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HAL_ChibiOS: fixed handling of write mutex

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this fixes an issue with log download on USB and mavlink throughput
caused lock contention. The issue was introduced with the changes for
unbuffered writes recently (does not affect stable releases)
This commit is contained in:
Andrew Tridgell 2020-01-20 08:08:54 +11:00
parent 3e930baf89
commit a8501a91c7
1 changed files with 9 additions and 27 deletions
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36
libraries/AP_HAL_ChibiOS/UARTDriver.cpp
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@ -622,13 +622,7 @@ size_t UARTDriver::write(uint8_t c)
if (lock_write_key != 0) {
return 0;
}
if (unbuffered_writes && _blocking_writes) {
_write_mutex.take_blocking();
} else {
if (!_write_mutex.take_nonblocking()) {
return 0;
}
}
_write_mutex.take_blocking();
if (!_initialised) {
_write_mutex.give();
@ -640,7 +634,10 @@ size_t UARTDriver::write(uint8_t c)
_write_mutex.give();
return 0;
}
// release the semaphore while sleeping
_write_mutex.give();
hal.scheduler->delay(1);
_write_mutex.take_blocking();
}
size_t ret = _writebuf.write(&c, 1);
if (unbuffered_writes) {
@ -657,19 +654,10 @@ size_t UARTDriver::write(const uint8_t *buffer, size_t size)
return 0;
}
if (_blocking_writes && unbuffered_writes) {
_write_mutex.take_blocking();
} else {
if (!_write_mutex.take_nonblocking()) {
return 0;
}
}
if (_blocking_writes && !unbuffered_writes) {
/*
use the per-byte delay loop in write() above for blocking writes
*/
_write_mutex.give();
size_t ret = 0;
while (size--) {
if (write(*buffer++) != 1) break;
@ -678,11 +666,12 @@ size_t UARTDriver::write(const uint8_t *buffer, size_t size)
return ret;
}
WITH_SEMAPHORE(_write_mutex);
size_t ret = _writebuf.write(buffer, size);
if (unbuffered_writes) {
write_pending_bytes();
}
_write_mutex.give();
return ret;
}
@ -713,14 +702,8 @@ size_t UARTDriver::write_locked(const uint8_t *buffer, size_t size, uint32_t key
if (lock_write_key != 0 && key != lock_write_key) {
return 0;
}
if (!_write_mutex.take_nonblocking()) {
return 0;
}
size_t ret = _writebuf.write(buffer, size);
_write_mutex.give();
return ret;
WITH_SEMAPHORE(_write_mutex);
return _writebuf.write(buffer, size);
}
/*
@ -1091,9 +1074,8 @@ void UARTDriver::_timer_tick(void)
// provided by the write() call, but if the write is larger
// than the DMA buffer size then there can be extra bytes to
// send here, and they must be sent with the write lock held
_write_mutex.take_blocking();
WITH_SEMAPHORE(_write_mutex);
write_pending_bytes();
_write_mutex.give();
} else {
write_pending_bytes();
}