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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-04-02 01:25:24 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-04-02 01:25:24 +0200
commit0f703069296664eb7c649c837cc8bb936c3ef07f (patch)
tree93952cad59fcb7b2736ab686fb0cf0be83559746
parentda259465d7526804b21d274281fb4d60b4216c82 (diff)
downloadvexpress-lsk-0f703069296664eb7c649c837cc8bb936c3ef07f.tar.gz
PM / QoS: Avoid possible deadlock related to sysfs access
Commit b81ea1b (PM / QoS: Fix concurrency issues and memory leaks in device PM QoS) put calls to pm_qos_sysfs_add_latency(), pm_qos_sysfs_add_flags(), pm_qos_sysfs_remove_latency(), and pm_qos_sysfs_remove_flags() under dev_pm_qos_mtx, which was a mistake, because it may lead to deadlocks in some situations. For example, if pm_qos_remote_wakeup_store() is run in parallel with dev_pm_qos_constraints_destroy(), they may deadlock in the following way: ====================================================== [ INFO: possible circular locking dependency detected ] 3.9.0-rc4-next-20130328-sasha-00014-g91a3267 #319 Tainted: G W ------------------------------------------------------- trinity-child6/12371 is trying to acquire lock: (s_active#54){++++.+}, at: [<ffffffff81301631>] sysfs_addrm_finish+0x31/0x60 but task is already holding lock: (dev_pm_qos_mtx){+.+.+.}, at: [<ffffffff81f07cc3>] dev_pm_qos_constraints_destroy+0x23/0x250 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (dev_pm_qos_mtx){+.+.+.}: [<ffffffff811811da>] lock_acquire+0x1aa/0x240 [<ffffffff83dab809>] __mutex_lock_common+0x59/0x5e0 [<ffffffff83dabebf>] mutex_lock_nested+0x3f/0x50 [<ffffffff81f07f2f>] dev_pm_qos_update_flags+0x3f/0xc0 [<ffffffff81f05f4f>] pm_qos_remote_wakeup_store+0x3f/0x70 [<ffffffff81efbb43>] dev_attr_store+0x13/0x20 [<ffffffff812ffdaa>] sysfs_write_file+0xfa/0x150 [<ffffffff8127f2c1>] __kernel_write+0x81/0x150 [<ffffffff812afc2d>] write_pipe_buf+0x4d/0x80 [<ffffffff812af57c>] splice_from_pipe_feed+0x7c/0x120 [<ffffffff812afa25>] __splice_from_pipe+0x45/0x80 [<ffffffff812b14fc>] splice_from_pipe+0x4c/0x70 [<ffffffff812b1538>] default_file_splice_write+0x18/0x30 [<ffffffff812afae3>] do_splice_from+0x83/0xb0 [<ffffffff812afb2e>] direct_splice_actor+0x1e/0x20 [<ffffffff812b0277>] splice_direct_to_actor+0xe7/0x200 [<ffffffff812b15bc>] do_splice_direct+0x4c/0x70 [<ffffffff8127eda9>] do_sendfile+0x169/0x300 [<ffffffff8127ff94>] SyS_sendfile64+0x64/0xb0 [<ffffffff83db7d18>] tracesys+0xe1/0xe6 -> #0 (s_active#54){++++.+}: [<ffffffff811800cf>] __lock_acquire+0x15bf/0x1e50 [<ffffffff811811da>] lock_acquire+0x1aa/0x240 [<ffffffff81300aa2>] sysfs_deactivate+0x122/0x1a0 [<ffffffff81301631>] sysfs_addrm_finish+0x31/0x60 [<ffffffff812ff77f>] sysfs_hash_and_remove+0x7f/0xb0 [<ffffffff813035a1>] sysfs_unmerge_group+0x51/0x70 [<ffffffff81f068f4>] pm_qos_sysfs_remove_flags+0x14/0x20 [<ffffffff81f07490>] __dev_pm_qos_hide_flags+0x30/0x70 [<ffffffff81f07cd5>] dev_pm_qos_constraints_destroy+0x35/0x250 [<ffffffff81f06931>] dpm_sysfs_remove+0x11/0x50 [<ffffffff81efcf6f>] device_del+0x3f/0x1b0 [<ffffffff81efd128>] device_unregister+0x48/0x60 [<ffffffff82d4083c>] usb_hub_remove_port_device+0x1c/0x20 [<ffffffff82d2a9cd>] hub_disconnect+0xdd/0x160 [<ffffffff82d36ab7>] usb_unbind_interface+0x67/0x170 [<ffffffff81f001a7>] __device_release_driver+0x87/0xe0 [<ffffffff81f00559>] device_release_driver+0x29/0x40 [<ffffffff81effc58>] bus_remove_device+0x148/0x160 [<ffffffff81efd07f>] device_del+0x14f/0x1b0 [<ffffffff82d344f9>] usb_disable_device+0xf9/0x280 [<ffffffff82d34ff8>] usb_set_configuration+0x268/0x840 [<ffffffff82d3a7fc>] usb_remove_store+0x4c/0x80 [<ffffffff81efbb43>] dev_attr_store+0x13/0x20 [<ffffffff812ffdaa>] sysfs_write_file+0xfa/0x150 [<ffffffff8127f71d>] do_loop_readv_writev+0x4d/0x90 [<ffffffff8127f999>] do_readv_writev+0xf9/0x1e0 [<ffffffff8127faba>] vfs_writev+0x3a/0x60 [<ffffffff8127fc60>] SyS_writev+0x50/0xd0 [<ffffffff83db7d18>] tracesys+0xe1/0xe6 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(dev_pm_qos_mtx); lock(s_active#54); lock(dev_pm_qos_mtx); lock(s_active#54); *** DEADLOCK *** To avoid that, remove the calls to functions mentioned above from under dev_pm_qos_mtx and introduce a separate lock to prevent races between functions that add or remove device PM QoS sysfs attributes from happening. Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-rw-r--r--drivers/base/power/qos.c60
1 files changed, 47 insertions, 13 deletions
diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
index 5f74587ef25..71671c42ef4 100644
--- a/drivers/base/power/qos.c
+++ b/drivers/base/power/qos.c
@@ -46,6 +46,7 @@
#include "power.h"
static DEFINE_MUTEX(dev_pm_qos_mtx);
+static DEFINE_MUTEX(dev_pm_qos_sysfs_mtx);
static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers);
@@ -216,12 +217,17 @@ void dev_pm_qos_constraints_destroy(struct device *dev)
struct pm_qos_constraints *c;
struct pm_qos_flags *f;
- mutex_lock(&dev_pm_qos_mtx);
+ mutex_lock(&dev_pm_qos_sysfs_mtx);
/*
* If the device's PM QoS resume latency limit or PM QoS flags have been
* exposed to user space, they have to be hidden at this point.
