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Date:   Mon, 17 Feb 2020 14:06:50 -0800 (PST)
Message-Id: <20200217.140650.510071134243739795.davem@davemloft.net>
To:     horatiu.vultur@microchip.com
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        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: mscc: fix in frame extraction
From:   David Miller <davem@davemloft.net>
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From: Horatiu Vultur <horatiu.vultur@microchip.com>
Date: Mon, 17 Feb 2020 09:31:33 +0100

> Each extracted frame on Ocelot has an IFH. The frame and IFH are extracted
> by reading chuncks of 4 bytes from a register.
> 
> In case the IFH and frames were read corretly it would try to read the next
> frame. In case there are no more frames in the queue, it checks if there
> were any previous errors and in that case clear the queue. But this check
> will always succeed also when there are no errors. Because when extracting
> the IFH the error is checked against 4(number of bytes read) and then the
> error is set only if the extraction of the frame failed. So in a happy case
> where there are no errors the err variable is still 4. So it could be
> a case where after the check that there are no more frames in the queue, a
> frame will arrive in the queue but because the error is not reseted, it
> would try to flush the queue. So the frame will be lost.
> 
> The fix consist in resetting the error after reading the IFH.
> 
> Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>

Applied and queued up for -stable.