From patchwork Mon Mar 4 09:01:24 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Brandes, Shai" X-Patchwork-Id: 137861 X-Patchwork-Delegate: ferruh.yigit@amd.com Return-Path: X-Original-To: patchwork@inbox.dpdk.org Delivered-To: patchwork@inbox.dpdk.org Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id C094043B9B; Mon, 4 Mar 2024 10:05:32 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 475294068E; Mon, 4 Mar 2024 10:02:22 +0100 (CET) Received: from smtp-fw-2101.amazon.com (smtp-fw-2101.amazon.com [72.21.196.25]) by mails.dpdk.org (Postfix) with ESMTP id 10D0842DC1 for ; Mon, 4 Mar 2024 10:02:12 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1709542933; x=1741078933; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version; bh=0XB/vlTsLxhbBKVlP/A9n00Gi+AxEmYSIH226VxO5mY=; b=QAdzFSjnnzgvNewxJjGuxvFbUrTMIPETPnbSWW3qMg+qr5JxM42aevKo 3xi+r0u8HYk5iar676ISGdThh6WfDDCCJTBy3ZuWCTcWwnadzZnMeJszi PpNHN15UD4ay6e049gHyJ8HXVlW6/DUgoz3HNTwpKRqow2NMYwpficKoF 4=; X-IronPort-AV: E=Sophos;i="6.06,203,1705363200"; d="scan'208";a="385227058" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO smtpout.prod.us-east-1.prod.farcaster.email.amazon.dev) ([10.43.8.6]) by smtp-border-fw-2101.iad2.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2024 09:02:12 +0000 Received: from EX19MTAEUB001.ant.amazon.com [10.0.43.254:33091] by smtpin.naws.eu-west-1.prod.farcaster.email.amazon.dev [10.0.42.123:2525] with esmtp (Farcaster) id 9b68c575-9c11-4060-9d11-432b398eddf7; Mon, 4 Mar 2024 09:02:11 +0000 (UTC) X-Farcaster-Flow-ID: 9b68c575-9c11-4060-9d11-432b398eddf7 Received: from EX19D007EUA002.ant.amazon.com (10.252.50.68) by EX19MTAEUB001.ant.amazon.com (10.252.51.26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.28; Mon, 4 Mar 2024 09:02:11 +0000 Received: from EX19MTAUEC001.ant.amazon.com (10.252.135.222) by EX19D007EUA002.ant.amazon.com (10.252.50.68) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.28; Mon, 4 Mar 2024 09:02:11 +0000 Received: from HFA15-CG15235BS.amazon.com (10.1.212.49) by mail-relay.amazon.com (10.252.135.200) with Microsoft SMTP Server id 15.2.1258.28 via Frontend Transport; Mon, 4 Mar 2024 09:02:10 +0000 From: To: CC: , Shai Brandes Subject: [PATCH 21/33] net/ena/hal: modify memory barrier comment Date: Mon, 4 Mar 2024 11:01:24 +0200 Message-ID: <20240304090136.861-22-shaibran@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20240304090136.861-1-shaibran@amazon.com> References: <20240304090136.861-1-shaibran@amazon.com> MIME-Version: 1.0 X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org From: Shai Brandes The dma_rmb() memory barrier guarantees that the device set the phase bit before continuing to read the rest of the descriptor. Because the phase bit and the rest of the descriptor are in the same cache line this ensures coherency of the data from the descriptor. Signed-off-by: Shai Brandes Reviewed-by: Amit Bernstein --- drivers/net/ena/hal/ena_com.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ena/hal/ena_com.c b/drivers/net/ena/hal/ena_com.c index 7a23881667..7f0e0b2449 100644 --- a/drivers/net/ena/hal/ena_com.c +++ b/drivers/net/ena/hal/ena_com.c @@ -2412,8 +2412,8 @@ void ena_com_aenq_intr_handler(struct ena_com_dev *ena_dev, void *data) /* Go over all the events */ while ((READ_ONCE8(aenq_common->flags) & ENA_ADMIN_AENQ_COMMON_DESC_PHASE_MASK) == phase) { - /* Make sure the phase bit (ownership) is as expected before - * reading the rest of the descriptor. + /* Make sure the device finished writing the rest of the descriptor + * before reading it. */ dma_rmb();