Hi,
I have a question about sem_wait. Current implementation in NuttX can
return failure and set errno to ECANCELED in case if the semaphore wait is
done while code is inside the cancelation point. However I do not see
ECANCELED in the POSIX description of sem_wait. Can anyone bring some more
ligh
Hi Petro,
According with OpenGroup there is not ECANCELED as possible return:
https://pubs.opengroup.org/onlinepubs/7908799/xsh/sem_wait.html
Maybe it should be replaced with EINTR case it was cancelled because
was interrupted by a signal.
BR,
Alan
On 5/26/22, Petro Karashchenko wrote:
> Hi,
Hi,
This question arises during the review of one PRs. Indeed, it seems that
ECANCELED should never be returned to the app
because leave_cancellation_point() should terminate the task; however there
are quite a few places in code that check ECANCELED returned by semaphore.
Those are:
- mm_takesema
nxsem_wait() is not a cancellation point. There are no cancellation
points within the OS, onl nsy at the application interface. So sem_wait()
is a cancellation point; It nxsem_wait() will not. nxsem_wait() will
not cause the thread calling nxsem_wait() but will return ECANCELED.
In these ca
Hi,
Ok. That makes sense. But there is a strane code in sem_wait:
if (enter_cancellation_point())
{
#ifdef CONFIG_CANCELLATION_POINTS
/* If there is a pending cancellation, then do not perform
* the wait. Exit now with ECANCELED.
*/
errcode = ECANCELED;
got
