[LTP] [PATCH v8] fanotify22.c: handle multiple asynchronous error events
Jan Kara
jack@suse.cz
Mon May 11 13:30:52 CEST 2026
On Thu 07-05-26 02:53:33, Wei Gao wrote:
> Since the introduction of the asynchronous fserror reporting framework
> (kernel commit 81d2e13a57c9), fanotify22 has encountered sporadic failures
> due to the non-deterministic nature of event delivery and merging:
>
> 1) tcase3 failure: A race condition occurs when the test reads the
> notification fd between two events. Use a poll() and read() loop to wait
> until the expected events are delivered.
>
> 2) tcase4 failure: The kernel may deliver errors as independent events
> instead of a single merged event, as different worker kthreads can
> end up generating each event. As suggested by Jan Kara, this patch
> introduces a consolidate_events() helper. It iterates through the
> event buffer, identifies the primary event matching the expected error,
> accumulates the error_count from all independent events, and updates
> the primary event's count in-place for validation.
>
> Reported-by: kernel test robot <oliver.sang@intel.com>
> Closes: https://lore.kernel.org/oe-lkp/202602042124.87bd00e3-lkp@intel.com
> Suggested-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Wei Gao <wegao@suse.com>
Looks good to me. Feel free to add:
Reviewed-by: Jan Kara <jack@suse.cz>
Honza
> ---
> v7->v8:
> - Fix a logic bug where the test would fail if a secondary error (like ESHUTDOWN) was the first event in the buffer
> - Move variable declarations to the top of blocks to follow the preferred LTP coding style
> .../kernel/syscalls/fanotify/fanotify22.c | 119 +++++++++++++++---
> 1 file changed, 102 insertions(+), 17 deletions(-)
>
> diff --git a/testcases/kernel/syscalls/fanotify/fanotify22.c b/testcases/kernel/syscalls/fanotify/fanotify22.c
> index e8002b160..c124e1904 100644
> --- a/testcases/kernel/syscalls/fanotify/fanotify22.c
> +++ b/testcases/kernel/syscalls/fanotify/fanotify22.c
> @@ -28,6 +28,7 @@
> #include "tst_test.h"
> #include <sys/fanotify.h>
> #include <sys/types.h>
> +#include <poll.h>
>
> #ifdef HAVE_SYS_FANOTIFY_H
> #include "fanotify.h"
> @@ -88,7 +89,6 @@ static void trigger_bad_link_lookup(void)
> ret, BAD_LINK, errno, EUCLEAN);
> }
>
> -
> static void tcase3_trigger(void)
> {
> trigger_bad_link_lookup();
> @@ -104,6 +104,7 @@ static void tcase4_trigger(void)
> static struct test_case {
> char *name;
> int error;
> + int error2;
> unsigned int error_count;
> struct fanotify_fid_t *fid;
> void (*trigger_error)(void);
> @@ -134,37 +135,79 @@ static struct test_case {
> .trigger_error = &tcase4_trigger,
> .error_count = 2,
> .error = EFSCORRUPTED,
> + .error2 = ESHUTDOWN,
> .fid = &bad_file_fid,
> }
> };
>
> +static struct fanotify_event_metadata *consolidate_events(char *buf, size_t len, const struct test_case *ex)
> +{
> + struct fanotify_event_metadata *metadata, *primary = NULL;
> + struct fanotify_event_info_error *info, *primary_info = NULL;
> + unsigned int total_count = 0;
> + int event_num = 0;
> +
> + for (metadata = (struct fanotify_event_metadata *)buf;
> + FAN_EVENT_OK(metadata, len);
> + metadata = FAN_EVENT_NEXT(metadata, len)) {
> +
> + event_num++;
> + info = get_event_info_error(metadata);
> +
> + if (!info) {
> + tst_res(TFAIL, "Event [%d] missing error info", event_num);
> + continue;
> + }
> +
> + if (info->error != ex->error && (ex->error2 == 0 || info->error != ex->error2)) {
> + tst_res(TFAIL, "Event [%d] unexpected errno (%d)",
> + event_num, info->error);
> + continue;
> + }
> +
> + if (!primary && info->error == ex->error) {
> + primary = metadata;
> + primary_info = info;
> + }
> + total_count += info->error_count;
> +
> + tst_res(TINFO, "Event [%d]: errno=%d, error_count=%d",
> + event_num, info->error, info->error_count);
> + }
> +
> + if (primary_info)
> + primary_info->error_count = total_count;
> +
> + return primary;
> +}
> +
> static int check_error_event_info_fid(struct fanotify_event_info_fid *fid,
> const struct test_case *ex)
> {
> struct file_handle *fh = (struct file_handle *) &fid->handle;
>
