rqspinlock: Annotate rqspinlock lock acquiring functions with __must_check

[kernel-patches-daemon-bpf]

Pull request for series with
subject: rqspinlock: Annotate rqspinlock lock acquiring functions with __must_check
version: 2
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=1026504

[kernel-patches-daemon-bpf]

Upstream branch: 792f258
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1026504
version: 2

[kernel-patches-review-bot]

commit 4ba76c7812846cfb67d2eeece9bd8e2868a5aa12
Author: Amery Hung <ameryhung@gmail.com>

rqspinlock: Annotate rqspinlock lock acquiring functions with __must_check

Locking a resilient queued spinlock can fail when deadlock or timeout
happen. This patch adds __must_check annotations to ensure callers
handle returned errors. The macro-to-function conversions enable these
annotations.

> diff --git a/include/asm-generic/rqspinlock.h b/include/asm-generic/rqspinlock.h
> index 6d4244d64..855c09435 100644
> --- a/include/asm-generic/rqspinlock.h
> +++ b/include/asm-generic/rqspinlock.h

[ ... ]

> @@ -171,7 +171,7 @@ static __always_inline void release_held_lock_entry(void)
>   * * -EDEADLK	- Lock acquisition failed because of AA/ABBA deadlock.
>   * * -ETIMEDOUT - Lock acquisition failed because of timeout.
>   */
> -static __always_inline int res_spin_lock(rqspinlock_t *lock)
> +static __always_inline __must_check int res_spin_lock(rqspinlock_t *lock)
>  {
>  	int val = 0;
>
> @@ -223,27 +223,36 @@ static __always_inline void res_spin_unlock(rqspinlock_t *lock)
>  #define raw_res_spin_lock_init(lock) ({ *(lock) = (rqspinlock_t){0}; })
>  #endif
>
> -#define raw_res_spin_lock(lock)                    \
> -	({                                         \
> -		int __ret;                         \
> -		preempt_disable();                 \
> -		__ret = res_spin_lock(lock);	   \
> -		if (__ret)                         \
> -			preempt_enable();          \
> -		__ret;                             \
> -	})
> +static __always_inline __must_check int raw_res_spin_lock(rqspinlock_t *lock)
> +{
> +	int ret;
> +
> +	preempt_disable();
> +	ret = res_spin_lock(lock);
> +	if (ret)
> +		preempt_enable();
> +
> +	return ret;
> +}
>
>  #define raw_res_spin_unlock(lock) ({ res_spin_unlock(lock); preempt_enable(); })
>
> -#define raw_res_spin_lock_irqsave(lock, flags)    \
> -	({                                        \
> -		int __ret;                        \
> -		local_irq_save(flags);            \
> -		__ret = raw_res_spin_lock(lock);  \
> -		if (__ret)                        \
> -			local_irq_restore(flags); \
> -		__ret;                            \
> -	})
> +static __always_inline __must_check int
> +__raw_res_spin_lock_irqsave(rqspinlock_t *lock, unsigned long *flags)
> +{
> +	unsigned long __flags;
> +	int ret;
> +
> +	local_irq_save(__flags);
> +	ret = raw_res_spin_lock(lock);
> +	if (ret)
> +		local_irq_restore(__flags);
> +
> +	*flags = __flags;
> +	return ret;
> +}
> +
> +#define raw_res_spin_lock_irqsave(lock, flags) __raw_res_spin_lock_irqsave(lock, &flags)

The __must_check annotations will cause compiler warnings in
kernel/locking/locktorture.c where torture_raw_res_spin_write_lock()
and torture_raw_res_spin_write_lock_irq() ignore lock acquisition
failures.

When raw_res_spin_lock() returns an error (deadlock or timeout), the
torture test functions still return 0 to indicate success. The torture
framework then calls the unlock functions, but the lock was never
acquired. In res_spin_unlock(), this causes an out-of-bounds array
access when computing locks[cnt - 1] with cnt=0, potentially corrupting
per-CPU memory.

Should the torture test handle lock acquisition failures, or use
different lock types that cannot fail?

---

AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

In-Reply-To-Subject: rqspinlock: Annotate rqspinlock lock acquiring functions with __must_check
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/19583558278

[kernel-patches-daemon-bpf]

Forwarding comment 3564643279 via email
In-Reply-To: 20251121205724.2934650-1-ameryhung@gmail.com
Patch: https://patchwork.kernel.org/project/netdevbpf/patch/20251121205724.2934650-1-ameryhung@gmail.com/

[kernel-patches-daemon-bpf]

Upstream branch: 878ee3c
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1026504
version: 2

[kernel-patches-daemon-bpf]

Upstream branch: ae24fc8
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1026504
version: 2

[kernel-patches-daemon-bpf]

Upstream branch: 4dd3a48
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1026504
version: 2

[kernel-patches-daemon-bpf]

Upstream branch: 8f7cf30
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1026504
version: 2

[kernel-patches-daemon-bpf]

Upstream branch: c427320
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1026504
version: 2