On Wed, 28 Jun 2023 15:18:11 +0300
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@xxxxxxxxx> wrote:
> The enable_trace_eprobe() function enables all event probes, attached
> to given trace probe. If an error occurs in enabling one of the event
> probes, all others should be roll backed. There is a bug in that roll
> back logic - instead of all event probes, only the failed one is
> disabled.
>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events")
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
> ---
> kernel/trace/trace_eprobe.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
> index 67e854979d53..ba9a28bc773f 100644
> --- a/kernel/trace/trace_eprobe.c
> +++ b/kernel/trace/trace_eprobe.c
> @@ -702,8 +702,12 @@ static int enable_trace_eprobe(struct trace_event_call *call,
>
> if (ret) {
> /* Failed to enable one of them. Roll back all */
> - if (enabled)
> - disable_eprobe(ep, file->tr);
> + if (enabled) {
If one was enabled and the second one failed, that should only happen
if there's a bug in the kernel (unless the failure was due to a memory
problem).
I wonder if we should add:
int cnt = 0;
> + list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
/*
* It's a bug if one failed for something other than memory
* not being available but another eprobe succeeded.
*/
WARN_ON_ONCE(cnt++ && ret != -ENOMEM);
-- Steve
> + ep = container_of(pos, struct trace_eprobe, tp);
> + disable_eprobe(ep, file->tr);
> + }
> + }
> if (file)
> trace_probe_remove_file(tp, file);
> else
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