From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761563AbcAKRlv (ORCPT ); Mon, 11 Jan 2016 12:41:51 -0500 Received: from foss.arm.com ([217.140.101.70]:57233 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760997AbcAKRhX (ORCPT ); Mon, 11 Jan 2016 12:37:23 -0500 From: Juri Lelli To: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org, peterz@infradead.org, rjw@rjwysocki.net, viresh.kumar@linaro.org, mturquette@baylibre.com, steve.muckle@linaro.org, vincent.guittot@linaro.org, morten.rasmussen@arm.com, dietmar.eggemann@arm.com, juri.lelli@arm.com Subject: [RFC PATCH 06/19] cpufreq: always access cpufreq_policy_list while holding cpufreq_driver_lock Date: Mon, 11 Jan 2016 17:35:47 +0000 Message-Id: <1452533760-13787-7-git-send-email-juri.lelli@arm.com> X-Mailer: git-send-email 2.2.2 In-Reply-To: <1452533760-13787-1-git-send-email-juri.lelli@arm.com> References: <1452533760-13787-1-git-send-email-juri.lelli@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit highlights paths where we access cpufreq_policy_list without holding cpufreq_driver_lock; one example being the following: [ 8.245779] ------------[ cut here ]------------ [ 8.305977] WARNING: CPU: 2 PID: 1 at kernel/drivers/cpufreq/cpufreq.c:2447 cpufreq_register_driver+0xfd/0x120() [ 8.438611] Modules linked in: [ 8.493751] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.4.0-rc4+ #369 [ 8.561039] Hardware name: ARM-Versatile Express [ 8.622765] [] (unwind_backtrace) from [] (show_stack+0x11/0x14) [ 8.629651] atkbd serio0: keyboard reset failed on 1c060000.kmi [ 8.810905] [] (show_stack) from [] (dump_stack+0x55/0x78) [ 8.935122] [] (dump_stack) from [] (warn_slowpath_common+0x59/0x84) [ 9.067097] [] (warn_slowpath_common) from [] (warn_slowpath_null+0x17/0x1c) [ 9.204101] [] (warn_slowpath_null) from [] (cpufreq_register_driver+0xfd/0x120) [ 9.209603] usb 1-1.2: new high-speed USB device number 3 using isp1760 [ 9.419507] [] (cpufreq_register_driver) from [] (bL_cpufreq_register+0x49/0x98) [ 9.560548] [] (bL_cpufreq_register) from [] (platform_drv_probe+0x3b/0x6c) [ 9.573806] usb-storage 1-1.2:1.0: USB Mass Storage device detected [ 9.575468] scsi host0: usb-storage 1-1.2:1.0 [ 9.855845] [] (platform_drv_probe) from [] (driver_probe_device+0x153/0x1bc) [ 10.006137] [] (driver_probe_device) from [] (__driver_attach+0x57/0x58) [ 10.009576] atkbd serio1: keyboard reset failed on 1c070000.kmi [ 10.237057] [] (__driver_attach) from [] (bus_for_each_dev+0x2d/0x4c) [ 10.387824] [] (bus_for_each_dev) from [] (bus_add_driver+0xa3/0x14c) [ 10.539200] [] (bus_add_driver) from [] (driver_register+0x3b/0x88) [ 10.691023] [] (driver_register) from [] (do_one_initcall+0x5b/0x150) [ 10.703809] scsi 0:0:0:0: Direct-Access General USB Flash Disk 1.0 PQ: 0 ANSI: 2 [ 10.713081] sd 0:0:0:0: [sda] 7831552 512-byte logical blocks: (4.00 GB/3.73 GiB) [ 10.713973] sd 0:0:0:0: [sda] Write Protect is off [ 10.713984] sd 0:0:0:0: [sda] Mode Sense: 03 00 00 00 [ 10.730783] sd 0:0:0:0: [sda] No Caching mode page found [ 10.730814] sd 0:0:0:0: [sda] Assuming drive cache: write through [ 10.779815] sda: sda1 sda2 [ 10.823590] sd 0:0:0:0: [sda] Attached SCSI removable disk [ 11.581894] [] (do_one_initcall) from [] (kernel_init_freeable+0x18d/0x22c) [ 11.720454] [] (kernel_init_freeable) from [] (kernel_init+0xd/0xa4) [ 11.857340] [] (kernel_init) from [] (ret_from_fork+0x11/0x38) [ 11.993082] ---[ end trace 62ff5522fb3f41dd ]--- Fix this, and others, with proper locking of cpufreq_driver_lock. Cc: "Rafael J. Wysocki" Cc: Viresh Kumar Signed-off-by: Juri Lelli --- drivers/cpufreq/cpufreq.