> if (memcmp(&fid->fsid, &ex->fid->fsid, sizeof(fid->fsid))) {
> - tst_res(TFAIL, "%s: Received bad FSID type (%x...!=%x...)",
> - ex->name, FSID_VAL_MEMBER(fid->fsid, 0),
> + tst_res(TFAIL, "Received bad FSID type (%x...!=%x...)",
> + FSID_VAL_MEMBER(fid->fsid, 0),
> ex->fid->fsid.val[0]);
>
> return 1;
> }
> if (fh->handle_type != ex->fid->handle.handle_type) {
> - tst_res(TFAIL, "%s: Received bad file_handle type (%d!=%d)",
> - ex->name, fh->handle_type, ex->fid->handle.handle_type);
> + tst_res(TFAIL, "Received bad file_handle type (%d!=%d)",
> + fh->handle_type, ex->fid->handle.handle_type);
> return 1;
> }
>
> if (fh->handle_bytes != ex->fid->handle.handle_bytes) {
> - tst_res(TFAIL, "%s: Received bad file_handle len (%d!=%d)",
> - ex->name, fh->handle_bytes, ex->fid->handle.handle_bytes);
> + tst_res(TFAIL, "Received bad file_handle len (%d!=%d)",
> + fh->handle_bytes, ex->fid->handle.handle_bytes);
> return 1;
> }
>
> if (memcmp(fh->f_handle, ex->fid->handle.f_handle, fh->handle_bytes)) {
> - tst_res(TFAIL, "%s: Received wrong handle. "
> - "Expected (%x...) got (%x...) ", ex->name,
> + tst_res(TFAIL, "Received wrong handle. "
> + "Expected (%x...) got (%x...) ",
> *(int *)ex->fid->handle.f_handle, *(int *)fh->f_handle);
> return 1;
> }
> @@ -177,14 +220,15 @@ static int check_error_event_info_error(struct fanotify_event_info_error *info_e
> int fail = 0;
>
> if (info_error->error_count != ex->error_count) {
> - tst_res(TFAIL, "%s: Unexpected error_count (%d!=%d)",
> - ex->name, info_error->error_count, ex->error_count);
> + tst_res(TFAIL, "Unexpected error_count (%d!=%d)",
> + info_error->error_count, ex->error_count);
> fail++;
> }
>
> - if (info_error->error != ex->error) {
> - tst_res(TFAIL, "%s: Unexpected error code value (%d!=%d)",
> - ex->name, info_error->error, ex->error);
> + if (info_error->error != ex->error &&
> + (ex->error2 == 0 || info_error->error != ex->error2)) {
> + tst_res(TFAIL, "Unexpected error code value (%d!=%d)",
> + info_error->error, ex->error);
> fail++;
> }
>
> @@ -248,19 +292,60 @@ static void check_event(char *buf, size_t len, const struct test_case *ex)
> static void do_test(unsigned int i)
> {
> const struct test_case *tcase = &testcases[i];
> - size_t read_len;
> + struct fanotify_event_metadata *m, *primary;
> + struct fanotify_event_info_error *e;
> + char *current_pos;
> + ssize_t ret;
> + size_t read_len = 0;
> + struct pollfd pfd;
> + unsigned int accumulated_count = 0;
> +
> + tst_res(TINFO, "Test case: %s", tcase->name);
>
> SAFE_FANOTIFY_MARK(fd_notify, FAN_MARK_ADD|FAN_MARK_FILESYSTEM,
> FAN_FS_ERROR, AT_FDCWD, MOUNT_PATH);
>
> tcase->trigger_error();
>
> - read_len = SAFE_READ(0, fd_notify, event_buf, BUF_SIZE);
> + pfd.fd = fd_notify;
> + pfd.events = POLLIN;
> +
> + while (accumulated_count < tcase->error_count) {
> + if (poll(&pfd, 1, 5000) <= 0) {
> + tst_res(TFAIL, "Timeout waiting for events");
> + goto out;
> + }
> +
> + if (BUF_SIZE - read_len < FAN_EVENT_METADATA_LEN)
> + tst_brk(TBROK, "Insufficient buffer space for next event");
> +
> + current_pos = event_buf + read_len;
> + ret = SAFE_READ(0, fd_notify, current_pos, BUF_SIZE - read_len);
> +
> + m = (struct fanotify_event_metadata *)current_pos;
> + while (FAN_EVENT_OK(m, ret)) {
> + e = get_event_info_error(m);
> +
> + if (e)
> + accumulated_count += e->error_count;
> +
> + read_len += m->event_len;
> + m = FAN_EVENT_NEXT(m, ret);
> + }
> + }
> +
> + primary = consolidate_events(event_buf, read_len, tcase);
> +
> + if (primary)
> + check_event((char *)primary, primary->event_len, tcase);
> + else
> + tst_res(TFAIL, "No primary error event found");
> +
> +out:
>
> SAFE_FANOTIFY_MARK(fd_notify, FAN_MARK_REMOVE|FAN_MARK_FILESYSTEM,
> FAN_FS_ERROR, AT_FDCWD, MOUNT_PATH);
>
> - check_event(event_buf, read_len, tcase);
> /* Unmount and mount the filesystem to get it out of the error state */
> SAFE_UMOUNT(MOUNT_PATH);
> SAFE_MOUNT(tst_device->dev, MOUNT_PATH, tst_device->fs_type, 0, NULL);
> --
> 2.52.0
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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