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sched/semaphore: check unmasked pending signals before blocking. #18672

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Merged
xiaoxiang781216 merged 1 commit into from
Apr 7, 2026
+22 −0
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sched/semaphore: check unmasked pending signals before blocking. #18672

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22 changes: 22 additions & 0 deletions sched/semaphore/sem_wait.c
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,9 @@
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include <nuttx/mm/kmap.h>
#ifdef CONFIG_ENABLE_ALL_SIGNALS
#include <nuttx/signal.h>
#endif

#include "sched/sched.h"
#include "semaphore/semaphore.h"
Expand Down Expand Up @@ -71,6 +74,9 @@

int nxsem_wait_slow(FAR sem_t *sem)
{
#ifdef CONFIG_ENABLE_ALL_SIGNALS
sigset_t pendingset;
#endif
FAR struct tcb_s *rtcb = this_task();
irqstate_t flags;
int ret = OK;
Expand All @@ -87,6 +93,22 @@ int nxsem_wait_slow(FAR sem_t *sem)

/* Make sure we were supplied with a valid semaphore. */

#ifdef CONFIG_ENABLE_ALL_SIGNALS
/* A signal can arrive before sem_wait transitions the task to
* TSTATE_WAIT_SEM. In that window, the wait cannot yet be aborted by
* sem_wait_irq(). If sem_wait then blocks without re-checking unmasked
* pending signals, it can sleep indefinitely and miss the interrupt.
*/

pendingset = nxsig_pendingset(rtcb);
nxsig_nandset(&pendingset, &pendingset, &rtcb->sigprocmask);
if (!sigisemptyset(&pendingset))
{
leave_critical_section(flags);
return -EINTR;
}
#endif

/* Check if the lock is available */

if (mutex)
Expand Down
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