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Prevent recursive processing of us_ticker in FSL 

When a ticker is scheduled to run so fast that it is pending again
before the previous event has been processed then this next event
is processed (recursively) by calling into us_ticker_irq_handle().
This can lead to a stack overflow.

This patch prevents this recursion by replacing the call to
us_ticker_irq_handler() with a call to set the interrupt to pending
again.  This allows the next timer event to be processed without
making the stack deeper.
Russ Butler 2016-04-03 16:55:15 -05:00 committed by Marcus Shawcroft
parent 1d0aee9065
commit 85be4b7898
1 changed files with 5 additions and 2 deletions
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7
libraries/mbed/targets/hal/TARGET_Freescale/TARGET_KPSDK_MCUS/us_ticker.c
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@ -68,8 +68,11 @@ void us_ticker_clear_interrupt(void) {
void us_ticker_set_interrupt(timestamp_t timestamp) { void us_ticker_set_interrupt(timestamp_t timestamp) {
int delta = (int)(timestamp - us_ticker_read()); int delta = (int)(timestamp - us_ticker_read());
if (delta <= 0) { if (delta <= 0) {
// This event was in the past: // This event was in the past.
us_ticker_irq_handler(); // Set the interrupt as pending, but don't process it here.
// This prevents a recurive loop under heavy load
// which can lead to a stack overflow.
NVIC_SetPendingIRQ(PIT3_IRQn);
return; return;
} }