Re: [PATCH] ftrace: Properly unset FTRACE_HASH_FL_MOD

[Steven Rostedt]

On Mon, 26 Sep 2022 15:20:08 +0000
Zheng Yejian <zhengyejian1@xxxxxxxxxx> wrote:

> 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@xxxxxxxxxxxxxxx
> Fixes: 8c08f0d5c6fb ("ftrace: Have cached module filters be an active filter")
> Signed-off-by: Zheng Yejian <zhengyejian1@xxxxxxxxxx>

Thanks, this definitely looks like a bug.

I'll be reviewing these patches later this week.

-- Steve