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Subject[PATCH] ftrace: Properly unset FTRACE_HASH_FL_MOD
Date
When executing following commands like what document said, but the log
"#### all functions enabled ####" was not shown as expect:
1. Set a 'mod' filter:
$ echo 'write*:mod:ext3' > /sys/kernel/tracing/set_ftrace_filter
2. Invert above filter:
$ echo '!write*:mod:ext3' >> /sys/kernel/tracing/set_ftrace_filter
3. Read the file:
$ cat /sys/kernel/tracing/set_ftrace_filter

By some debugging, I found that flag FTRACE_HASH_FL_MOD was not unset
after inversion like above step 2 and then result of ftrace_hash_empty()
is incorrect.

Cc: stable@vger.kernel.org
Fixes: 8c08f0d5c6fb ("ftrace: Have cached module filters be an active filter")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
---
kernel/trace/ftrace.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 439e2ab6905e..5a1ec7e1af33 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6081,8 +6081,12 @@ int ftrace_regex_release(struct inode *inode, struct file *file)

if (filter_hash) {
orig_hash = &iter->ops->func_hash->filter_hash;
- if (iter->tr && !list_empty(&iter->tr->mod_trace))
- iter->hash->flags |= FTRACE_HASH_FL_MOD;
+ if (iter->tr) {
+ if (list_empty(&iter->tr->mod_trace))
+ iter->hash->flags &= ~FTRACE_HASH_FL_MOD;
+ else
+ iter->hash->flags |= FTRACE_HASH_FL_MOD;
+ }
} else
orig_hash = &iter->ops->func_hash->notrace_hash;

--
2.25.1
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