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ringbuf: Fix case where xTaskGetTickCount() overflows but task timeout point doesn't

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This commit is contained in:
Angus Gratton 2016-11-16 17:15:55 +11:00
parent 60f29236f6
commit 8b7d1cdc27
1 changed files with 15 additions and 5 deletions
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20
components/freertos/ringbuf.c
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@ -471,7 +471,8 @@ BaseType_t xRingbufferSend(RingbufHandle_t ringbuf, void *data, size_t dataSize,
ringbuf_t *rb=(ringbuf_t *)ringbuf;
size_t needed_size=dataSize+sizeof(buf_entry_hdr_t);
BaseType_t done=pdFALSE;
portTickType ticks_end=xTaskGetTickCount() + ticks_to_wait;
TickType_t ticks_end = xTaskGetTickCount() + ticks_to_wait;
TickType_t ticks_remaining = ticks_to_wait;
configASSERT(rb);
@ -486,16 +487,25 @@ BaseType_t xRingbufferSend(RingbufHandle_t ringbuf, void *data, size_t dataSize,
if (ringbufferFreeMem(rb) < needed_size) {
//Data does not fit yet. Wait until the free_space_sem is given, then re-evaluate.
BaseType_t r = xSemaphoreTake(rb->free_space_sem, ticks_to_wait);
BaseType_t r = xSemaphoreTake(rb->free_space_sem, ticks_remaining);
if (r == pdFALSE) {
//Timeout.
return pdFALSE;
}
//Adjust ticks_to_wait; we may have waited less than that and in the case the free memory still is not enough,
//Adjust ticks_remaining; we may have waited less than that and in the case the free memory still is not enough,
//we will need to wait some more.
ticks_to_wait = ticks_end - xTaskGetTickCount();
if (ticks_to_wait != portMAX_DELAY) {
ticks_remaining = ticks_end - xTaskGetTickCount();
}
// ticks_remaining will always be less than or equal to the original ticks_to_wait,
// unless the timeout is reached - in which case it unsigned underflows to a much
// higher value.
//
// (Check is written this non-intuitive way to allow for the case where xTaskGetTickCount()
// has overflowed but the ticks_end value has not overflowed.)
}
} while (ringbufferFreeMem(rb) < needed_size && ticks_end >= xTaskGetTickCount());
} while (ringbufferFreeMem(rb) < needed_size && ticks_remaining > 0 && ticks_remaining <= ticks_to_wait);
//Lock the mux in order to make sure no one else is messing with the ringbuffer and do the copy.
portENTER_CRITICAL(&rb->mux);