Re: [PATCH v19 19/40] dept: apply timeout consideration to hashed-waitqueue wait

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Missing `sdt_might_sleep_end()` cleanup in the error path of wait macros (e.g., `___wait_var_event`, `___wait_event`, `___swait_event`) bypasses `dept_clean_stage()`, leaking the staged wait event state and corrupting DEPT tracking.
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commit cf04720896ab037609320947c88e8faa57dbddd7
Author: Byungchul Park <byungchul@xxxxxx>

dept: apply timeout consideration to hashed-waitqueue wait

Now that CONFIG_DEPT_AGGRESSIVE_TIMEOUT_WAIT was introduced, apply the
consideration to hashed-waitqueue wait, assuming an input 'ret' in
___wait_var_event() macro is used as a timeout value.

> diff --git a/include/linux/wait_bit.h b/include/linux/wait_bit.h
> index 179a616ad245a..9885ac4e1ded5 100644
> --- a/include/linux/wait_bit.h
> +++ b/include/linux/wait_bit.h
> @@ -258,7 +258,7 @@ extern wait_queue_head_t *__var_waitqueue(void *p);
>  	struct wait_bit_queue_entry __wbq_entry;			\
>  	long __ret = ret; /* explicit shadow */				\
>  									\
> -	sdt_might_sleep_start(NULL);					\
> +	sdt_might_sleep_start_timeout(NULL, __ret);			\

[Severity: High]
Does this error path properly clean up the dept wait state?

Lower in the ___wait_var_event() macro, if a signal is received it jumps to
__out:

		if (___wait_is_interruptible(state) && __int) {		\
			__ret = __int;					\
			goto __out;					\
		}							\
		
		...
		
	sdt_might_sleep_end();						\
__out:	__ret;								\

Because the goto __out branch skips sdt_might_sleep_end(), does it leave a 
dangling stage context in the dept subsystem's tracking graph?  

If the stage context remains populated, could a subsequent wait on the same
task be incorrectly seen as a nested stage, potentially corrupting dept
tracking or leading to false deadlock reports?

(Note: A similar goto __out pattern skipping sdt_might_sleep_end() also
exists in ___wait_event() in include/linux/wait.h and ___swait_event() in
include/linux/swait.h).

>  	init_wait_var_entry(&__wbq_entry, var,				\
>  			    exclusive ? WQ_FLAG_EXCLUSIVE : 0);		\
>  	for (;;) {							\

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Sashiko AI review · https://sashiko.dev/#/patchset/20260706061928.66713-1-byungchul@xxxxxx?part=19