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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 367D4C433DB for ; Mon, 25 Jan 2021 23:50:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3D25229EF for ; Mon, 25 Jan 2021 23:50:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732769AbhAYXuE (ORCPT ); Mon, 25 Jan 2021 18:50:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53644 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732561AbhAYXto (ORCPT ); Mon, 25 Jan 2021 18:49:44 -0500 Received: from mail-pg1-x52e.google.com (mail-pg1-x52e.google.com [IPv6:2607:f8b0:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32E6AC061756 for ; Mon, 25 Jan 2021 15:49:04 -0800 (PST) Received: by mail-pg1-x52e.google.com with SMTP id n10so10024794pgl.10 for ; Mon, 25 Jan 2021 15:49:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=cuvqgCacX4Pb/J8emd8ASYQj+aaRXfkyo5/tJUTXC18=; b=LvIzG2oiZ4fahhXWU/Hl16GJoovvy1FodGhzRZkhCPyPmFR19R6r1WEoZrBUzLtIMM QnTuqHFjlL4l5yPZWzb/BVOd4vaakKa63tFoLObC5jY+g4UzkqDJBZVBH9En3d5sFUYn fdo0AQZ6EtqeWqTx4+L0QXmfvUYGKyCPwHLvI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=cuvqgCacX4Pb/J8emd8ASYQj+aaRXfkyo5/tJUTXC18=; b=RUVQLcZ6h5KBiPNhtYmwjHFoD5SJ30/y5CxzWyIRuB8SkoQsGW9AUwJzpmTg5y2c/b 7ai8bbnznYZ5KQg6ozIWp+g3kufbrRQJQGhuDnkDhbveIwuqwHK+rLOWly2yjYtztGfB SXMApqnspXbyD3b3Rx9Gtw0AC15tDBBAUK+0aseRKrNBi6tcEyUzmWV8cxXeOtvMM4NR np7rGYlxmsdAj2eHdgCAYg/oPibf+FdcK4eflewrjCKkCUvsk9NVck96Az92k7hz3xzy AhF5KMKgp66cnVWqwzO03NPPwNrvxcmWwCxjNFiDJdAQdwEsBY05rGiOKlY0DYhFtGk9 lywA== X-Gm-Message-State: AOAM532MKCitjaAvW+b7m45JRqG5fKP406nti+ZuxCWzaAdcBd8XmcX1 L6tCidbLEr3W3Um0AQOx8Mp2gw== X-Google-Smtp-Source: ABdhPJzO6lwEiB9rHDjl2mcIoIHLun1mZSg9GDhVd7nQPhP25HL0bRXA4RqsiCg8fZUxTOaI377yHw== X-Received: by 2002:a62:9248:0:b029:1ae:8b24:34c8 with SMTP id o69-20020a6292480000b02901ae8b2434c8mr2565829pfd.67.1611618543734; Mon, 25 Jan 2021 15:49:03 -0800 (PST) Received: from smtp.gmail.com ([2620:15c:202:201:1066:b437:97cd:2278]) by smtp.gmail.com with ESMTPSA id i1sm18747306pfb.54.2021.01.25.15.49.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jan 2021 15:49:03 -0800 (PST) From: Stephen Boyd To: Rob Clark Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Krishna Manikandan Subject: [PATCH] drm/msm/kms: Make a lock_class_key for each crtc mutex Date: Mon, 25 Jan 2021 15:49:01 -0800 Message-Id: <20210125234901.2730699-1-swboyd@chromium.org> X-Mailer: git-send-email 2.30.0.280.ga3ce27912f-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Lockdep complains about an AA deadlock when rebooting the device. ============================================ WARNING: possible recursive locking detected 5.4.91 #1 Not tainted -------------------------------------------- reboot/5213 is trying to acquire lock: ffffff80d13391b0 (&kms->commit_lock[i]){+.+.}, at: lock_crtcs+0x60/0xa4 but task is already holding lock: ffffff80d1339110 (&kms->commit_lock[i]){+.+.}, at: lock_crtcs+0x60/0xa4 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&kms->commit_lock[i]); lock(&kms->commit_lock[i]); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by reboot/5213: __arm64_sys_reboot+0x148/0x2a0 device_shutdown+0x10c/0x2c4 drm_atomic_helper_shutdown+0x48/0xfc modeset_lock+0x120/0x24c lock_crtcs+0x60/0xa4 stack backtrace: CPU: 4 PID: 5213 Comm: reboot Not tainted 5.4.91 #1 Hardware name: Google Pompom (rev1) with LTE (DT) Call trace: dump_backtrace+0x0/0x1dc show_stack+0x24/0x30 dump_stack+0xfc/0x1a8 __lock_acquire+0xcd0/0x22b8 lock_acquire+0x1ec/0x240 __mutex_lock_common+0xe0/0xc84 mutex_lock_nested+0x48/0x58 lock_crtcs+0x60/0xa4 msm_atomic_commit_tail+0x348/0x570 commit_tail+0xdc/0x178 drm_atomic_helper_commit+0x160/0x168 drm_atomic_commit+0x68/0x80 This is because lockdep thinks all the locks taken in lock_crtcs() are the same lock, when they actually aren't. That's because we call mutex_init() in msm_kms_init() and that assigns on static key for every lock initialized in this loop. Let's allocate a dynamic number of lock_class_keys and assign them to each lock so that lockdep can figure out an AA deadlock isn't possible here. Fixes: b3d91800d9ac ("drm/msm: Fix race condition in msm driver with async layer updates") Cc: Krishna Manikandan Signed-off-by: Stephen Boyd --- drivers/gpu/drm/msm/msm_kms.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/msm/msm_kms.h b/drivers/gpu/drm/msm/msm_kms.h index d8151a89e163..4735251a394d 100644 --- a/drivers/gpu/drm/msm/msm_kms.h +++ b/drivers/gpu/drm/msm/msm_kms.h @@ -157,6 +157,7 @@ struct msm_kms { * from the crtc's pending_timer close to end of the frame: */ struct mutex commit_lock[MAX_CRTCS]; + struct lock_class_key commit_lock_keys[MAX_CRTCS]; unsigned pending_crtc_mask; struct msm_pending_timer pending_timers[MAX_CRTCS]; }; @@ -166,8 +167,11 @@ static inline int msm_kms_init(struct msm_kms *kms, { unsigned i, ret; - for (i = 0; i < ARRAY_SIZE(kms->commit_lock); i++) - mutex_init(&kms->commit_lock[i]); + for (i = 0; i < ARRAY_SIZE(kms->commit_lock); i++) { + lockdep_register_key(&kms->commit_lock_keys[i]); + __mutex_init(&kms->commit_lock[i], "&kms->commit_lock[i]", + &kms->commit_lock_keys[i]); + } kms->funcs = funcs; base-commit: 19c329f6808995b142b3966301f217c831e7cf31 -- https://chromeos.dev