-30 16:51:43 -0400 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2017-03-31 18:00:37 -0400 |
| commit | 43ff926a0c3a0cfd6aa313c3232420f009ab43e8 (patch) | |
| tree | d367ba0a6efcf702dde5f9f3592b29c5082b1b84 /kernel | |
| parent | 2d71d98900b8a4bd58c3ca92e404d5e3701de874 (diff) | |
| download | linux-43ff926a0c3a0cfd6aa313c3232420f009ab43e8.tar.gz linux-43ff926a0c3a0cfd6aa313c3232420f009ab43e8.tar.bz2 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 'kernel')
| -rw-r--r-- | kernel/trace/ftrace.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 421530831ddd..d4b18ce9ba88 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3230,6 +3230,7 @@ static void *t_start(struct seq_file *m, loff_t *pos) */ if ((iter->flags & (FTRACE_ITER_FILTER | FTRACE_ITER_NOTRACE)) && ftrace_hash_empty(iter->hash)) { + iter->func_pos = 1; /* Account for the message */ if (*pos > 0) return t_hash_start(m, pos); iter->flags |= FTRACE_ITER_PRINTALL; |