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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4343C433F5 for ; Sat, 23 Apr 2022 00:02:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229722AbiDWAFa (ORCPT ); Fri, 22 Apr 2022 20:05:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40936 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229509AbiDWAF3 (ORCPT ); Fri, 22 Apr 2022 20:05:29 -0400 Received: from mail-ot1-x335.google.com (mail-ot1-x335.google.com [IPv6:2607:f8b0:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4283E13EA0 for ; Fri, 22 Apr 2022 17:02:34 -0700 (PDT) Received: by mail-ot1-x335.google.com with SMTP id i3-20020a056830010300b00605468119c3so6549119otp.11 for ; Fri, 22 Apr 2022 17:02:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:in-reply-to:references:from:user-agent:date:message-id :subject:to:cc; bh=qPSkwD/MU+Iqo4BRfa/Ls4gx2geTEC9xNtBW72fotns=; b=SGhKHlx9rgmGuT6KRjWdwmxQ6DjMyJuzfLXLaIeYVZ5TcfYbaSKVqoxVTgfk6REXcQ TlgPEGIZWLwT8DG8S96iFRwCNg7xVZDKb+MzzlNcrntMSloJCzacD5SpwspomRzFRT3g wgr86qCSKfNxzHpd40okIrwxExUC0sZieWPdQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:in-reply-to:references:from :user-agent:date:message-id:subject:to:cc; bh=qPSkwD/MU+Iqo4BRfa/Ls4gx2geTEC9xNtBW72fotns=; b=yw5fiJkdbIxMg3imB+rYQAuEuZ4H6oSta+JlzYmrU0zHw2DJzh9tpk+BBW2T+NBvtp C/5epv72tZCr3b7LcyYICQdGBgD9d3CmI29vTT2r4nY1PPOQ6byNf1eJYLcjtDpxh5JP EAMqjl6dvGmplL5cLQJek3fHg+z3l3hibOyakcUR1UCQ2HAv+ZgEpkEgLjyrAAEVl76Q U/81/FEM1Qe6K5gEnJlBV5dfMsHTg+Kr5x5jtqPj1UQHGt9qrnCE2BQ2kaDTsHE7BfwL O8aKNxOq/RR1V/+NGSK6YqkpVE1qGo0Igucc/QH+TegTfhqmdIsE7Ibz7q8+5rK+/XWh +mGg== X-Gm-Message-State: AOAM531gnqrqg7VD9ooRYUXURpPSJtoD661k5z9I/J4v12GZ5Qm6Fihd 0u4Soj7Dh/IR68NRidhpm8AuH2QSMmyV3skzUKDWhQ== X-Google-Smtp-Source: ABdhPJyCu1JPsTB5cEHaf/m5kBgPEh7iMzqGhHYkxVcYy1y6WXjtp50N6Ta3Ouu7RPsVdOORKVJbQT5IgWz1UxpYpbM= X-Received: by 2002:a9d:20a1:0:b0:5e8:d2b6:f63f with SMTP id x30-20020a9d20a1000000b005e8d2b6f63fmr2689805ota.159.1650672153625; Fri, 22 Apr 2022 17:02:33 -0700 (PDT) Received: from 753933720722 named unknown by gmailapi.google.com with HTTPREST; Fri, 22 Apr 2022 17:02:33 -0700 MIME-Version: 1.0 In-Reply-To: <1650671124-14030-1-git-send-email-quic_khsieh@quicinc.com> References: <1650671124-14030-1-git-send-email-quic_khsieh@quicinc.com> From: Stephen Boyd User-Agent: alot/0.10 Date: Fri, 22 Apr 2022 17:02:33 -0700 Message-ID: Subject: Re: [PATCH] drm/msm/dp: move add fail safe mode to dp_connector_get_mode() To: Kuogee Hsieh , agross@kernel.org, airlied@linux.ie, bjorn.andersson@linaro.org, daniel@ffwll.ch, dmitry.baryshkov@linaro.org, robdclark@gmail.com, sean@poorly.run, vkoul@kernel.org Cc: quic_abhinavk@quicinc.com, quic_aravindh@quicinc.com, quic_sbillaka@quicinc.com, freedreno@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Quoting Kuogee Hsieh (2022-04-22 16:45:23) > Current DP driver implementation has adding safe mode done at > dp_hpd_plug_handle() which is expected to be executed under event > thread context. > > However there is possible circular locking happen (see blow stack trace) > after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which > is executed under drm_thread context. > > To break this circular locking, this patch have safe mode added at > dp_connector_get_mode() which is executed under drm thread context. > Therefore no lock acquired required for &dev->mode_config.mutex while > adding fail safe mode since it has been hold by drm thread already. Reported-by: Douglas Anderson Fixes: 8b2c181e3dcf ("drm/msm/dp: add fail safe mode outside of event_mutex context") Reviewed-by: Stephen Boyd 