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ftrace: Fix t_hash_start()

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When the output of set_ftrace_filter is larger than PAGE_SIZE,
t_hash_start() will be called the 2nd time, and then we start
from the head of a hlist, which is wrong and causes some entries
to be outputed twice.

The worse is, if the hlist is large enough, reading set_ftrace_filter
won't stop but in a dead loop.

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: <4A41876E.2060407@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Li Zefan 2009-06-24 09:54:54 +08:00 committed by Ingo Molnar
parent 694ce0a544
commit d82d62444f
1 changed files with 11 additions and 1 deletions
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12
kernel/trace/ftrace.c
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@ -1417,10 +1417,20 @@ static void *t_hash_start(struct seq_file *m, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
void *p = NULL;
loff_t l;
if (!(iter->flags & FTRACE_ITER_HASH))
*pos = 0;
iter->flags |= FTRACE_ITER_HASH;
return t_hash_next(m, p, pos);
iter->hidx = 0;
for (l = 0; l <= *pos; ) {
p = t_hash_next(m, p, &l);
if (!p)
break;
}
return p;
}
static int t_hash_show(struct seq_file *m, void *v)