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Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning is enabled

From Jason Low <jason.low2@hpe.com>
Newsgroups linux.kernel
Subject Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning is enabled
Date 2016-08-11 04:40 +0200
Message-ID <s4O4x-5g3-5@gated-at.bofh.it> (permalink)
References <s4GJI-j6-57@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Wed, 2016-08-10 at 11:44 -0700, Jason Low wrote:
> @@ -917,11 +976,12 @@ EXPORT_SYMBOL(mutex_trylock);
>  int __sched
>  __ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
>  {
> -	int ret;
> +	int ret = 1;
>  
>  	might_sleep();
>  
> -	ret = __mutex_fastpath_lock_retval(&lock->base.count);
> +	if (!need_yield_to_waiter(lock))
> +		ret = __mutex_fastpath_lock_retval(&lock->base.count);
>  
>  	if (likely(!ret)) {
>  		ww_mutex_set_context_fastpath(lock, ctx);
> @@ -935,11 +995,12 @@ EXPORT_SYMBOL(__ww_mutex_lock);
>  int __sched
>  __ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
>  {
> -	int ret;
> +	int ret = 1;
>  
>  	might_sleep();
>  
> -	ret = __mutex_fastpath_lock_retval(&lock->base.count);
> +	if (!need_yield_to_waiter(lock))

And we would need to pass &lock->base instead of lock since lock is
struct ww_mutex * here.

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Thread

[PATCH v2] locking/mutex: Prevent lock starvation when spinning is  enabled Jason Low <jason.low2@hpe.com> - 2016-08-10 20:50 +0200
  Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning  is enabled Jason Low <jason.low2@hpe.com> - 2016-08-11 00:10 +0200
  Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning  is enabled Jason Low <jason.low2@hpe.com> - 2016-08-11 04:40 +0200
  Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning  is enabled Jason Low <jason.low2@hpe.com> - 2016-08-16 21:50 +0200
  Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning  is enabled Wanpeng Li <kernellwp@gmail.com> - 2016-08-17 03:50 +0200
    Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning  is enabled Jason Low <jason.low2@hpe.com> - 2016-08-17 20:40 +0200
      Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning  is enabled Wanpeng Li <kernellwp@gmail.com> - 2016-08-18 02:40 +0200
  Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning  is enabled Peter Zijlstra <peterz@infradead.org> - 2016-08-18 16:30 +0200
    Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning  is enabled Peter Zijlstra <peterz@infradead.org> - 2016-08-19 02:50 +0200
      Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning  is enabled Peter Zijlstra <peterz@infradead.org> - 2016-08-19 02:50 +0200
  Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning  is enabled Peter Zijlstra <peterz@infradead.org> - 2016-08-18 16:50 +0200

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