From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C9D1EEED60A for ; Thu, 12 Sep 2024 14:35:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=DTWJHgLcn4spfm5GWguWcfzJyLphgl0AC6/fahz7z7s=; b=qpAUQGoHEKyAe+3pqtfmLTLFEr bL0EX2xzpQL9xe4qoHoMc1epKFEQjs0jvm2+cIkMfdLcIOcptiKVpsi0F8m+8cwq3kUA1yk48GiY0 7avT3dhnbRowXIPaLKPVjCpUW4EQM3EKvuLpqOHTS5p2dWv0b70+DfnzmXClz61VDlbBhDode4Lst UvxUtznOuuPEnIQuTUjYA3azfUePCX7fmaW8+z+HRo4fu8vYAfh7KL8mBrwTYOAqOxwllHesQv2h8 UxpURJcCsZSNdB/kqGvg64U4KfDIt1xC6ME+PAH68W8JTNqddAq+6VCgxd/HMeqsJa9qIH4nOfpcR ki3pVx0A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sokuM-0000000DNAr-0ePE; Thu, 12 Sep 2024 14:34:54 +0000 Received: from out-178.mta1.migadu.com ([95.215.58.178]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sokqi-0000000DMH2-1mVx for linux-arm-kernel@lists.infradead.org; Thu, 12 Sep 2024 14:31:11 +0000 Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1726151461; 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=DTWJHgLcn4spfm5GWguWcfzJyLphgl0AC6/fahz7z7s=; b=uOJ2ES/ilsYa2yEI8S6LOlrkwIJQRzu8stg2al7F72G1f34CLeR4F4Rus9F2R+FJm7+I3z noe7cDxmJwwWVLTBkvYVDk8Yh4dqfmLIl6F2NZKJ08tejvHA7gc8q2TUCn2/uexXbVqQvv 9xuMwfzRaSdsf+DRUBI7OfkCC4Ha0Po= Date: Thu, 12 Sep 2024 10:30:56 -0400 MIME-Version: 1.0 Subject: Re: [PATCH net v2] net: xilinx: axienet: Fix IRQ coalescing packet count overflow To: "Pandey, Radhey Shyam" , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , "netdev@vger.kernel.org" , "Gupta, Suraj" , "Katakam, Harini" Cc: Andy Chiu , "linux-kernel@vger.kernel.org" , Simon Horman , Ariane Keller , Daniel Borkmann , "linux-arm-kernel@lists.infradead.org" , "Simek, Michal" References: <20240909230908.1319982-1-sean.anderson@linux.dev> 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240912_073108_795539_A4680083 X-CRM114-Status: GOOD ( 23.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 9/11/24 03:01, Pandey, Radhey Shyam wrote: >> -----Original Message----- >> From: Sean Anderson >> Sent: Tuesday, September 10, 2024 4:39 AM >> To: Pandey, Radhey Shyam ; David S . >> Miller ; Eric Dumazet ; >> Jakub Kicinski ; Paolo Abeni ; >> netdev@vger.kernel.org >> Cc: Andy Chiu ; linux-kernel@vger.kernel.org; Simon >> Horman ; Ariane Keller ; >> Daniel Borkmann ; linux-arm- >> kernel@lists.infradead.org; Simek, Michal ; Sean >> Anderson >> Subject: [PATCH net v2] net: xilinx: axienet: Fix IRQ coalescing packet count >> overflow >> >> If coalece_count is greater than 255 it will not fit in the register and >> will overflow. This can be reproduced by running >> >> # ethtool -C ethX rx-frames 256 >> >> which will result in a timeout of 0us instead. Fix this by clamping the >> counts to the maximum value. > After this fix - what is o/p we get on rx-frames read? I think silent clamping is not a great > idea and user won't know about it. One alternative is to add check in set_coalesc > count for valid range? (Similar to axienet_ethtools_set_ringparam so that user is notified > for incorrect range) The value reported will be unclamped. In [1] I improve the driver to return the actual (clamped) value. Remember that without this commit, we have silent wraparound instead. I think clamping is much friendlier, since you at least get something close to the rx-frames value, instead of zero! This commit is just