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=-6.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS 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 156A6C43381 for ; Sun, 17 Feb 2019 16:27:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B28382192C for ; Sun, 17 Feb 2019 16:27:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="vBvMtoVd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726087AbfBQQ1l (ORCPT ); Sun, 17 Feb 2019 11:27:41 -0500 Received: from pandora.armlinux.org.uk ([78.32.30.218]:39652 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725801AbfBQQ1l (ORCPT ); Sun, 17 Feb 2019 11:27:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Date:Sender:Message-Id:Content-Type: Content-Transfer-Encoding:MIME-Version:Subject:Cc:To:From:Reply-To:Content-ID :Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To: Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=jcBtIrU9Z9mDTzksNlWTGLrbqeXd8V1A/NHKVCK6yH8=; b=vBvMtoVd16arJFMre2PLyo/tiI 8i0F5xOmWTJMrGJYqG+6H0bPFsi0W8Fquej8EFlTPYsYNps5lqNKU8u3CrrzGwIEVbDv7IdddgT9/ g51s7K8i+QLzctPmhofx2Y5bT2ywAs1whku2o0pqCsirLJ2s6EbHy7rzq3qQpR+cqm8CXEOqO9rCE IsTiKYzY3E3SOd+vEXdx9SFM8Va8yOiqG7oj/wLHRB6qa2A9g23MIzme+73uotIgJ0Sdvciu0l1uE 1+U7sIAuE4FvBfCWKBMV+v0lN5eWBatCBxDp8euJiGQREiOVnke0Fqw9qSLolEOtpuDRYKeMUMcqr l3WyIKWA==; Received: from e0022681537dd.dyn.armlinux.org.uk ([2002:4e20:1eda:1:222:68ff:fe15:37dd]:56678 helo=rmk-PC.armlinux.org.uk) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.90_1) (envelope-from ) id 1gvPHx-0001HQ-FI; Sun, 17 Feb 2019 16:27:33 +0000 Received: from rmk by rmk-PC.armlinux.org.uk with local (Exim 4.82_1-5b7a7c0-XX) (envelope-from ) id 1gvPHw-0008OD-To; Sun, 17 Feb 2019 16:27:32 +0000 From: Russell King To: Andrew Lunn , Florian Fainelli , Vivien Didelot Cc: Heiner Kallweit , "David S. Miller" , netdev@vger.kernel.org Subject: [PATCH net] net: dsa: fix lockdep warning MIME-Version: 1.0 Content-Disposition: inline Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="utf-8" Message-Id: Date: Sun, 17 Feb 2019 16:27:32 +0000 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org ====================================================== WARNING: possible circular locking dependency detected 4.20.0+ #302 Not tainted ------------------------------------------------------ systemd-udevd/160 is trying to acquire lock: edea6080 (&chip->reg_lock){+.+.}, at: __setup_irq+0x640/0x704 but task is already holding lock: edff0340 (&desc->request_mutex){+.+.}, at: __setup_irq+0xa0/0x704 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&desc->request_mutex){+.+.}: mutex_lock_nested+0x1c/0x24 __setup_irq+0xa0/0x704 request_threaded_irq+0xd0/0x150 mv88e6xxx_probe+0x41c/0x694 [mv88e6xxx] mdio_probe+0x2c/0x54 really_probe+0x200/0x2c4 driver_probe_device+0x5c/0x174 __driver_attach+0xd8/0xdc bus_for_each_dev+0x58/0x7c bus_add_driver+0xe4/0x1f0 driver_register+0x7c/0x110 mdio_driver_register+0x24/0x58 do_one_initcall+0x74/0x2e8 do_init_module+0x60/0x1d0 load_module+0x1968/0x1ff4 sys_finit_module+0x8c/0x98 ret_fast_syscall+0x0/0x28 0xbedf2ae8 -> #0 (&chip->reg_lock){+.