Aksal/nuttx
3
1
Fork 1
mirror of https://github.com/apache/nuttx.git synced 2026-08-01 20:28:58 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 2

sched/semaphore: check unmasked pending signals before blocking.

Browse source 
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.

Check for unmasked pending signals before touching the
semaphore count and return -EINTR if one is already pending.

Signed-off-by: Shunchao Hu <ankohuu@gmail.com>
This commit is contained in:
Shunchao Hu 2026-04-03 22:42:57 +08:00 • committed by Xiang Xiao
parent b843d9192e
commit 5f6e1e2d7e
1 changed files with 22 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

22
sched/semaphore/sem_wait.c
View file

@ -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"
@ -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;
@ -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)