This commit backs out most of commit b4747286b1. That change was added because sem_wait() would sometimes cause cancellation points inappropriated. But with these recent changes, nxsem_wait() is used instead and it is not a cancellation point.
In the OS, all calls to sem_wait() changed to nxsem_wait(). nxsem_wait() does not return errors via errno so each place where nxsem_wait() is now called must not examine the errno variable.
In all OS functions (not libraries), change sem_wait() to nxsem_wait(). This will prevent the OS from creating bogus cancellation points and from modifying the per-task errno variable.
sched/semaphore: Add the function nxsem_wait(). This is a new internal OS interface. It is functionally equivalent to sem_wait() except that (1) it is not a cancellation point, and (2) it does not set the per-thread errno value on return.
sched/semaphore: Add nxsem_post() which is identical to sem_post() except that it never modifies the errno variable. Changed all references to sem_post in the OS to nxsem_post().
sched/semaphore: Add nxsem_destroy() which is identical to sem_destroy() except that it never modifies the errno variable. Changed all references to sem_destroy() in the OS to nxsem_destroy().
libc/semaphore and sched/semaphore: Add nxsem_getprotocol() and nxsem_setprotocola which are identical to sem_getprotocol() and set_setprotocol() except that they never modifies the errno variable. Changed all references to sem_setprotocol in the OS to nxsem_setprotocol(). sem_getprotocol() was not used in the OS
libc/semaphore: Add nxsem_getvalue() which is identical to sem_getvalue() except that it never modifies the errno variable. Changed all references to sem_getvalue in the OS to nxsem_getvalue().
sched/semaphore: Rename all internal private functions from sem_xyz to nxsem_xyz. The sem_ prefix is (will be) reserved only for the application semaphore interfaces.
libc/semaphore: Add nxsem_init() which is identical to sem_init() except that it never modifies the errno variable. Changed all references to sem_init in the OS to nxsem_init().
sched/semaphore: Rename sem_tickwait() to nxsem_tickwait() so that it is clear this is an internal OS function.
sched/semaphoate: Rename sem_reset() to nxsem_reset() so that it is clear this is an internal OS function.
net/socket/recvfrom.c: Check fromlen integrity before using it.
net/socket/net_sockets.c: Always check for valid psock before using.
net/tcp/tcp_send_unbuffered.c: Avoid using psock beforing checking its integrity.
sched/timer/timer_create.c: Fix watchdog resource leak if cannot allocate a new timer.
Add clock_resynchronize for better synchronization of CLOCK_REALTIME and CLOCK_MONOTONIC to match RTC after resume from low-power state.
Add up_rtc_getdatetime_with_subseconds under CONFIG_ARCH_HAVE_RTC_SUBSECONDS to allow initializing (and resynchronizing) system clock with subseconds accuracy RTC.
Entropy pool gathers environmental noise from device drivers, user-space, etc., and returns good random numbers, suitable for cryptographic use. Based on entropy pool design from *BSDs and uses BLAKE2Xs algorithm for CSPRNG output.
Patch also adds /dev/urandom support for using entropy pool RNG and new 'getrandom' system call for getting randomness without file-descriptor usage (thus avoiding file-descriptor exhaustion attacks). The 'getrandom' interface is similar as 'getentropy' and 'getrandom' available on OpenBSD and Linux respectively.
This was a consequence of the recent robust mutex changes. If robust mutexes are selected, then each mutex that a thread takes is retained in a list in threads TCB. If the thread exits and that list is not empty, then we know that the thread exitted while holding mutexes. And, in that case, each will be marked as inconsistent and the any waiter for the thread is awakened.
For the case of pthread_mutex_trywait(), the mutex was not being added to the list! while not usually a fatal error, this was caught by an assertion when pthread_mutex_unlock() was called: It tried to remove the mutex from the TCB list and it was not there when, of course, it shoule be.
The fix was to add pthread_mutex_trytake() which does sem_trywait() and if successful, does correctly add the mutext to the TCB list. This should eliminated the assertion.
Gregory Nutt