From: Vinod Koul <vkoul@kernel.org>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org,
Dan Williams <dan.j.williams@intel.com>,
Dave Jiang <dave.jiang@intel.com>, Kit Chow <kchow@gigaio.com>
Subject: Re: [PATCH 2/5] dmaengine: Call module_put() after device_free_chan_resources()
Date: Tue, 24 Dec 2019 10:07:13 +0530 [thread overview]
Message-ID: <20191224043713.GH2536@vkoul-mobl> (raw)
In-Reply-To: <20191216190120.21374-3-logang@deltatee.com>
On 16-12-19, 12:01, Logan Gunthorpe wrote:
> The module reference is taken to ensure the callbacks still exist
> when they are called. If the channel holds the last reference to the
> module, the module can disappear before device_free_chan_resources() is
> called and would cause a call into free'd memory.
>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> ---
> drivers/dma/dmaengine.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 4b604086b1b3..776fdf535a3a 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -250,7 +250,6 @@ static void dma_chan_put(struct dma_chan *chan)
> return;
>
> chan->client_count--;
> - module_put(dma_chan_to_owner(chan));
>
> /* This channel is not in use anymore, free it */
> if (!chan->client_count && chan->device->device_free_chan_resources) {
> @@ -259,6 +258,8 @@ static void dma_chan_put(struct dma_chan *chan)
> chan->device->device_free_chan_resources(chan);
> }
>
> + module_put(dma_chan_to_owner(chan));
> +
> /* If the channel is used via a DMA request router, free the mapping */
> if (chan->router && chan->router->route_free) {
> chan->router->route_free(chan->router->dev, chan->route_data);
I think this should be moved here after route_free() and will take care
of route cleanup as well
Thanks
--
~Vinod
next prev parent reply other threads:[~2019-12-24 4:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-16 19:01 [PATCH 0/5] Support hot-unbind in IOAT Logan Gunthorpe
2019-12-16 19:01 ` [PATCH 1/5] dmaengine: Store module owner in dma_device struct Logan Gunthorpe
2019-12-16 19:01 ` [PATCH 2/5] dmaengine: Call module_put() after device_free_chan_resources() Logan Gunthorpe
2019-12-24 4:37 ` Vinod Koul [this message]
2019-12-16 19:01 ` [PATCH 3/5] dmaengine: Move dma_channel_rebalance() infrastructure up in code Logan Gunthorpe
2019-12-16 19:01 ` [PATCH 4/5] dmaengine: Add reference counting to dma_device struct Logan Gunthorpe
2019-12-16 19:01 ` [PATCH 5/5] dmaengine: ioat: Support in-use unbind Logan Gunthorpe
2019-12-17 16:33 ` Dave Jiang
2019-12-24 4:50 ` [PATCH 0/5] Support hot-unbind in IOAT Vinod Koul
2019-12-25 2:25 ` Logan Gunthorpe
-- strict thread matches above, loose matches on Subject: below --
2019-10-22 21:46 [PATCH 0/5] PLX Switch DMA Engine Driver Logan Gunthorpe
2019-10-22 21:46 ` [PATCH 2/5] dmaengine: Call module_put() after device_free_chan_resources() Logan Gunthorpe
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