+.}: __mutex_lock+0x50/0x8b8 mutex_lock_nested+0x1c/0x24 __setup_irq+0x640/0x704 request_threaded_irq+0xd0/0x150 mv88e6xxx_g2_irq_setup+0xcc/0x1b4 [mv88e6xxx] mv88e6xxx_probe+0x44c/0x694 [mv88e6xxx] mdio_probe+0x2c/0x54 really_probe+0x200/0x2c4 driver_probe_device+0x5c/0x174 __driver_attach+0xd8/0xdc bus_for_each_dev+0x58/0x7c bus_add_driver+0xe4/0x1f0 driver_register+0x7c/0x110 mdio_driver_register+0x24/0x58 do_one_initcall+0x74/0x2e8 do_init_module+0x60/0x1d0 load_module+0x1968/0x1ff4 sys_finit_module+0x8c/0x98 ret_fast_syscall+0x0/0x28 0xbedf2ae8 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&desc->request_mutex); lock(&chip->reg_lock); lock(&desc->request_mutex); lock(&chip->reg_lock); *** DEADLOCK *** 2 locks held by systemd-udevd/160: #0: ee040868 (&dev->mutex){....}, at: __driver_attach+0x70/0xdc #1: edff0340 (&desc->request_mutex){+.+.}, at: __setup_irq+0xa0/0x704 stack backtrace: CPU: 1 PID: 160 Comm: systemd-udevd Not tainted 4.20.0+ #302 Hardware name: Marvell Armada 380/385 (Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0x9c/0xd4) [] (dump_stack) from [] (print_circular_bug+0x284/0x2d8) [] (print_circular_bug) from [] (__lock_acquire+0x15d4/0x19b8) [] (__lock_acquire) from [] (lock_acquire+0xc4/0x1dc) [] (lock_acquire) from [] (__mutex_lock+0x50/0x8b8) [] (__mutex_lock) from [] (mutex_lock_nested+0x1c/0x24) [] (mutex_lock_nested) from [] (__setup_irq+0x640/0x704) [] (__setup_irq) from [] (request_threaded_irq+0xd0/0x150) [] (request_threaded_irq) from [] (mv88e6xxx_g2_irq_setup+0xcc/0x1b4 [mv88e6xxx]) [] (mv88e6xxx_g2_irq_setup [mv88e6xxx]) from [] (mv88e6xxx_probe+0x44c/0x694 [mv88e6xxx]) [] (mv88e6xxx_probe [mv88e6xxx]) from [] (mdio_probe+0x2c/0x54) [] (mdio_probe) from [] (really_probe+0x200/0x2c4) [] (really_probe) from [] (driver_probe_device+0x5c/0x174) [] (driver_probe_device) from [] (__driver_attach+0xd8/0xdc) [] (__driver_attach) from [] (bus_for_each_dev+0x58/0x7c) [] (bus_for_each_dev) from [] (bus_add_driver+0xe4/0x1f0) [] (bus_add_driver) from [] (driver_register+0x7c/0x110) [] (driver_register) from [] (mdio_driver_register+0x24/0x58) [] (mdio_driver_register) from [] (do_one_initcall+0x74/0x2e8) [] (do_one_initcall) from [] (do_init_module+0x60/0x1d0) [] (do_init_module) from [] (load_module+0x1968/0x1ff4) mvneta f1034000.ethernet eth2: requesting inband/2500base-x, 00200,0000a440 [] (load_module) from [] (sys_finit_module+0x8c/0x98) [] (sys_finit_module) from [] (ret_fast_syscall+0x0/0x28) Exception stack(0xedfe5fa8 to 0xedfe5ff0) 5fa0: 00020000 00000000 0000000b b6f2a4b5 00000000 00b8fc70 5fc0: 00020000 00000000 00000000 0000017b 00b995a0 00020000 00000000 00b8fc70 5fe0: bedf2af8 bedf2ae8 b6f242ac b6e83d70 This is caused by the locking order inversion in mv88e6xxx_probe: mutex_lock(&chip->reg_lock); if (chip->irq > 0) err = mv88e6xxx_g1_irq_setup(chip); else err = mv88e6xxx_irq_poll_setup(chip); mutex_unlock(&chip->reg_lock); Here, we take chip->reg_lock, and then call into mv88e6xxx_g1_irq_setup() which then calls