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author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2020-11-26 10:54:04 -0300 |
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committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2020-11-27 09:59:13 -0300 |
commit | aa69f19a937b679816ef10e8620ea1141bb1734b (patch) | |
tree | fda886e3c6899912d8ebb5e65ace4710075bbc0f /nptl/pthread_rwlock_common.c | |
parent | 71eeae0325a95f5e5d7ec4a27a6a6c357e0c8ef4 (diff) | |
download | glibc-aa69f19a937b679816ef10e8620ea1141bb1734b.tar.gz glibc-aa69f19a937b679816ef10e8620ea1141bb1734b.tar.xz glibc-aa69f19a937b679816ef10e8620ea1141bb1734b.zip |
nptl: Add EOVERFLOW checks for futex calls
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
Diffstat (limited to 'nptl/pthread_rwlock_common.c')
-rw-r--r-- | nptl/pthread_rwlock_common.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/nptl/pthread_rwlock_common.c b/nptl/pthread_rwlock_common.c index 4c9f582d3d..9ef432c474 100644 --- a/nptl/pthread_rwlock_common.c +++ b/nptl/pthread_rwlock_common.c @@ -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. */ } |