AuroraMiddleware/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2024-11-21 20:40:05 +00:00
Code Issues Packages Projects Releases Wiki Activity

nptl: Add EOVERFLOW checks for futex calls

Browse Source 
Some futex-internal calls require additional check for EOVERFLOW (as
indicated by [1] [2] [3]).  For both mutex and rwlock code, EOVERFLOW is
handle as ETIMEDOUT; since it indicate to the caller that the blocking
operation could not be issued.

For mutex it avoids a possible issue where PTHREAD_MUTEX_ROBUST_* might
assume EOVERFLOW indicate futex has succeed, and for PTHREAD_MUTEX_PP_*
it avoid a potential busy infinite loop.  For rwlock and semaphores, it
also avoids potential busy infinite loops.

Checked on x86_64-linux-gnu and i686-linux-gnu, although EOVERFLOW
won't be possible with current usage (since all timeouts on 32-bit
architectures with 32-bit time_t support will be in the range of
32-bit time_t).

[1] https://sourceware.org/pipermail/libc-alpha/2020-November/120079.html
[2] https://sourceware.org/pipermail/libc-alpha/2020-November/120080.html
[3] https://sourceware.org/pipermail/libc-alpha/2020-November/120127.html
This commit is contained in:
Adhemerval Zanella 2020-11-26 10:54:04 -03:00
parent 71eeae0325
commit aa69f19a93
4 changed files with 13 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
nptl/pthread_cond_wait.c
View File

@ -506,7 +506,7 @@ __pthread_cond_wait_common (pthread_cond_t *cond, pthread_mutex_t *mutex,
__pthread_cleanup_pop (&buffer, 0);
if (__glibc_unlikely (err == ETIMEDOUT))
if (__glibc_unlikely (err == ETIMEDOUT || err == EOVERFLOW))
{
__condvar_dec_grefs (cond, g, private);
/* If we timed out, we effectively cancel waiting. Note that
@ -515,7 +515,7 @@ __pthread_cond_wait_common (pthread_cond_t *cond, pthread_mutex_t *mutex,
__condvar_quiesce_and_switch_g1 and us trying to acquire
the lock during cancellation is not possible. */
__condvar_cancel_waiting (cond, seq, g, private);
result = ETIMEDOUT;
result = err;
goto done;
}
else

6
nptl/pthread_mutex_timedlock.c
View File

@ -270,7 +270,7 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
oldval, clockid, abstime,
PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
/* The futex call timed out. */
if (err == ETIMEDOUT)
if (err == ETIMEDOUT || err == EOVERFLOW)
return err;
/* Reload current lock value. */
oldval = mutex->__data.__lock;
@ -550,8 +550,8 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
int e = __futex_abstimed_wait64 (
(unsigned int *) &mutex->__data.__lock, ceilval | 2,
clockid, abstime, PTHREAD_MUTEX_PSHARED (mutex));
if (e == ETIMEDOUT)
return ETIMEDOUT;
if (e == ETIMEDOUT || e == EOVERFLOW)
return e;
}
}
while (atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,

14
nptl/pthread_rwlock_common.c
View File

@ -334,7 +334,7 @@ __pthread_rwlock_rdlock_full64 (pthread_rwlock_t *rwlock, clockid_t clockid,
private);
/* We ignore EAGAIN and EINTR. On time-outs, we can just
return because we don't need to clean up anything. */
if (err == ETIMEDOUT)
if (err == ETIMEDOUT || err == EOVERFLOW)
return err;
}
/* It makes sense to not break out of the outer loop here
@ -460,7 +460,7 @@ __pthread_rwlock_rdlock_full64 (pthread_rwlock_t *rwlock, clockid_t clockid,
int err = __futex_abstimed_wait64 (&rwlock->__data.__wrphase_futex,
1 | PTHREAD_RWLOCK_FUTEX_USED,
clockid, abstime, private);
if (err == ETIMEDOUT)
if (err == ETIMEDOUT || err == EOVERFLOW)
{
/* If we timed out, we need to unregister. If no read phase
has been installed while we waited, we can just decrement
@ -479,7 +479,7 @@ __pthread_rwlock_rdlock_full64 (pthread_rwlock_t *rwlock, clockid_t clockid,
if (atomic_compare_exchange_weak_relaxed
(&rwlock->__data.__readers, &r,
r - (1 << PTHREAD_RWLOCK_READER_SHIFT)))
return ETIMEDOUT;
return err;
/* TODO Back-off. */
}
/* Use the acquire MO fence to mirror the steps taken in the
@ -730,7 +730,7 @@ __pthread_rwlock_wrlock_full64 (pthread_rwlock_t *rwlock, clockid_t clockid,
int err = __futex_abstimed_wait64 (&rwlock->__data.__writers_futex,
1 | PTHREAD_RWLOCK_FUTEX_USED,
clockid, abstime, private);
if (err == ETIMEDOUT)
if (err == ETIMEDOUT || err == EOVERFLOW)
{
if (prefer_writer)
{
@ -758,7 +758,7 @@ __pthread_rwlock_wrlock_full64 (pthread_rwlock_t *rwlock, clockid_t clockid,
}
/* We cleaned up and cannot have stolen another waiting writer's
futex wake-up, so just return. */
return ETIMEDOUT;
return err;
}
/* If we got interrupted (EINTR) or the futex word does not have the
expected value (EAGAIN), retry after reloading __readers. */
@ -829,7 +829,7 @@ __pthread_rwlock_wrlock_full64 (pthread_rwlock_t *rwlock, clockid_t clockid,
int err = __futex_abstimed_wait64 (&rwlock->__data.__wrphase_futex,
PTHREAD_RWLOCK_FUTEX_USED,
clockid, abstime, private);
if (err == ETIMEDOUT)
if (err == ETIMEDOUT || err == EOVERFLOW)
{
if (rwlock->__data.__flags != PTHREAD_RWLOCK_PREFER_READER_NP)
{
@ -861,7 +861,7 @@ __pthread_rwlock_wrlock_full64 (pthread_rwlock_t *rwlock, clockid_t clockid,
if ((wf & PTHREAD_RWLOCK_FUTEX_USED) != 0)
futex_wake (&rwlock->__data.__writers_futex,
1, private);
return ETIMEDOUT;
return err;
}
/* TODO Back-off. */
}

2
nptl/sem_waitcommon.c
View File

@ -191,7 +191,7 @@ __new_sem_wait_slow64 (struct new_sem *sem, clockid_t clockid,
documentation. Before Linux 2.6.22, EINTR was also returned on
spurious wake-ups; we only support more recent Linux versions,
so do not need to consider this here.) */
if (err == ETIMEDOUT || err == EINTR)
if (err == ETIMEDOUT || err == EINTR || err == EOVERFLOW)
{
__set_errno (err);
err = -1;