request_threaded_irq(), taking the request_mutex. However, when we request the g2 interrupt, we call request_threaded_irq() again, which takes the request_mutex, which then goes on to call chip_bus_lock(). This comes through to mv88e6xxx_g1_irq_bus_lock, which then tries to grab chip->reg_lock. This results in the two locks being taken together in differing orders, provoking lockdep to warn. Move the mutex_lock()/unlock() for reg_lock inside mv88e6xxx_g1_irq_free_common() and mv88e6xxx_g1_irq_setup_common(), where we actually access registers, thereby avoiding holding it while calling request_threaded_irq() or setting up the delayed work. Signed-off-by: Russell King --- drivers/net/dsa/mv88e6xxx/chip.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c index 24fb6a685039..801442195a04 100644 --- a/drivers/net/dsa/mv88e6xxx/chip.c +++ b/drivers/net/dsa/mv88e6xxx/chip.c @@ -349,9 +349,11 @@ static void mv88e6xxx_g1_irq_free_common(struct mv88e6xxx_chip *chip) int irq, virq; u16 mask; + mutex_lock(&chip->reg_lock); mv88e6xxx_g1_read(chip, MV88E6XXX_G1_CTL1, &mask); mask &= ~GENMASK(chip->g1_irq.nirqs, 0); mv88e6xxx_g1_write(chip, MV88E6XXX_G1_CTL1, mask); + mutex_unlock(&chip->reg_lock); for (irq = 0; irq < chip->g1_irq.nirqs; irq++) { virq = irq_find_mapping(chip->g1_irq.domain, irq); @@ -369,9 +371,7 @@ static void mv88e6xxx_g1_irq_free(struct mv88e6xxx_chip *chip) */ free_irq(chip->irq, chip); - mutex_lock(&chip->reg_lock); mv88e6xxx_g1_irq_free_common(chip); - mutex_unlock(&chip->reg_lock); } static int mv88e6xxx_g1_irq_setup_common(struct mv88e6xxx_chip *chip) @@ -392,6 +392,7 @@ static int mv88e6xxx_g1_irq_setup_common(struct mv88e6xxx_chip *chip) chip->g1_irq.chip = mv88e6xxx_g1_irq_chip; chip->g1_irq.masked = ~0; + mutex_lock(&chip->reg_lock); err = mv88e6xxx_g1_read(chip, MV88E6XXX_G1_CTL1, &mask); if (err) goto out_mapping; @@ -406,6 +407,7 @@ static int mv88e6xxx_g1_irq_setup_common(struct mv88e6xxx_chip *chip) err = mv88e6xxx_g1_read(chip, MV88E6XXX_G1_STS, ®); if (err) goto out_disable; + mutex_unlock(&chip->reg_lock); return 0; @@ -414,6 +416,7 @@ static int mv88e6xxx_g1_irq_setup_common(struct mv88e6xxx_chip *chip) mv88e6xxx_g1_write(chip, MV88E6XXX_G1_CTL1, mask); out_mapping: + mutex_unlock(&chip->reg_lock); for (irq = 0; irq < 16; irq++) { virq = irq_find_mapping(chip->g1_irq.domain, irq); irq_dispose_mapping(virq); @@ -479,9 +482,7 @@ static void mv88e6xxx_irq_poll_free(struct mv88e6xxx_chip *chip) kthread_cancel_delayed_work_sync(&chip->irq_poll_work); kthread_destroy_worker(chip->kworker); - mutex_lock(&chip->reg_lock); mv88e6xxx_g1_irq_free_common(chip); - mutex_unlock(&chip->reg_lock); } int mv88e6xxx_wait(struct mv88e6xxx_chip *chip, int addr, int reg, u16 mask) @@ -4718,12 +4719,10 @@ static int mv88e6xxx_probe(struct mdio_device *mdiodev) * the PHYs will link their interrupts to these interrupt * controllers */ - mutex_lock(&chip->reg_lock); if (chip->irq > 0) err = mv88e6xxx_g1_irq_setup(chip); else err = mv88e6xxx_irq_poll_setup(chip); - mutex_unlock(&chip->reg_lock); if (err) goto out; -- 2.7.4