Posted on November 11, 2015 at 18:58Hi,
This code generated by STM32Cube with FreeRTOS looks like it has a bug.
To reproduce, create a small pool. Allocate a single item that is not free'd then, allocate and deallocate sucessive items. The pool will stop allocating, even though there are free slots.
The code at fault is,
index = pool_id->currentIndex + i;
if (index >= pool_id->pool_sz) {
index = 0;
}
currentIndex is never reset, and so for a queue size of say 8, if currentIndex = 7, then for all i (1,2,3..) in the loop, currentindex + i will be greater than pool_sz. and index will be set to 0, so only markers[0] gets checked continiously. If index 0 is not free, then the pool will not allocate, and will break in this condition
The above section should be something like
index = (pool_id->currentIndex + i) % pool_id->pool_sz;
FULL FUNCTION:
void *osPoolAlloc (osPoolId pool_id)
{
int dummy = 0;
void *p = NULL;
uint32_t i;
uint32_t index;
if (inHandlerMode()) {
dummy = portSET_INTERRUPT_MASK_FROM_ISR();
}
else {
vPortEnterCritical();
}
for (i = 0; i < pool_id->pool_sz; i++) {
index = pool_id->currentIndex + i;
if (index >= pool_id->pool_sz) {
index = 0;
}
if (pool_id->markers[index] == 0) {
pool_id->markers[index] = 1;
p = (void *)((uint32_t)(pool_id->pool) + (index * pool_id->item_sz));
pool_id->currentIndex = index;
break;
}
}
if (inHandlerMode()) {
portCLEAR_INTERRUPT_MASK_FROM_ISR(dummy);
}
else {
vPortExitCritical();
}
return p;
}
