replace sync pause with async pause for nxsig_process

[hujun260]

Summary

In the kernel, we are planning to remove all occurrences of up_cpu_pause as one of the steps to simplify the implementation of critical sections. The goal is to enable spin_lock_irqsave to encapsulate critical sections, thereby facilitating the replacement of critical sections(big lock) with smaller spin_lock_irqsave(small lock)

Impact

up_schedule_sigaction

Testing

Configuring NuttX and compile:
$ ./tools/configure.sh -l qemu-armv8a:nsh_smp
$ make
Running with qemu
$ qemu-system-aarch64 -cpu cortex-a53 -smp 4 -nographic -machine virt,virtualization=on,gic-version=3
-net none -chardev stdio,id=con,mux=on -serial chardev:con -mon chardev=con,mode=readline -kernel ./nuttx

[github-actions]

This PR exceeds the recommended size of 1000 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR might be rejected due to its size.

[xiaoxiang781216]

@hujun260 please rebase your patch to fix the conflict

[github-actions]

This PR exceeds the recommended size of 1000 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR might be rejected due to its size.

[github-actions]

This PR exceeds the recommended size of 1000 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR might be rejected due to its size.

[github-actions]

This PR exceeds the recommended size of 1000 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR might be rejected due to its size.

[github-actions]

This PR exceeds the recommended size of 1000 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR might be rejected due to its size.

[masayuki2009]

@hujun260
I noticed that sighand_test always hangs with qemu-intel64:nsh (non-SMP) after merging this PR.

user_main: signal handler test
sighand_test: Initializing semaphore to 0
sighand_test: Unmasking SIGCHLD
sighand_test: Registering SIGCHLD handler
sighand_test: Starting waiter task
sighand_test: Started waiter_main pid=59
waiter_main: Waiter started
waiter_main: Unmasking signal 32
waiter_main: Registering signal handler
waiter_main: oact.sigaction=0 oact.sa_flags=0 oact.sa_mask=0000000000000000
waiter_main: Waiting on semaphore
sighand_test: Signaling pid=59 with signo=32 sigvalue=42

[hujun260]

@hujun260 I noticed that sighand_test always hangs with qemu-intel64:nsh (non-SMP) after merging this PR.

user_main: signal handler test
sighand_test: Initializing semaphore to 0
sighand_test: Unmasking SIGCHLD
sighand_test: Registering SIGCHLD handler
sighand_test: Starting waiter task
sighand_test: Started waiter_main pid=59
waiter_main: Waiter started
waiter_main: Unmasking signal 32
waiter_main: Registering signal handler
waiter_main: oact.sigaction=0 oact.sa_flags=0 oact.sa_mask=0000000000000000
waiter_main: Waiting on semaphore
sighand_test: Signaling pid=59 with signo=32 sigvalue=42

ok i'll look into this issue

[hujun260]

#13888
fix this issue