git-sem_wait_race

commit 289b098c9e21e2805e3835f9b5780235ab14a290
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Fri Dec 30 00:40:18 2022 +0100

    htl: Fix sem_wait race between read and gsync_wait

    If the value changes between sem_wait's read and the gsync_wait call,
    the kernel will return KERN_INVALID_ARGUMENT, which we have to interpret
    as the value having already changed.

    This fixes applications (e.g. libgo) seeing sem_wait erroneously return
    KERN_INVALID_ARGUMENT.

Gbp-Pq: Topic hurd-i386
Gbp-Pq: Name git-sem_wait_race.diff

diff --git a/sysdeps/htl/sem-timedwait.c b/sysdeps/htl/sem-timedwait.c
index 1b1eec9f59b41c58cb8b1debf91c0e555109c51b..c610804b0843d2bb43ffd4b4aebeb02d1dc819be 100644 (file)
--- a/sysdeps/htl/sem-timedwait.c
+++ b/sysdeps/htl/sem-timedwait.c
@@ -79,7 +79,7 @@ __sem_timedwait_internal (sem_t *restrict sem,
                      ((unsigned int *) &sem->data) + SEM_VALUE_OFFSET,
                      0, flags);
 
-         if (err != 0)
+         if (err != 0 && err != KERN_INVALID_ARGUMENT)
            {
              /* Error, interruption or timeout, abort.  */
              if (err == KERN_TIMEDOUT)
@@ -138,7 +138,7 @@ __sem_timedwait_internal (sem_t *restrict sem,
                err = __lll_wait_intr (&isem->value,
                          SEM_NWAITERS_MASK, flags);
 
-             if (err != 0)
+             if (err != 0 && err != KERN_INVALID_ARGUMENT)
                {
                  /* Error, interruption or timeout, abort.  */
                  if (err == KERN_TIMEDOUT)