From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B4BDF2FFDC4; Tue, 12 Aug 2025 18:42:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755024128; cv=none; b=BDvfOVaWZYD/BJgwd/LRStMZEbL1yLJCq+yqfjgeh23eK3FM17zWCa/fveH4JN/7UQMRjXHFJoTJdC9wkAG7DzA2B6fMR5M2FnQrqgSS3zfI53ealE0oVH7XwiT3jhPyKPCQoOiRFMfHHCsYkxUhhqjjl+gQ3bIByGfuO4uTriY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755024128; c=relaxed/simple; bh=cKgxaqmX4GQJuJoXMdxTVA7bvSvWWm7EjnV2l1heMHY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OJJetzSf3p6UC2SNVJh06et5AKy/PXeNQqFVskBpV5Wn407UaX6/upi1D7BuEoRsqa5ZWpVQqDvZZxwHOamB5KQ1fyGEQlwWk4sf4QkKyfYOiZNeju197dFBEG2HiAWXUKkGsAE+jA4VuvHn+S3tKQrJ1m8wt4VmUImIvs7uNHs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=eB85Tlxk; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="eB85Tlxk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 16460C4CEF0; Tue, 12 Aug 2025 18:42:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755024128; bh=cKgxaqmX4GQJuJoXMdxTVA7bvSvWWm7EjnV2l1heMHY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eB85Tlxk5qD81vaFLecxE6Es5Ca5lbyc86U+OuZsslr9OlVadgNNtKxlASws13Mxe MXkUKrPxRUbEKAGospZXAW+Ddv3KVrbnEF79BiK1OASve8s+QylOEe+U+DpjGU6Dhh BzrzI/V/rZUpX0sc2rTG+RN7RcRMHlrsg/oQBUbg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jason Xing , Aleksandr Loktionov , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.16 283/627] igb: xsk: solve negative overflow of nb_pkts in zerocopy mode Date: Tue, 12 Aug 2025 19:29:38 +0200 Message-ID: <20250812173430.082383238@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250812173419.303046420@linuxfoundation.org> References: <20250812173419.303046420@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Xing [ Upstream commit 3b7c13dfdcc26a78756cc17a23cdf4310c5a24a9 ] There is no break time in the while() loop, so every time at the end of igb_xmit_zc(), negative overflow of nb_pkts will occur, which renders the return value always false. But theoretically, the result should be set after calling xsk_tx_peek_release_desc_batch(). We can take i40e_xmit_zc() as a good example. Returning false means we're not done with transmission and we need one more poll, which is exactly what igb_xmit_zc() always did before this patch. After this patch, the return value depends on the nb_pkts value. Two cases might happen then: 1. if (nb_pkts < budget), it means we process all the possible data, so return true and no more necessary poll will be triggered because of this. 2. if (nb_pkts == budget), it means we might have more data, so return false to let another poll run again. Fixes: f8e284a02afc ("igb: Add AF_XDP zero-copy Tx support") Signed-off-by: Jason Xing Reviewed-by: Aleksandr Loktionov Link: https://patch.msgid.link/20250723142327.85187-3-kerneljasonxing@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/ethernet/intel/igb/igb_xsk.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/igb/igb_xsk.c b/drivers/net/ethernet/intel/igb/igb_xsk.c index 5cf67ba29269..30ce5fbb5b77 100644 --- a/drivers/net/ethernet/intel/igb/igb_xsk.c +++ b/drivers/net/ethernet/intel/igb/igb_xsk.c @@ -482,7 +482,7 @@ bool igb_xmit_zc(struct igb_ring *tx_ring, struct xsk_buff_pool *xsk_pool) if (!nb_pkts) return true; - while (nb_pkts-- > 0) { + for (; i < nb_pkts; i++) { dma = xsk_buff_raw_get_dma(xsk_pool, descs[i].addr); xsk_buff_raw_dma_sync_for_device(xsk_pool, dma, descs[i].len); @@ -512,7 +512,6 @@ bool igb_xmit_zc(struct igb_ring *tx_ring, struct xsk_buff_pool *xsk_pool) total_bytes += descs[i].len; - i++; tx_ring->next_to_use++; tx_buffer_info->next_to_watch = tx_desc; if (tx_ring->next_to_use == tx_ring->count) -- 2.39.5