Re: [PATCH v2 08/12] KVM: selftests: Add KVM syscall wrapper for pthread_create()

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Using `__KVM_SYSCALL_DEFINE` to wrap `pthread_create` results in misleading error messages on failure, as it logs `errno` instead of the returned error code.
--

--- Patch [8]: [PATCH v2 08/12] KVM: selftests: Add KVM syscall wrapper for pthread_create() ---
commit dca849bcf7bfa248030e1f22bebefccde9e01db3
Author: Sean Christopherson <[email protected]>

KVM: selftests: Add KVM syscall wrapper for pthread_create()

This commit adds a wrapper for the pthread_create() syscall to the KVM
selftests. It replaces manual error checking across the selftests with the
new wrapper which automatically asserts success.

[ ... ]
> diff --git a/tools/testing/selftests/kvm/include/kvm_syscalls.h b/tools/testing/selftests/kvm/include/kvm_syscalls.h
> index 01dca99009c2f..e75be83787798 100644
> --- a/tools/testing/selftests/kvm/include/kvm_syscalls.h
> +++ b/tools/testing/selftests/kvm/include/kvm_syscalls.h
[ ... ]
> @@ -97,6 +98,10 @@ __KVM_SYSCALL_DEFINE(madvise, 3, void *, addr, size_t, length, int, advice);
>  __KVM_SYSCALL_DEFINE(sched_getaffinity, 3, pid_t, pid, size_t, cpusetsize, cpu_set_t *, mask);
>  __KVM_SYSCALL_DEFINE(sched_setaffinity, 3, pid_t, pid, size_t, cpusetsize, cpu_set_t *, mask);
>  
> +typedef void *(*pthread_fn_t)(void *);
> +__KVM_SYSCALL_DEFINE(pthread_create, 4, pthread_t *, thread,
> +		     const pthread_attr_t *, attr, pthread_fn_t, fn, void *, arg);
> +

[Severity: Low]
Does this wrapper format the error message correctly on failure?

The __KVM_SYSCALL_DEFINE macro uses __KVM_SYSCALL_ERROR to format the error
string, which reads errno and uses strerror(errno).

However, POSIX specifies that pthread_create returns the error code directly
and does not set errno.

If pthread_create fails, wouldn't this print a stale errno, or print "Success"
if errno happened to be zero, rather than reporting the actual returned error
code?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=8