diff options
Diffstat (limited to 'ports_smp/linux/gnu/src/tx_thread_schedule.c')
| -rw-r--r-- | ports_smp/linux/gnu/src/tx_thread_schedule.c | 41 |
1 files changed, 39 insertions, 2 deletions
diff --git a/ports_smp/linux/gnu/src/tx_thread_schedule.c b/ports_smp/linux/gnu/src/tx_thread_schedule.c index 0c3e8e32..0b6eba25 100644 --- a/ports_smp/linux/gnu/src/tx_thread_schedule.c +++ b/ports_smp/linux/gnu/src/tx_thread_schedule.c @@ -292,6 +292,8 @@ void _tx_linux_mutex_obtain(TX_LINUX_MUTEX *mutex) TX_THREAD *thread_ptr; pthread_t current_thread_id; UINT i; +INT linux_status; +struct timespec ts; /* Pickup the current thread ID. */ current_thread_id = pthread_self(); @@ -343,8 +345,43 @@ UINT i; thread_ptr -> tx_thread_linux_mutex_access = TX_TRUE; } - /* Get the Linux mutex. */ - pthread_mutex_lock(&mutex -> tx_linux_mutex); + /* Get the Linux mutex. The wait is timed and retried rather than left + to pthread_mutex_lock, because a thread can be signalled into the + port's suspend handler while it is parked on this mutex. That handler + does not return until the thread is resumed, so the wake-up the next + release sends is delivered to a thread that never retries and is lost. + Any other thread parked on the mutex then waits on a mutex that is + free, which on this port deadlocks the whole process: the thread that + can resume the suspended one is the scheduler, and the scheduler takes + this mutex on every pass. Retrying on a timeout costs nothing when + the mutex is handed over normally, and turns that lost wake-up into a + delay of at most the retry period. */ + do + { + + /* Set the deadline for this attempt. */ + clock_gettime(CLOCK_REALTIME, &ts); + ts.tv_nsec = ts.tv_nsec + TX_LINUX_MUTEX_RETRY_NSEC; + if (ts.tv_nsec >= 1000000000) + { + + ts.tv_nsec = ts.tv_nsec - 1000000000; + ts.tv_sec++; + } + + linux_status = pthread_mutex_timedlock(&mutex -> tx_linux_mutex, &ts); + + /* Anything but the deadline expiring is a real failure to obtain the + mutex, so stop retrying and record it. */ + if ((linux_status != 0) && (linux_status != ETIMEDOUT)) + { + + /* Increment the system error counter. */ + _tx_linux_system_error++; + break; + } + + } while (linux_status != 0); /* At this point we have the mutex. */ |