From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-181.mta0.migadu.com (out-181.mta0.migadu.com [91.218.175.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8725D221FB6 for ; Tue, 5 Aug 2025 19:32:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.181 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754422374; cv=none; b=MPixQoD4VgpQDypUx4/njgCpck6himcnbgCXcuuISrUqKlriRKAsPPQ5D/Cq0vjkseDBrJpMWkYMAE6uCgRl3tN5oBPsdN9l55woq+HQJiVaK1QBEqIZbzooqbL864eiRfCFV9URQgUjN0J7ro+acx2E3FrII8/BNwLLGIK8tuY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754422374; c=relaxed/simple; bh=f5YTjW9VECJW0G23VM5eCIi2OhPiZ2wKeAH97xCkiHU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kURavsy185SUyoklZyCoOAPob6b82jDxdRygAnN4DigyjcE2H8La/RWjvl+kcCS3gEDn0n3myNjZIv8UNKBfKGlXhFPR1o5THmIFHxsHj2Q+iKRVl3Sapps+X2bI3r5EzOd2dFUTTruVjZFuQTVLIiLV9Pa/re0sfzQWze10Z5g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=rVO1Gy+/; arc=none smtp.client-ip=91.218.175.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="rVO1Gy+/" Message-ID: <08bd431d-c887-4f69-9c1e-4b40a301ecf7@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1754422369; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vYUMZ7E+6vJC5FpLL2HyF+nE/45hsY2ZWy2Xc7WZ050=; b=rVO1Gy+/hQM6eI5atg/ciXvbT7rpZLZEeM39lIPN0WohD6C7XJ489W4czPj/rOnkMi04OR DVNGL/YRdy1/OxMAAdbHeP1fk73KWF7aLMPbsaYZqcmIkJz2fJ7rlmhuYE0mnch2kEv9Yg 1J2TJBm7uGAVcGLOyj6bpl7t1riDkqc= Date: Tue, 5 Aug 2025 15:32:41 -0400 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH net] net: xilinx: axienet: Increment Rx skb ring head pointer after BD is successfully allocated in dmaengine flow To: Suraj Gupta , andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, michal.simek@amd.com, radhey.shyam.pandey@amd.com, horms@kernel.org Cc: netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, harini.katakam@amd.com References: <20250805191958.412220-1-suraj.gupta2@amd.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Sean Anderson In-Reply-To: <20250805191958.412220-1-suraj.gupta2@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 8/5/25 15:19, Suraj Gupta wrote: > In DMAengine flow, AXI DMA driver invokes callback before freeing BD in > irq handling path. > In Rx callback (axienet_dma_rx_cb()), axienet driver tries to allocate > new BD after processing skb. > This will be problematic if both AXI-DMA and AXI ethernet have same > BD count as all Rx BDs will be allocated initially and it won't be > able to allocate new one after Rx irq. Incrementing head pointer w/o > checking for BD allocation will result in garbage values in skb BD and > cause the below kernel crash: > > Unable to handle kernel paging request at virtual address fffffffffffffffa > > Internal error: Oops: 0000000096000006 [#1] SMP > pc : axienet_dma_rx_cb+0x78/0x150 > lr : axienet_dma_rx_cb+0x78/0x150 > Call trace: > axienet_dma_rx_cb+0x78/0x150 (P) > xilinx_dma_do_tasklet+0xdc/0x290 > tasklet_action_common+0x12c/0x178 > tasklet_action+0x30/0x3c > handle_softirqs+0xf8/0x230 > > > Fixes: 6a91b846af85 ("net: axienet: Introduce dmaengine support") > Signed-off-by: Suraj Gupta > --- > drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c > index 6011d7eae0c7..acd5be60afec 100644 > --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c > +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c > @@ -1457,7 +1457,6 @@ static void axienet_rx_submit_desc(struct net_device *ndev) > if (!skbuf_dma) > return; > > - lp->rx_ring_head++; > skb = netdev_alloc_skb(ndev, lp->max_frm_size); > if (!skb) > return; > @@ -1482,6 +1481,7 @@ static void axienet_rx_submit_desc(struct net_device *ndev) > skbuf_dma->desc = dma_rx_desc; > dma_rx_desc->callback_param = lp; > dma_rx_desc->callback_result = axienet_dma_rx_cb; > + lp->rx_ring_head++; > dmaengine_submit(dma_rx_desc); > > return; Reviewed-by: Sean Anderson