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authorLi Zefan <lizf@cn.fujitsu.com>2009-06-24 09:54:19 +0800
committerIngo Molnar <mingo@elte.hu>2009-06-24 11:02:53 +0200
commit694ce0a544fba37a60025a6803ee6265be8a2a22 (patch)
treea6debd92de0dcf7b42dc129402ca793c540091ae /kernel
parent85951842a1020669f0a9eb0f0d1853b41341f097 (diff)
ftrace: Don't manipulate @pos in t_start()
It's rather confusing that in t_start(), in some cases @pos is incremented, and in some cases it's decremented and then incremented. This patch rewrites t_start() in a much more general way. Thus we fix a bug that if ftrace_filtered == 1, functions have tracer hooks won't be printed, because the branch is always unreachable: static void *t_start(...) { ... if (!p) return t_hash_start(m, pos); return p; } Before: # echo 'sys_open' > /mnt/tracing/set_ftrace_filter # echo 'sys_write:traceon:4' >> /mnt/tracing/set_ftrace_filter sys_open After: # echo 'sys_open' > /mnt/tracing/set_ftrace_filter # echo 'sys_write:traceon:4' >> /mnt/tracing/set_ftrace_filter sys_open sys_write:traceon:count=4 Reviewed-by: Liming Wang <liming.wang@windriver.com> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <4A41874B.4090507@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/ftrace.c19
1 files changed, 8 insertions, 11 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index cde74b9973b..dc810208edd 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1467,8 +1467,6 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
iter->pg = iter->pg->next;
iter->idx = 0;
goto retry;
- } else {
- iter->idx = -1;
}
} else {
rec = &iter->pg->records[iter->idx++];
@@ -1497,6 +1495,7 @@ static void *t_start(struct seq_file *m, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
void *p = NULL;
+ loff_t l;
mutex_lock(&ftrace_lock);
/*
@@ -1508,23 +1507,21 @@ static void *t_start(struct seq_file *m, loff_t *pos)
if (*pos > 0)
return t_hash_start(m, pos);
iter->flags |= FTRACE_ITER_PRINTALL;
- (*pos)++;
return iter;
}
if (iter->flags & FTRACE_ITER_HASH)
return t_hash_start(m, pos);
- if (*pos > 0) {
- if (iter->idx < 0)
- return p;
- (*pos)--;
- iter->idx--;
+ iter->pg = ftrace_pages_start;
+ iter->idx = 0;
+ for (l = 0; l <= *pos; ) {
+ p = t_next(m, p, &l);
+ if (!p)
+ break;
}
- p = t_next(m, p, pos);
-
- if (!p)
+ if (!p && iter->flags & FTRACE_ITER_FILTER)
return t_hash_start(m, pos);
return p;