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nptl: Add EOVERFLOW checks for futex calls

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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
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6
nptl/pthread_mutex_timedlock.c
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@@ -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,