From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:39050 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934716AbeDKTDm (ORCPT ); Wed, 11 Apr 2018 15:03:42 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Netanel Belgazal , "David S. Miller" , Sasha Levin Subject: [PATCH 4.9 241/310] net: ena: fix rare uncompleted admin command false alarm Date: Wed, 11 Apr 2018 20:36:20 +0200 Message-Id: <20180411183632.847583014@linuxfoundation.org> In-Reply-To: <20180411183622.305902791@linuxfoundation.org> References: <20180411183622.305902791@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Netanel Belgazal [ Upstream commit a77c1aafcc906f657d1a0890c1d898be9ee1d5c9 ] The current flow to detect admin completion is: while (command_not_completed) { if (timeout) error check_for_completion() sleep() } So in case the sleep took more than the timeout (in case the thread/workqueue was not scheduled due to higher priority task or prolonged VMexit), the driver can detect a stall even if the completion is present. The fix changes the order of this function to first check for completion and only after that check if the timeout expired. Fixes: 1738cd3ed342 ("Add a driver for Amazon Elastic Network Adapters (ENA)") Signed-off-by: Netanel Belgazal Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/amazon/ena/ena_com.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) --- a/drivers/net/ethernet/amazon/ena/ena_com.c +++ b/drivers/net/ethernet/amazon/ena/ena_com.c @@ -508,15 +508,20 @@ static int ena_com_comp_status_to_errno( static int ena_com_wait_and_process_admin_cq_polling(struct ena_comp_ctx *comp_ctx, struct ena_com_admin_queue *admin_queue) { - unsigned long flags; - u32 start_time; + unsigned long flags, timeout; int ret; - start_time = ((u32)jiffies_to_usecs(jiffies)); + timeout = jiffies + ADMIN_CMD_TIMEOUT_US; - while (comp_ctx->status == ENA_CMD_SUBMITTED) { - if ((((u32)jiffies_to_usecs(jiffies)) - start_time) > - ADMIN_CMD_TIMEOUT_US) { + while (1) { + spin_lock_irqsave(&admin_queue->q_lock, flags); + ena_com_handle_admin_completion(admin_queue); + spin_unlock_irqrestore(&admin_queue->q_lock, flags); + + if (comp_ctx->status != ENA_CMD_SUBMITTED) + break; + + if (time_is_before_jiffies(timeout)) { pr_err("Wait for completion (polling) timeout\n"); /* ENA didn't have any completion */ spin_lock_irqsave(&admin_queue->q_lock, flags); @@ -528,10 +533,6 @@ static int ena_com_wait_and_process_admi goto err; } - spin_lock_irqsave(&admin_queue->q_lock, flags); - ena_com_handle_admin_completion(admin_queue); - spin_unlock_irqrestore(&admin_queue->q_lock, flags); - msleep(100); }