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 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 068ECC433EF for ; Sat, 23 Apr 2022 00:02:36 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3919F10E27C; Sat, 23 Apr 2022 00:02:36 +0000 (UTC) Received: from mail-ot1-x32c.google.com (mail-ot1-x32c.google.com [IPv6:2607:f8b0:4864:20::32c]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5440E10E1EB for ; Sat, 23 Apr 2022 00:02:34 +0000 (UTC) Received: by mail-ot1-x32c.google.com with SMTP id k29-20020a056830243d00b006040caa0988so6565735ots.6 for ; Fri, 22 Apr 2022 17:02:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:in-reply-to:references:from:user-agent:date:message-id :subject:to:cc; bh=qPSkwD/MU+Iqo4BRfa/Ls4gx2geTEC9xNtBW72fotns=; b=SGhKHlx9rgmGuT6KRjWdwmxQ6DjMyJuzfLXLaIeYVZ5TcfYbaSKVqoxVTgfk6REXcQ TlgPEGIZWLwT8DG8S96iFRwCNg7xVZDKb+MzzlNcrntMSloJCzacD5SpwspomRzFRT3g wgr86qCSKfNxzHpd40okIrwxExUC0sZieWPdQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:in-reply-to:references:from :user-agent:date:message-id:subject:to:cc; bh=qPSkwD/MU+Iqo4BRfa/Ls4gx2geTEC9xNtBW72fotns=; b=Ne2yfDYI8N0M8RaHU1ZNIvuOexpCh+XGddQXpVaKtmNhIFW7b891nrrhjLjdWo5czp d17BYzlaPc8i3ZXgTJ0FREa64JO0d9FwJeiaZjlsDKHuzju4t9M4a00g9LOQMs1vOhq+ hVtY+sP2DZHxyeGqOo3Y0vac5vZ+/HfFMahqfIuh1mHkjjNTuaWRTi/k79mbt7aDIoHT J6telXdaWjjhPh1KEspBfJP5Qi79hhDlxqZnJZeuc/dzdVmXAEkJ5w+x4Iai0DFxHFki /FDuGlf3JBQC8gFRUYfSYuL/edfDoGG8plDFeoIYHeGRZuG1FB3CHtLxGMEftd/kISaE FlpA== X-Gm-Message-State: AOAM5312NJBCR2StGOkdO4laPks3m+sFjQMrNTL2Jp4Sdpv2+POvSzOC E0SUjF3JoGfZcG+qu8RUl86x17arvl7F1W6hWKpeNw== X-Google-Smtp-Source: ABdhPJyCu1JPsTB5cEHaf/m5kBgPEh7iMzqGhHYkxVcYy1y6WXjtp50N6Ta3Ouu7RPsVdOORKVJbQT5IgWz1UxpYpbM= X-Received: by 2002:a9d:20a1:0:b0:5e8:d2b6:f63f with SMTP id x30-20020a9d20a1000000b005e8d2b6f63fmr2689805ota.159.1650672153625; Fri, 22 Apr 2022 17:02:33 -0700 (PDT) Received: from 753933720722 named unknown by gmailapi.google.com with HTTPREST; Fri, 22 Apr 2022 17:02:33 -0700 MIME-Version: 1.0 In-Reply-To: <1650671124-14030-1-git-send-email-quic_khsieh@quicinc.com> References: <1650671124-14030-1-git-send-email-quic_khsieh@quicinc.com> From: Stephen Boyd User-Agent: alot/0.10 Date: Fri, 22 Apr 2022 17:02:33 -0700 Message-ID: Subject: Re: [PATCH] drm/msm/dp: move add fail safe mode to dp_connector_get_mode() To: Kuogee Hsieh , agross@kernel.org, airlied@linux.ie, bjorn.andersson@linaro.org, daniel@ffwll.ch, dmitry.baryshkov@linaro.org, robdclark@gmail.com, sean@poorly.run, vkoul@kernel.org Content-Type: text/plain; charset="UTF-8" X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: quic_sbillaka@quicinc.com, linux-arm-msm@vger.kernel.org, quic_abhinavk@quicinc.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, quic_aravindh@quicinc.com, freedreno@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Quoting Kuogee Hsieh (2022-04-22 16:45:23) > Current DP driver implementation has adding safe mode done at > dp_hpd_plug_handle() which is expected to be executed under event > thread context. > > However there is possible circular locking happen (see blow stack trace) > after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which > is executed under drm_thread context. > > To break this circular locking, this patch have safe mode added at > dp_connector_get_mode() which is executed under drm thread context. > Therefore no lock acquired required for &dev->mode_config.mutex while > adding fail safe mode since it has been hold by drm thread already. Reported-by: Douglas Anderson Fixes: 8b2c181e3dcf ("drm/msm/dp: add fail safe mode outside of event_mutex context") Reviewed-by: Stephen Boyd