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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2017-04-17 10:22:29 -0400
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2017-04-17 10:22:29 -0400
commitfcdc71257923263d042236eaf62bae5e033757b5 (patch)
treee9c1b57da109993c49f0578a3feb61b884a2dbdc /kernel/trace
parentacceb72e90624ec6c3f2fc62e72dab892cd075da (diff)
downloadlinux-fcdc71257923263d042236eaf62bae5e033757b5.tar.bz2
ftrace: Fix indexing of t_hash_start() from t_next()
t_hash_start() does not increment *pos, where as t_next() must. But when t_next() does increment *pos, it must still pass in the original *pos to t_hash_start() otherwise it will skip the first instance: # cd /sys/kernel/debug/tracing # echo schedule:traceoff > set_ftrace_filter # echo do_IRQ:traceoff > set_ftrace_filter # echo call_rcu > set_ftrace_filter # cat set_ftrace_filter call_rcu schedule:traceoff:unlimited do_IRQ:traceoff:unlimited The above called t_hash_start() from t_start() as there was only one function (call_rcu), but if we add another function: # echo xfrm_policy_destroy_rcu >> set_ftrace_filter # cat set_ftrace_filter call_rcu xfrm_policy_destroy_rcu do_IRQ:traceoff:unlimited The "schedule:traceoff" disappears. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/ftrace.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 4b6459a57fbc..b21a3e61ac74 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3205,6 +3205,7 @@ static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
+ loff_t l = *pos; /* t_hash_start() must use original pos */
void *ret;
if (unlikely(ftrace_disabled))
@@ -3216,13 +3217,13 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
if (iter->flags & FTRACE_ITER_PRINTALL) {
/* next must increment pos, and t_hash_start does not */
(*pos)++;
- return t_hash_start(m, pos);
+ return t_hash_start(m, &l);
}
ret = t_func_next(m, pos);
if (!ret)
- return t_hash_start(m, pos);
+ return t_hash_start(m, &l);
return ret;
}