From: Vinod Koul <vinod.koul@intel.com>
To: Alexander Kochetkov <al.kochet@gmail.com>
Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
Dan Williams <dan.j.williams@intel.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Krzysztof Kozlowski <krzk@kernel.org>
Subject: Re: [PATCH v2 1/2] dmaengine: pl330: fix descriptor allocation fail
Date: Fri, 20 Oct 2017 11:47:20 +0530 [thread overview]
Message-ID: <20171020061720.GN30097@localhost> (raw)
In-Reply-To: <1507117044-3456-2-git-send-email-al.kochet@gmail.com>
On Wed, Oct 04, 2017 at 02:37:23PM +0300, Alexander Kochetkov wrote:
> If two concurrent threads call pl330_get_desc() when DMAC descriptor
> pool is empty it is possible that allocation for one of threads will fail
> with message:
>
> kernel: dma-pl330 20078000.dma-controller: pl330_get_desc:2469 ALERT!
>
> Here how that can happen. Thread A calls pl330_get_desc() to get
> descriptor. If DMAC descriptor pool is empty pl330_get_desc() allocates
> new descriptor on shared pool using add_desc() and then get newly
> allocated descriptor using pluck_desc(). At the same time thread B calls
> pluck_desc() and take newly allocated descriptor. In that case descriptor
> allocation for thread A will fail.
>
> Using on-stack pool for new descriptor allow avoid the issue described.
> The patch modify pl330_get_desc() to use on-stack pool for allocation
> new descriptors.
Applied, thanks
--
~Vinod
next prev parent reply other threads:[~2017-10-20 6:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-04 11:37 [PATCH v2 0/2] dmaengine: pl330: fix descriptor allocation fail Alexander Kochetkov
2017-10-04 11:37 ` [PATCH v2 1/2] " Alexander Kochetkov
2017-10-16 7:54 ` Alexander Kochetkov
2017-10-17 11:26 ` Marek Szyprowski
2017-10-20 6:17 ` Vinod Koul [this message]
2017-10-04 11:37 ` [PATCH v2 2/2] !!! FOR TESTING ONLY !!! dmaengine: pl330: add verbose message and set NR_DEFAULT_DESC to 1 Alexander Kochetkov
2017-10-17 11:27 ` Marek Szyprowski
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