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Date:   Tue, 3 Mar 2020 13:17:41 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Cengiz Can <cengiz@kernel.wtf>
Cc:     kbusch@kernel.org, Chaitanya.Kulkarni@wdc.com, axboe@kernel.dk,
        helgaas@kernel.org, jack@suse.cz, linux-block@vger.kernel.org,
        stable@vger.kernel.org, tristmd@gmail.com
Subject: Re: [PATCH] blktrace: Protect q->blk_trace with RCU
Message-ID: <20200303121741.GA2021063@kroah.com>
References: <20200302220639.GA2393@dhcp-10-100-145-180.wdl.wdc.com>
 <20200303110731.65552-1-cengiz@kernel.wtf>
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On Tue, Mar 03, 2020 at 02:07:32PM +0300, Cengiz Can wrote:
> Added a reassignment into the NULL check block to fix the issue.
> 
> Fixes: c780e86dd48 ("blktrace: Protect q->blk_trace with RCU")
> 
> Signed-off-by: Cengiz Can <cengiz@kernel.wtf>
> ---
>  kernel/trace/blktrace.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> index 4560878f0bac..29ea88f10b87 100644
> --- a/kernel/trace/blktrace.c
> +++ b/kernel/trace/blktrace.c
> @@ -1896,8 +1896,10 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
>  	}
> 
>  	ret = 0;
> -	if (bt == NULL)
> +	if (bt == NULL) {
>  		ret = blk_trace_setup_queue(q, bdev);
> +		bt = q->blk_trace;
> +	}
> 
>  	if (ret == 0) {
>  		if (attr == &dev_attr_act_mask)
> --
> 2.25.1
>

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>