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 1201C2E11B9; Mon, 13 Apr 2026 16:26:32 +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=1776097592; cv=none; b=gS3AvQOVMWi7qtuKqVQaTH8unWqg19Ez4/56pm76qSYYUvuz2SWuhxKJDl1l2kMeGXPyxfpK8jQnfH3zvLekLywQkvTxuJx9QlqbAiZpHu58QPeZBozp+T0SM6k0eNps1AHRASpn3mT0mSFA7KHBviz2VUbP5b6uFlh5FSnff8A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776097592; c=relaxed/simple; bh=Na0XhSMZzUdwlhxDpnLvWa3H0DwUaMn/4OeY6rmPRUA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SBWZxEyJLqzkKJ/WH5PVc2fEDALg6ZKvUprYUttuMnO6QS3YFiVwXoDe+SZsb+WWVDpcJ49tddZONcPvtR2uDKFm1SKfUXNIHtLo65rRbWq4uxk532ghOjJAHKesvyCOwT5KR99LK76R06BETLiQ4NtghyQNpUy1Ogrz2myZggA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YPKkkDcB; 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="YPKkkDcB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B65AC2BCAF; Mon, 13 Apr 2026 16:26:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776097592; bh=Na0XhSMZzUdwlhxDpnLvWa3H0DwUaMn/4OeY6rmPRUA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YPKkkDcBuEmAcvG66n4vNO0OSr1uFUbFq0WCz5ItGyDKaE3YXJxjysZRSqtNTHvII VPPeQZ1AcL9TX29/7bgch5spZLztLcfyJlCsh7eLL+iwJ4WaqYL5vbbly3Si8+hluT QBWGKMxmbWwBeHZfc5BHTeF22wbcZidJp5tTBYa4= 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 5.15 164/570] net: mana: Ring doorbell at 4 CQ wraparounds Date: Mon, 13 Apr 2026 17:54:55 +0200 Message-ID: <20260413155836.593906334@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413155830.386096114@linuxfoundation.org> References: <20260413155830.386096114@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-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 @@ -798,8 +798,14 @@ 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; @@ -1056,7 +1062,14 @@ static void mana_poll_rx_cq(struct mana_ struct gdma_comp *comp = cq->gdma_comp_buf; 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); for (i = 0; i < comp_read; i++) { @@ -1090,11 +1103,11 @@ 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);