linux-kernel - Re: [PATCH] scsi: wd719x Replace GFP_KERNEL with GFP_ATOMIC in wd719x_chip

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Date:   Mon, 14 Jan 2019 07:29:43 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     wangbo <wdjjwb@....com>
Cc:     linux-kernel@...r.kernel.org, martin.petersen@...cle.com,
        linux-scsi@...r.kernel.org, wang.bo116@....com.cn,
        Ondrej Zary <linux@...nbow-software.org>
Subject: Re: [PATCH] scsi: wd719x Replace GFP_KERNEL with GFP_ATOMIC in
 wd719x_chip_init

On Mon, Jan 14, 2019 at 11:24:49PM +0800, wangbo wrote:
> wd719x_host_reset get spinlock first then call wd719x_chip_init,
> so replace GFP_KERNEL with GFP_ATOMIC in wd719x_chip_init.

Please move the allocation outside the lock instead.  GFP_ATOMIC
DMA allocations are generally a bad idea and should be avoided where
we can.

More importantly we should never actually trigger the allocation
under the lock as far as fw_virt will always be set already
in that case.

So I think you can safely move the request firmware + allocation
+ memcpy from wd719x_chip_init to wd719x_board_found, but I'd rather
have Ondrej review that plan.