cpu0 cpu1:
user_main
signest_test
sched_unlock
nxsched_merge_pending
nxsched_add_readytorun
up_cpu_pause
arm_sigdeliver
enter_critical_section
Reason:
In the SMP, cpu0 is already in the critical section and waiting for cpu1 to enter the suspended state.
However, when cpu1 executes arm_sigdeliver, it is in the irq-disabled state but not in the critical section.
At this point, cpu1 is unable to respond to interrupts and
is continuously attempting to enter the critical section, resulting in a deadlock.
Resolve:
adjust the logic, do not entering the critical section when interrupt-disabled.
test:
We can use qemu for testing.
compiling
make distclean -j20; ./tools/configure.sh -l qemu-armv8a:nsh_smp ;make -j20
running
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
Signed-off-by: hujun5 <hujun5@xiaomi.com>
ed78646798