linux-kernel - Re: [PATCH 3/3] md/raid5: per hash value and exclusive wait_for

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Date:	Thu, 14 May 2015 15:45:11 +1000
From:	NeilBrown <neilb@...e.de>
To:	Yuanhan Liu <yuanhan.liu@...ux.intel.com>
Cc:	linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] md/raid5: per hash value and exclusive
 wait_for_stripe

On Wed, 29 Apr 2015 10:48:55 +0800 Yuanhan Liu <yuanhan.liu@...ux.intel.com>
wrote:

> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 64d5bea..697d77a 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -344,7 +344,8 @@ static void release_inactive_stripe_list(struct r5conf *conf,
>  					 int hash)
>  {
>  	int size;
> -	bool do_wakeup = false;
> +	unsigned long do_wakeup = 0;
> +	int i = 0;
>  	unsigned long flags;
>  
>  	if (hash == NR_STRIPE_HASH_LOCKS) {
> @@ -365,15 +366,19 @@ static void release_inactive_stripe_list(struct r5conf *conf,
>  			    !list_empty(list))
>  				atomic_dec(&conf->empty_inactive_list_nr);
>  			list_splice_tail_init(list, conf->inactive_list + hash);
> -			do_wakeup = true;
> +			do_wakeup |= 1 << (size - 1);
>  			spin_unlock_irqrestore(conf->hash_locks + hash, flags);
>  		}
>  		size--;
>  		hash--;
>  	}
>  
> +	for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++) {
> +		if (do_wakeup & (1 << i))
> +			wake_up(&conf->wait_for_stripe[i]);
> +	}
> +

hi,
 I've been doing some testing and got a lock-up in resize_stripes, waiting
 on wait_for_stripe[].

 Looking at the above code,  I think
      do_wakeup |= 1 << (size - 1);
 should be
      do_wakeup |= 1 << hash;

 do you agree?  Or am I missing something?

Thanks,
NeilBrown


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