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 F41E937B3F6; Tue, 17 Mar 2026 17:22:56 +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=1773768177; cv=none; b=D/2MOU9htjhj5NgxkhYvputw99yq+/a6bPKGfybPyNFqWzeWAyDbuq65CIMDyXprJPxmfRr4Z1etAIL/hzWd3yPtPuh7j3G3Q3NqpMR/9ZdWnNfc5R5o4Pqn7MZGQhvLFNiwpude3WcF7/yvQL8p+5QYizfg27Yl1hKvHA17CI8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773768177; c=relaxed/simple; bh=TJmGLVF7UFQbGOxZIK33wtZW1gXhVwQ4wD6tYfuemec=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YpGEfCQ/DoZReG0gCxQ+Xnm/usCCRAylkp6arCa8rWdS65dPiN1FjEQCbCocTpdKNQfQuwljtR95MHai18jC4iJQyuP2UkH/KfpmQsLLXlSUcgS2L9Afn8a23ACpS7fePW7XTrmqK4nMV0WaADj7HodwUU4zbfhEw0q+yRzLlzE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=joEvDdV+; 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="joEvDdV+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 339B1C4CEF7; Tue, 17 Mar 2026 17:22:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1773768176; bh=TJmGLVF7UFQbGOxZIK33wtZW1gXhVwQ4wD6tYfuemec=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=joEvDdV+k690MDx7HJmeZkz+SXueGQeqTnvlRQGxkLVoPtf/2Ri+3vA8S4ULCHu5O ZeYTf5sLEW4F9mn+XGzZ97Yq8BKQy+s3vbCtxkiPjDmGXq8Hc04wIM2QvJmk/oQf3O DiBjoFowPrJ430Ni38+sxZUi18kmeuGioxpPhqvA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Long Li , Haiyang Zhang , Vadim Fedorenko , Jakub Kicinski Subject: [PATCH 6.18 216/333] net: mana: Ring doorbell at 4 CQ wraparounds Date: Tue, 17 Mar 2026 17:34:05 +0100 Message-ID: <20260317163007.373345597@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260317162959.345812316@linuxfoundation.org> References: <20260317162959.345812316@linuxfoundation.org> User-Agent: quilt/0.69 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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Long Li commit dabffd08545ffa1d7183bc45e387860984025291 upstream. MANA hardware requires at least one doorbell ring every 8 wraparounds of the CQ. The driver rings the doorbell as a form of flow control to inform hardware that CQEs have been consumed. The NAPI poll functions mana_poll_tx_cq() and mana_poll_rx_cq() can poll up to CQE_POLLING_BUFFER (512) completions per call. If the CQ has fewer than 512 entries, a single poll call can process more than 4 wraparounds without ringing the doorbell. The doorbell threshold check also uses ">" instead of ">=", delaying the ring by one extra CQE beyond 4 wraparounds. Combined, these issues can cause the driver to exceed the 8-wraparound hardware limit, leading to missed completions and stalled queues. Fix this by capping the number of CQEs polled per call to 4 wraparounds of the CQ in both TX and RX paths. Also change the doorbell threshold from ">" to ">=" so the doorbell is rung as soon as 4 wraparounds are reached. Cc: stable@vger.kernel.org Fixes: 58a63729c957 ("net: mana: Fix doorbell out of order violation and avoid unnecessary doorbell rings") Signed-off-by: Long Li Reviewed-by: Haiyang Zhang Reviewed-by: Vadim Fedorenko Link: https://patch.msgid.link/20260226192833.1050807-1-longli@microsoft.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/microsoft/mana/mana_en.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) --- a/drivers/net/ethernet/microsoft/mana/mana_en.c +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c @@ -1645,8 +1645,14 @@ static void mana_poll_tx_cq(struct mana_ ndev = txq->ndev; apc = netdev_priv(ndev); + /* Limit CQEs polled to 4 wraparounds of the CQ to ensure the + * doorbell can be rung in time for the hardware's requirement + * of at least one doorbell ring every 8 wraparounds. + */ comp_read = mana_gd_poll_cq(cq->gdma_cq, completions, - CQE_POLLING_BUFFER); + min((cq->gdma_cq->queue_size / + COMP_ENTRY_SIZE) * 4, + CQE_POLLING_BUFFER)); if (comp_read < 1) return; @@ -2031,7 +2037,14 @@ static void mana_poll_rx_cq(struct mana_ struct mana_rxq *rxq = cq->rxq; int comp_read, i; - comp_read = mana_gd_poll_cq(cq->gdma_cq, comp, CQE_POLLING_BUFFER); + /* Limit CQEs polled to 4 wraparounds of the CQ to ensure the + * doorbell can be rung in time for the hardware's requirement + * of at least one doorbell ring every 8 wraparounds. + */ + comp_read = mana_gd_poll_cq(cq->gdma_cq, comp, + min((cq->gdma_cq->queue_size / + COMP_ENTRY_SIZE) * 4, + CQE_POLLING_BUFFER)); WARN_ON_ONCE(comp_read > CQE_POLLING_BUFFER); rxq->xdp_flush = false; @@ -2076,11 +2089,11 @@ static int mana_cq_handler(void *context mana_gd_ring_cq(gdma_queue, SET_ARM_BIT); cq->work_done_since_doorbell = 0; napi_complete_done(&cq->napi, w); - } else if (cq->work_done_since_doorbell > - cq->gdma_cq->queue_size / COMP_ENTRY_SIZE * 4) { + } else if (cq->work_done_since_doorbell >= + (cq->gdma_cq->queue_size / COMP_ENTRY_SIZE) * 4) { /* MANA hardware requires at least one doorbell ring every 8 * wraparounds of CQ even if there is no need to arm the CQ. - * This driver rings the doorbell as soon as we have exceeded + * This driver rings the doorbell as soon as it has processed * 4 wraparounds. */ mana_gd_ring_cq(gdma_queue, 0);