From patchwork Fri Jun 18 22:23:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bhaumik Bhatt X-Patchwork-Id: 12332249 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=-16.8 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=ham 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 D8F86C48BDF for ; Fri, 18 Jun 2021 22:23:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A432260E0B for ; Fri, 18 Jun 2021 22:23:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234829AbhFRWZb (ORCPT ); Fri, 18 Jun 2021 18:25:31 -0400 Received: from m43-7.mailgun.net ([69.72.43.7]:53627 "EHLO m43-7.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234826AbhFRWZb (ORCPT ); Fri, 18 Jun 2021 18:25:31 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1624055001; h=Message-Id: Date: Subject: Cc: To: From: Sender; bh=ubzEVrSdPA3vjYU/6eZRiUqOhwzl9y2ios8I9n7VFPw=; b=ttIUEPlyTlLkxH0oT42Lnj3tQNuVUUySDXKrU4/rntlZY/zZ4Da/Bog1V/TC9lLxm9blpqZc GdwIIvVxOxoJkFufcw2nKlWvdsiycKMt3E6gxMPZ6mK8CqniD6jNm9J4yVIvN7/HIXCGwrpy fc4e8kElfLSqWB4EE4/3vKLazrk= X-Mailgun-Sending-Ip: 69.72.43.7 X-Mailgun-Sid: WyI1MzIzYiIsICJsaW51eC1hcm0tbXNtQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n07.prod.us-west-2.postgun.com with SMTP id 60cd1cd4ea2aacd7291bdf36 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Fri, 18 Jun 2021 22:23:16 GMT Sender: bbhatt=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id D694DC43460; Fri, 18 Jun 2021 22:23:15 +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 B80F9C433D3; Fri, 18 Jun 2021 22:23:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org B80F9C433D3 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] bus: mhi: core: Disable pre-emption for data events tasklet processing Date: Fri, 18 Jun 2021 15:23:05 -0700 Message-Id: <1624054985-31365-1-git-send-email-bbhatt@codeaurora.org> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org With spin_lock_bh(), it is possible that a tasklet processing data events gets scheduled out if another higher priority tasklet is ready to run. While the tasklet is sleeping, 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 this issue by disabling pre-emption on the core processing data events and allow it to run to completion such that other tasklets do not block for long periods. Fixes: 1d3173a3bae7 ("bus: mhi: core: Add support for processing events from client device") Signed-off-by: Bhaumik Bhatt --- 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)