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 63d6efb..98adbc2 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1585,6 +1585,7 @@ EXPORT_SYMBOL(cpufreq_generic_suspend); void cpufreq_suspend(void) { struct cpufreq_policy *policy; + unsigned long flags; if (!cpufreq_driver) return; @@ -1594,6 +1595,7 @@ void cpufreq_suspend(void) pr_debug("%s: Suspending Governors\n", __func__); + read_lock_irqsave(&cpufreq_driver_lock, flags); for_each_active_policy(policy) { if (__cpufreq_governor(policy, CPUFREQ_GOV_STOP)) pr_err("%s: Failed to stop governor for policy: %p\n", @@ -1603,6 +1605,7 @@ void cpufreq_suspend(void) pr_err("%s: Failed to suspend driver: %p\n", __func__, policy); } + read_unlock_irqrestore(&cpufreq_driver_lock, flags); suspend: cpufreq_suspended = true; @@ -1617,6 +1620,7 @@ suspend: void cpufreq_resume(void) { struct cpufreq_policy *policy; + unsigned long flags; if (!cpufreq_driver) return; @@ -1628,6 +1632,7 @@ void cpufreq_resume(void) pr_debug("%s: Resuming Governors\n", __func__); + read_lock_irqsave(&cpufreq_driver_lock, flags); for_each_active_policy(policy) { if (cpufreq_driver->resume && cpufreq_driver->resume(policy)) pr_err("%s: Failed to resume driver: %p\n", __func__, @@ -1637,6 +1642,7 @@ void cpufreq_resume(void) pr_err("%s: Failed to start governor for policy: %p\n", __func__, policy); } + read_unlock_irqrestore(&cpufreq_driver_lock, flags); /* * schedule call cpufreq_update_policy() for first-online CPU, as that @@ -2287,7 +2293,9 @@ static int cpufreq_boost_set_sw(int state) struct cpufreq_frequency_table *freq_table; struct cpufreq_policy *policy; int ret = -EINVAL; + unsigned long flags; + read_lock_irqsave(&cpufreq_driver_lock, flags); for_each_active_policy(policy) { freq_table = cpufreq_frequency_get_table(policy->cpu); if (freq_table) { @@ -2302,6 +2310,7 @@ static int cpufreq_boost_set_sw(int state) __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS); } } + read_unlock_irqrestore(&cpufreq_driver_lock, flags); return ret; } @@ -2432,14 +2441,16 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) if (ret) goto err_boost_unreg; - lockdep_assert_held(&cpufreq_driver_lock); + read_lock_irqsave(&cpufreq_driver_lock, flags); if (!(cpufreq_driver->flags & CPUFREQ_STICKY) && list_empty(&cpufreq_policy_list)) { /* if all ->init() calls failed, unregister */ pr_debug("%s: No CPU initialized for driver %s\n", __func__, driver_data->name); + read_unlock_irqrestore(&cpufreq_driver_lock, flags); goto err_if_unreg; } + read_unlock_irqrestore(&cpufreq_driver_lock, flags); register_hotcpu_notifier(&cpufreq_cpu_notifier); pr_debug("driver %s up and running\n", driver_data->name); -- 2.2.2