On Tue, 2023-08-01 at 22:52 +0500, Stas Sergeev wrote:
> The locker was waiting for sem_otime on sem0 to became non-zero after
> incrementing sem0 himself. So sem_otime was never 0 at the time of
> checking it, so the check was redundant/wrong.
>
> This patch:
> - moves the increment of sem1 to the lock-tester site
> - lock-setter waits for that sem1 event, for which this patch replaces
> the wait loop on sem_otime with GETVAL loop, adding a small sleep
> - increment of sem0 to 2 moved past that sem1 event. That sem0 event
> is currently not used/waited.
>
> This guarantees that the lock-setter is working only after lock-getter
> is fully initialized.
>
> CC: fstests@xxxxxxxxxxxxxxx
> CC: Murphy Zhou <xzhou@xxxxxxxxxx>
> CC: Jeff Layton <jlayton@xxxxxxxxxx>
> CC: Zorro Lang <zlang@xxxxxxxxxx>
>
> Signed-off-by: Stas Sergeev <stsp2@xxxxxxxxx>
> ---
> src/t_ofd_locks.c | 44 +++++++++++++++++++++++++-------------------
> 1 file changed, 25 insertions(+), 19 deletions(-)
>
> diff --git a/src/t_ofd_locks.c b/src/t_ofd_locks.c
> index 88ef2690..58cb0959 100644
> --- a/src/t_ofd_locks.c
> +++ b/src/t_ofd_locks.c
> @@ -294,32 +294,29 @@ int main(int argc, char **argv)
> semu.array = vals;
> if (semctl(semid, 2, SETALL, semu) == -1)
> err_exit("init sem", errno);
> - /* Inc both new sem to 2 */
> - sop.sem_num = 0;
> - sop.sem_op = 1;
> - sop.sem_flg = 0;
> - ts.tv_sec = 5;
> - ts.tv_nsec = 0;
> - if (semtimedop(semid, &sop, 1, &ts) == -1)
> - err_exit("inc sem0 2", errno);
> - sop.sem_num = 1;
> - sop.sem_op = 1;
> - sop.sem_flg = 0;
> - ts.tv_sec = 5;
> - ts.tv_nsec = 0;
> - if (semtimedop(semid, &sop, 1, &ts) == -1)
> - err_exit("inc sem1 2", errno);
>
> /*
> - * Wait initialization complete. semctl(2) only update
> - * sem_ctime, semop(2) will update sem_otime.
> + * Wait initialization complete.
> */
> ret = -1;
> do {
> + if (ret != -1)
> + usleep(100000);
> memset(&sem_ds, 0, sizeof(sem_ds));
> semu.buf = &sem_ds;
> - ret = semctl(semid, 0, IPC_STAT, semu);
> - } while (!(ret == 0 && sem_ds.sem_otime != 0));
> + ret = semctl(semid, 1, GETVAL, semu);
> + if (ret == -1)
> + err_exit("wait sem1 2", errno);
> + } while (ret != 2);
> +
> + /* Inc sem0 to 2 */
> + sop.sem_num = 0;
> + sop.sem_op = 1;
> + sop.sem_flg = 0;
> + ts.tv_sec = 5;
> + ts.tv_nsec = 0;
> + if (semtimedop(semid, &sop, 1, &ts) == -1)
> + err_exit("inc sem0 2", errno);
>
> /* place the lock */
> if (fcntl(fd, setlk_macro, &flk) < 0)
> @@ -385,6 +382,15 @@ int main(int argc, char **argv)
> err_exit("wait sem1 1", errno);
> } while (ret != 1);
>
> + /* inc sem1 to 2 (initialization completed) */
> + sop.sem_num = 1;
> + sop.sem_op = 1;
> + sop.sem_flg = 0;
> + ts.tv_sec = 5;
> + ts.tv_nsec = 0;
> + if (semtimedop(semid, &sop, 1, &ts) == -1)
> + err_exit("inc sem1 2", errno);
> +
> /* wait sem0 == 0 (setlk and close fd done) */
> sop.sem_num = 0;
> sop.sem_op = 0;
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
