linux-kernel - RE: [PATCH] rapidio/tsi721: use tasklet_kill in device remove/release process

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Date:	Mon, 5 Nov 2012 16:11:40 +0000
From:	"Bounine, Alexandre" <Alexandre.Bounine@....com>
To:	Xiaotian Feng <xtfeng@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	Xiaotian Feng <dannyfeng@...cent.com>,
	Matt Porter <mporter@...nel.crashing.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: RE: [PATCH] rapidio/tsi721: use tasklet_kill in device
 remove/release process

On Wed, October 31, 2012 6:53 AM
Xiaotian Feng <xtfeng@...il.com> wrote:
> 
> Some driver uses tasklet_disable in device remove/release process,
> tasklet_disable will inc tasklet->count and return. If the tasklet
> is not handled yet under some softirq pressure, the tasklet will be
> placed on the tasklet_vec, never have a chance to be excuted. This
> might
> lead to a heavy loaded ksoftirqd, wakeup with pending_softirq, but
> tasklet is disabled. tasklet_kill should be used in this case.
> 
> Signed-off-by: Xiaotian Feng <dannyfeng@...cent.com>
> Cc: Matt Porter <mporter@...nel.crashing.org>
> Cc: Alexandre Bounine <alexandre.bounine@....com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> ---
>  drivers/rapidio/devices/tsi721_dma.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/rapidio/devices/tsi721_dma.c
> b/drivers/rapidio/devices/tsi721_dma.c
> index 92e06a5..a098fbc 100644
> --- a/drivers/rapidio/devices/tsi721_dma.c
> +++ b/drivers/rapidio/devices/tsi721_dma.c
> @@ -589,7 +589,7 @@ static void tsi721_free_chan_resources(struct
> dma_chan *dchan)
>  	BUG_ON(!list_empty(&bdma_chan->active_list));
>  	BUG_ON(!list_empty(&bdma_chan->queue));
> 
> -	tasklet_disable(&bdma_chan->tasklet);
> +	tasklet_kill(&bdma_chan->tasklet);
> 
>  	spin_lock_bh(&bdma_chan->lock);
>  	list_splice_init(&bdma_chan->free_list, &list);
> --
> 1.7.9.5

I agree with reported issue.
Switching to tasklet_kill() also requires to disable interrupts first.
I will update that part and post a new patch.

    
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