From: Christoph Hellwig <hch@lst.de>
To: Ricardo Ribalda <ribalda@chromium.org>
Cc: Max Staudt <mstaudt@chromium.org>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Ming Lei <tom.leiming@gmail.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Yunke Cao <yunkec@chromium.org>, Christoph Hellwig <hch@lst.de>,
linux-usb@vger.kernel.org, Alan Stern <stern@rowland.harvard.edu>,
linux-kernel@vger.kernel.org, linux-media@vger.kernel.org
Subject: Re: [PATCH v3 2/2] media: uvcvideo: Do not alloc dev->status
Date: Thu, 15 Dec 2022 13:48:37 +0100 [thread overview]
Message-ID: <20221215124837.GA19113@lst.de> (raw)
In-Reply-To: <20221214-uvc-status-alloc-v3-2-9a67616cc549@chromium.org>
On Thu, Dec 15, 2022 at 11:57:19AM +0100, Ricardo Ribalda wrote:
> + /*
> + * Ensure that status is aligned, making it safe to use with
> + * non-coherent DMA.
> + */
> + struct uvc_status status __aligned(ARCH_KMALLOC_MINALIGN);
This should be ARCH_DMA_MINALIGN, not ARCH_KMALLOC_MINALIGN.
Note that without an __aligned tag on the next member as well, those
next members might get cache corrupted.
>
> struct input_dev *input;
.. and without also aligning the next member you'll might still
corrupt everything adter the DMAed member.
That's the reason why I generall advocate against playing these
__aligned games as they can easily go wrong if someone reorders
the structure.
next prev parent reply other threads:[~2022-12-15 12:48 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-15 10:57 [PATCH v3 0/2] media: uvcvideo: Code cleanup for dev->status Ricardo Ribalda
2022-12-15 10:57 ` [PATCH v3 1/2] media: uvcvideo: Remove void casting for the status endpoint Ricardo Ribalda
2022-12-15 11:07 ` Ricardo Ribalda
2022-12-15 10:57 ` [PATCH v3 2/2] media: uvcvideo: Do not alloc dev->status Ricardo Ribalda
2022-12-15 12:48 ` Christoph Hellwig [this message]
2022-12-20 22:59 ` Ricardo Ribalda
2022-12-15 15:34 ` [PATCH v3 0/2] media: uvcvideo: Code cleanup for dev->status Alan Stern
2022-12-16 8:55 ` Ricardo Ribalda
2022-12-16 15:45 ` Alan Stern
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