From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AA5C0C48BE5 for ; Tue, 22 Jun 2021 02:35:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 80D826052B for ; Tue, 22 Jun 2021 02:35:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231322AbhFVCho (ORCPT ); Mon, 21 Jun 2021 22:37:44 -0400 Received: from m43-7.mailgun.net ([69.72.43.7]:43653 "EHLO m43-7.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231196AbhFVChn (ORCPT ); Mon, 21 Jun 2021 22:37:43 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1624329328; h=Message-Id: Date: Subject: Cc: To: From: Sender; bh=IG4TSyrksizFymZrnKCgKZ+EJpwEDN3w0qluXMi0ZD8=; b=OMe/mLsshUwBKsJJfT3WIRQmTxAwi4SbbKJWPMzwSKUOYb1rFa2FBuyfAlbooVqpNdW8fUCS F6QJE75Hs9dG7otLdij1nRe/tfJZMlIJVxb+dbgv6+UP6dHTLLF+oZbvcyAibvGyauazSZMz sxeIk6ulsCELg9tmoR4JYU5Ogo0= X-Mailgun-Sending-Ip: 69.72.43.7 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n06.prod.us-west-2.postgun.com with SMTP id 60d14c5c8491191eb30a0792 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 22 Jun 2021 02:35:08 GMT Sender: bbhatt=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 9891EC43217; Tue, 22 Jun 2021 02:35:08 +0000 (UTC) Received: from malabar-linux.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: bbhatt) by smtp.codeaurora.org (Postfix) with ESMTPSA id 79A33C433F1; Tue, 22 Jun 2021 02:35:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 79A33C433F1 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=bbhatt@codeaurora.org From: Bhaumik Bhatt To: manivannan.sadhasivam@linaro.org Cc: linux-arm-msm@vger.kernel.org, hemantk@codeaurora.org, jhugo@codeaurora.org, linux-kernel@vger.kernel.org, loic.poulain@linaro.org, Bhaumik Bhatt Subject: [PATCH v2] bus: mhi: core: Disable pre-emption for events tasklet processing Date: Mon, 21 Jun 2021 19:34:52 -0700 Message-Id: <1624329292-27092-1-git-send-email-bbhatt@codeaurora.org> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With spin_lock_bh(), it is possible that a tasklet processing data events gets pre-empted by RT tasks or a storm of threaded interrupt handlers ready to run on that core. While the tasklet gets scheduled out, it can hold the event ring spinlock and block another tasklet, for example, one processing an M0 state change event, from acquiring it. This can starve the core which blocks in an attempt to acquire the spinlock until it gets released. Fix the issue by disabling pre-emption on the core processing data events and allow the tasklet to run to completion such that other tasklets do not block on it for long periods. Fixes: 1d3173a3bae7 ("bus: mhi: core: Add support for processing events from client device") Signed-off-by: Bhaumik Bhatt --- v2: -Updated description to clarify the scenario drivers/bus/mhi/core/main.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c index 3775c77..02c8c09 100644 --- a/drivers/bus/mhi/core/main.c +++ b/drivers/bus/mhi/core/main.c @@ -1036,11 +1036,12 @@ void mhi_ev_task(unsigned long data) { struct mhi_event *mhi_event = (struct mhi_event *)data; struct mhi_controller *mhi_cntrl = mhi_event->mhi_cntrl; + unsigned long flags; /* process all pending events */ - spin_lock_bh(&mhi_event->lock); + spin_lock_irqsave(&mhi_event->lock, flags); mhi_event->process_event(mhi_cntrl, mhi_event, U32_MAX); - spin_unlock_bh(&mhi_event->lock); + spin_unlock_irqrestore(&mhi_event->lock, flags); } void mhi_ctrl_ev_task(unsigned long data) -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project