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sched/signal/sig_default.c: The abnormal termination handler was just calling exit() conditionally when, for example, Ctrl-C is sent to a task. The abnormal termination handler must obey the rules of cancellation points: If cancelation is disabled, then the abnormal termintion logic must wait for cancelation to be re-enabled; If cancellation is deffered then the abnormal termination logic may have to wait for the victim task to enter or exit a cancellation point.

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This commit is contained in:
Gregory Nutt 2019-05-17 07:39:04 -06:00
parent ced14b7b58
commit c2136fda6d
1 changed files with 56 additions and 0 deletions
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56
sched/signal/sig_default.c
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@ -53,6 +53,7 @@
#include "group/group.h"
#include "sched/sched.h"
#include "task/task.h"
#include "signal/signal.h"
/****************************************************************************
@ -189,6 +190,61 @@ static void nxsig_abnormal_termination(int signo)
{
FAR struct tcb_s *rtcb = (FAR struct tcb_s *)this_task();
/* Check to see if this task has the non-cancelable bit set in its
* flags. Suppress context changes for a bit so that the flags are stable.
* (the flags should not change in interrupt handling).
*/
sched_lock();
if ((rtcb->flags & TCB_FLAG_NONCANCELABLE) != 0)
{
/* Then we cannot cancel the thread now. Here is how this is
* supposed to work:
*
* "When cancelability is disabled, all cancels are held pending
* in the target thread until the thread changes the cancelability.
* When cancelability is deferred, all cancels are held pending in
* the target thread until the thread changes the cancelability, calls
* a function which is a cancellation point or calls pthread_testcancel(),
* thus creating a cancellation point. When cancelability is asynchronous,
* all cancels are acted upon immediately, interrupting the thread with its
* processing."
*
* REVISIT: Does this rule apply to equally to both SIGKILL and SIGINT?
*/
rtcb->flags |= TCB_FLAG_CANCEL_PENDING;
sched_unlock();
return;
}
#ifdef CONFIG_CANCELLATION_POINTS
/* Check if this task supports deferred cancellation */
if ((rtcb->flags & TCB_FLAG_CANCEL_DEFERRED) != 0)
{
/* Then we cannot cancel the task asynchronously. Mark the cancellation
* as pending.
*/
rtcb->flags |= TCB_FLAG_CANCEL_PENDING;
/* If the task is waiting at a cancellation point, then notify of the
* cancellation thereby waking the task up with an ECANCELED error.
*/
if (rtcb->cpcount > 0)
{
nxnotify_cancellation(rtcb);
}
sched_unlock();
return;
}
#endif
sched_unlock();
/* Careful: In the multi-threaded task, the signal may be handled on a
* child pthread.
*/