From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELttTYab30X4fwlFnf+pmlh6jB5d4PSyVWL82UjeTr4VdeAjUoergGSecgJMl3sL1yWwjP8i ARC-Seal: i=1; a=rsa-sha256; t=1520955477; cv=none; d=google.com; s=arc-20160816; b=QA7VBK4vpujAaAsYjaoMpDiDNmjwuJyWA4c2sD9v8XB1naD4gEXX4qNsiIqEfTotP8 QwkVz1bQLzqXgVa3p6yD5NDvPf92oTw6jYgeaU5yY8MZdvAU0yfgJrNAHDHE5/LxWrcW 0Fq+xLh8kZY08vEBImABrC0ow3xLGfdAH4vUZm5PG4Mba+ftUHPpNK5IItes7T8rVgo3 lFR1XDTdGOSpPV54yukYX+ZXft9SK4LoYVt3XhLGmKhjsGyneuxQuchNKnyp1fQN4pPx u4mV3rtnEuIsGKyJGOMmINUkuQEjP0wfGateR06BMUWYaUvvbPBxm3yFtYIuf5pNAZbF mEFA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=5bn7jQGXNDlENiCbNnWFyxZUVP5pDvLADoQhGmUZoW4=; b=tAzRgy6A1bvizlRZmNgU9qhI6R7Jv1FXdxl0TK9mmDDHndlwy5tVfwnc4B3bKMRXjs kvM3TKnhDR8RmsrEAODRPV/haDXLjw7UOwjDD/uXAttcXi2mI0z3up2If09eikApVzJY zp5mw12O1qapivZVCr5pTPI4Jghm7qNKEiHTMj/zUBE1+8LM0nHsG8dy2BMZBhbU34Tk MwfxlpjWZj+r36xJ9yT9zB96M01RmHqMPvou/kRjd3o1YLnQ9jAiRRVZHfBzssM6LrF7 /TgzpxD9QJoZjF0pAi7enmA+ZWYqMzSvAMpCTQhSNz7aJZtsCKJ4XnalEYdSd6uCWimp QUdQ== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ben Skeggs , Dave Airlie , Lyude Paul , Lukas Wunner Subject: [PATCH 4.14 063/140] drm/nouveau: Fix deadlock on runtime suspend Date: Tue, 13 Mar 2018 16:24:26 +0100 Message-Id: <20180313152502.457394455@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180313152458.201155692@linuxfoundation.org> References: <20180313152458.201155692@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1594836807146444009?= X-GMAIL-MSGID: =?utf-8?q?1594837410343565321?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lukas Wunner commit d61a5c1063515e855bedb1b81e20e50b0ac3541e upstream. nouveau's ->runtime_suspend hook calls drm_kms_helper_poll_disable(), which waits for the output poll worker to finish if it's running. The output poll worker meanwhile calls pm_runtime_get_sync() in nouveau_connector_detect() which waits for the ongoing suspend to finish, causing a deadlock. Fix by not acquiring a runtime PM ref if nouveau_connector_detect() is called in the output poll worker's context. This is safe because the poll worker is only enabled while runtime active and we know that ->runtime_suspend waits for it to finish. Other contexts calling nouveau_connector_detect() do require a runtime PM ref, these comprise: status_store() drm sysfs interface ->fill_modes drm callback drm_fb_helper_probe_connector_modes() drm_mode_getconnector() nouveau_connector_hotplug() nouveau_display_hpd_work() nv17_tv_set_property() Stack trace for posterity: INFO: task kworker/0:1:58 blocked for more than 120 seconds. Workqueue: events output_poll_execute [drm_kms_helper] Call Trace: schedule+0x28/0x80 rpm_resume+0x107/0x6e0 __pm_runtime_resume+0x47/0x70 nouveau_connector_detect+0x7e/0x4a0 [nouveau] nouveau_connector_detect_lvds+0x132/0x180 [nouveau] drm_helper_probe_detect_ctx+0x85/0xd0 [drm_kms_helper] output_poll_execute+0x11e/0x1c0 [drm_kms_helper] process_one_work+0x184/0x380 worker_thread+0x2e/0x390 INFO: task kworker/0:2:252 blocked for more than 120 seconds. Workqueue: pm pm_runtime_work Call Trace: schedule+0x28/0x80 schedule_timeout+0x1e3/0x370 wait_for_completion+0x123/0x190 flush_work+0x142/0x1c0 nouveau_pmops_runtime_suspend+0x7e/0xd0 [nouveau] pci_pm_runtime_suspend+0x5c/0x180 vga_switcheroo_runtime_suspend+0x1e/0xa0 __rpm_callback+0xc1/0x200 rpm_callback+0x1f/0x70 rpm_suspend+0x13c/0x640 pm_runtime_work+0x6e/0x90 process_one_work+0x184/0x380 worker_thread+0x2e/0x390 Bugzilla: https://bugs.archlinux.org/task/53497 Bugzilla: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=870523 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70388#c33 Fixes: 5addcf0a5f0f ("nouveau: add runtime PM support (v0.9)") Cc: stable@vger.kernel.org # v3.12+: 27d4ee03078a: workqueue: Allow retrieval of current task's work struct Cc: stable@vger.kernel.org # v3.12+: 25c058ccaf2e: drm: Allow determining if current task is output poll worker Cc: Ben Skeggs Cc: Dave Airlie Reviewed-by: Lyude Paul Signed-off-by: Lukas Wunner Link: https://patchwork.freedesktop.org/patch/msgid/b7d2cbb609a80f59ccabfdf479b9d5907c603ea1.1518338789.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/nouveau/nouveau_connector.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) --- a/drivers/gpu/drm/nouveau/nouveau_connector.c +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c @@ -570,9 +570,15 @@ nouveau_connector_detect(struct drm_conn nv_connector->edid = NULL; } - ret = pm_runtime_get_sync(connector->dev->dev); - if (ret < 0 && ret != -EACCES) - return conn_status; + /* Outputs are only polled while runtime active, so acquiring a + * runtime PM ref here is unnecessary (and would deadlock upon + * runtime suspend because it waits for polling to finish). + */ + if (!drm_kms_helper_is_poll_worker()) { + ret = pm_runtime_get_sync(connector->dev->dev); + if (ret < 0 && ret != -EACCES) + return conn_status; + } nv_encoder = nouveau_connector_ddc_detect(connector); if (nv_encoder && (i2c = nv_encoder->i2c) != NULL) { @@ -647,8 +653,10 @@ detect_analog: out: - pm_runtime_mark_last_busy(connector->dev->dev); - pm_runtime_put_autosuspend(connector->dev->dev); + if (!drm_kms_helper_is_poll_worker()) { + pm_runtime_mark_last_busy(connector->dev->dev); + pm_runtime_put_autosuspend(connector->dev->dev); + } return conn_status; }