a fix for the overflow issue. To ensure it is appropriate for backporting I have omitted any other changes/improvements. --Sean [1] https://lore.kernel.org/netdev/20240909235208.1331065-6-sean.anderson@linux.dev/ >> >> Signed-off-by: Sean Anderson >> Fixes: 8a3b7a252dca ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet >> driver") >> --- >> >> Changes in v2: >> - Use FIELD_MAX to extract the max value from the mask >> - Expand the commit message with an example on how to reproduce this >> issue >> >> drivers/net/ethernet/xilinx/xilinx_axienet.h | 5 ++--- >> drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 8 ++++++-- >> 2 files changed, 8 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h >> b/drivers/net/ethernet/xilinx/xilinx_axienet.h >> index 1223fcc1a8da..54db69893565 100644 >> --- a/drivers/net/ethernet/xilinx/xilinx_axienet.h >> +++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h >> @@ -109,11 +109,10 @@ >> #define XAXIDMA_BD_CTRL_TXEOF_MASK 0x04000000 /* Last tx packet >> */ >> #define XAXIDMA_BD_CTRL_ALL_MASK 0x0C000000 /* All control bits >> */ >> >> -#define XAXIDMA_DELAY_MASK 0xFF000000 /* Delay timeout >> counter */ >> -#define XAXIDMA_COALESCE_MASK 0x00FF0000 /* Coalesce >> counter */ >> +#define XAXIDMA_DELAY_MASK ((u32)0xFF000000) /* Delay >> timeout counter */ > > Adding typecast here looks odd. Any reason for it? > If needed we do it in specific case where it is required. > >> +#define XAXIDMA_COALESCE_MASK ((u32)0x00FF0000) /* >> Coalesce counter */ >> >> #define XAXIDMA_DELAY_SHIFT 24 >> -#define XAXIDMA_COALESCE_SHIFT 16 >> >> #define XAXIDMA_IRQ_IOC_MASK 0x00001000 /* Completion >> intr */ >> #define XAXIDMA_IRQ_DELAY_MASK 0x00002000 /* Delay >> interrupt */ >> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c >> b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c >> index 9eb300fc3590..89b63695293d 100644 >> --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c >> +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c >> @@ -252,7 +252,9 @@ static u32 axienet_usec_to_timer(struct axienet_local >> *lp, u32 coalesce_usec) >> static void axienet_dma_start(struct axienet_local *lp) >> { >> /* Start updating the Rx channel control register */ >> - lp->rx_dma_cr = (lp->coalesce_count_rx << >> XAXIDMA_COALESCE_SHIFT) | >> + lp->rx_dma_cr = FIELD_PREP(XAXIDMA_COALESCE_MASK, >> + min(lp->coalesce_count_rx, >> + >> FIELD_MAX(XAXIDMA_COALESCE_MASK))) | >> XAXIDMA_IRQ_IOC_MASK | >> XAXIDMA_IRQ_ERROR_MASK; >> /* Only set interrupt delay timer if not generating an interrupt on >> * the first RX packet. Otherwise leave at 0 to disable delay interrupt. >> @@ -264,7 +266,9 @@ static void axienet_dma_start(struct axienet_local >> *lp) >> axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, lp->rx_dma_cr); >> >> /* Start updating the Tx channel control register */ >> - lp->tx_dma_cr = (lp->coalesce_count_tx << >> XAXIDMA_COALESCE_SHIFT) | >> + lp->tx_dma_cr = FIELD_PREP(XAXIDMA_COALESCE_MASK, >> + min(lp->coalesce_count_tx, >> + >> FIELD_MAX(XAXIDMA_COALESCE_MASK))) | >> XAXIDMA_IRQ_IOC_MASK | >> XAXIDMA_IRQ_ERROR_MASK; >> /* Only set interrupt delay timer if not generating an interrupt on >> * the first TX packet. Otherwise leave at 0 to disable delay interrupt. >> -- >> 2.35.1.1320.gc452695387.dirty >