Re: [LTP] fanotify22.c: handle multiple asynchronous error events

[linuxtestproject.agent@gmail.com]

Hi Wei,

On 2026-03-31, Wei Gao <wegao@suse.com> wrote:
> fanotify22.c: handle multiple asynchronous error events

> Reported-by: kernel test robot <oliver.sang@intel.com>
> Closes: https://lore.kernel.org/oe-lkp/202602042124.87bd00e3-lkp@intel.com
> Signed-off-by: Wei Gao <wegao@suse.com>

This fixes a known sporadic failure; please add a Fixes: tag referencing
the LTP commit that introduced fanotify22.

> +	for (metadata = (struct fanotify_event_metadata *)buf;
> +			FAN_EVENT_OK(metadata, len);
> +			metadata = FAN_EVENT_NEXT(metadata, len)) {
> +
> +		event_num++;
> +		struct fanotify_event_info_error *info = get_event_info_error(metadata);

Declaration after statement. Move `info` to the top of the for-loop block.
Same issue with `current_pos`, `ret`, and `m` inside the while loop in
do_test(). Kernel coding style requires declarations at the top of each block.

> +		if (info->error != ex->error && (ex->error2 == 0 || info->error != ex->error2)) {
> +			...
> +			continue;
> +		}
> +
> +		if (!first) {
> +			first = metadata;
> +			first_info = info;
> +		}

Logic bug: `first` is set to the first valid event in buffer order, which
may be the error2 (ESHUTDOWN) event with null_fid. check_event() then
validates that event's FID against ex->fid (bad_file_fid) and fails.
Set `first` only when `info->error == ex->error` so the event with the
expected FID is always selected.

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