Re: [PATCH] [RFC] mutex: w/w mutex slowpath debugging

[Steven Rostedt]

On Tue, 2013-04-30 at 20:45 +0200, Daniel Vetter wrote:
> /**
> diff --git a/kernel/mutex.c b/kernel/mutex.c
> index 66807c7..1cc3487 100644
> --- a/kernel/mutex.c
> +++ b/kernel/mutex.c
> @@ -827,6 +827,35 @@ int __sched mutex_trylock(struct mutex *lock)
>  EXPORT_SYMBOL(mutex_trylock);
>  
>  #ifndef CONFIG_DEBUG_LOCK_ALLOC
> +
> +#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
> +static int __sched
> +ww_mutex_deadlock_injection(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
> +{
> +	if (ctx->deadlock_inject_countdown-- == 0) {
> +		tmp = ctx->deadlock_inject_interval;
> +		if (tmp > UINT_MAX/4)
> +			tmp = UINT_MAX;
> +		else
> +			tmp = tmp*2 + tmp + tmp/2;
> +
> +		ctx->deadlock_inject_interval = tmp;
> +		ctx->deadlock_inject_countdown = tmp;
> +
> +		ww_mutex_unlock(lock);
> +
> +		return -EDEADLK;
> +	}
> +
> +	return 0;
> +}
> +#else
> +static int __sched
> +ww_mutex_deadlock_injection(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
> +{
> +	return 0;
> +}

This should be a static inline, and remove the __sched. There's no
reason to make this anything but a nop when disabled.

-- Steve


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