*/
+ pm_qos_sysfs_remove_latency(dev);
+ pm_qos_sysfs_remove_flags(dev);
+
+ mutex_lock(&dev_pm_qos_mtx);
+
__dev_pm_qos_hide_latency_limit(dev);
__dev_pm_qos_hide_flags(dev);
@@ -254,6 +260,8 @@ void dev_pm_qos_constraints_destroy(struct device *dev)
out:
mutex_unlock(&dev_pm_qos_mtx);
+
+ mutex_unlock(&dev_pm_qos_sysfs_mtx);
}
/**
@@ -558,6 +566,14 @@ static void __dev_pm_qos_drop_user_request(struct device *dev,
kfree(req);
}
+static void dev_pm_qos_drop_user_request(struct device *dev,
+ enum dev_pm_qos_req_type type)
+{
+ mutex_lock(&dev_pm_qos_mtx);
+ __dev_pm_qos_drop_user_request(dev, type);
+ mutex_unlock(&dev_pm_qos_mtx);
+}
+
/**
* dev_pm_qos_expose_latency_limit - Expose PM QoS latency limit to user space.
* @dev: Device whose PM QoS latency limit is to be exposed to user space.
@@ -581,6 +597,8 @@ int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value)
return ret;
}
+ mutex_lock(&dev_pm_qos_sysfs_mtx);
+
mutex_lock(&dev_pm_qos_mtx);
if (IS_ERR_OR_NULL(dev->power.qos))
@@ -591,26 +609,27 @@ int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value)
if (ret < 0) {
__dev_pm_qos_remove_request(req);
kfree(req);
+ mutex_unlock(&dev_pm_qos_mtx);
goto out;
}
-
dev->power.qos->latency_req = req;
+
+ mutex_unlock(&dev_pm_qos_mtx);
+
ret = pm_qos_sysfs_add_latency(dev);
if (ret)
- __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
+ dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
out:
- mutex_unlock(&dev_pm_qos_mtx);
+ mutex_unlock(&dev_pm_qos_sysfs_mtx);
return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_qos_expose_latency_limit);
static void __dev_pm_qos_hide_latency_limit(struct device *dev)
{
- if (!IS_ERR_OR_NULL(dev->power.qos) && dev->power.qos->latency_req) {
- pm_qos_sysfs_remove_latency(dev);
+ if (!IS_ERR_OR_NULL(dev->power.qos) && dev->power.qos->latency_req)
__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
- }
}
/**
@@ -619,9 +638,15 @@ static void __dev_pm_qos_hide_latency_limit(struct device *dev)
*/
void dev_pm_qos_hide_latency_limit(struct device *dev)
{
+ mutex_lock(&dev_pm_qos_sysfs_mtx);
+
+ pm_qos_sysfs_remove_latency(dev);
+
mutex_lock(&dev_pm_qos_mtx);
__dev_pm_qos_hide_latency_limit(dev);
mutex_unlock(&dev_pm_qos_mtx);
+
+ mutex_unlock(&dev_pm_qos_sysfs_mtx);
}
EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_limit);
@@ -649,6 +674,8 @@ int dev_pm_qos_expose_flags(struct device *dev, s32 val)
}
pm_runtime_get_sync(dev);
+ mutex_lock(&dev_pm_qos_sysfs_mtx);
+
mutex_lock(&dev_pm_qos_mtx);
if (IS_ERR_OR_NULL(dev->power.qos))
@@ -659,16 +686,19 @@ int dev_pm_qos_expose_flags(struct device *dev, s32 val)
if (ret < 0) {
__dev_pm_qos_remove_request(req);
kfree(req);
+ mutex_unlock(&dev_pm_qos_mtx);
goto out;
}
-
dev->power.qos->flags_req = req;
+
+ mutex_unlock(&dev_pm_qos_mtx);
+
ret = pm_qos_sysfs_add_flags(dev);
if (ret)
- __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
+ dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
out:
- mutex_unlock(&dev_pm_qos_mtx);
+ mutex_unlock(&dev_pm_qos_sysfs_mtx);
pm_runtime_put(dev);
return ret;
}
@@ -676,10 +706,8 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_expose_flags);
static void __dev_pm_qos_hide_flags(struct device *dev)
{
- if (!IS_ERR_OR_NULL(dev->power.qos) && dev->power.qos->flags_req) {
- pm_qos_sysfs_remove_flags(dev);
+ if (!IS_ERR_OR_NULL(dev->power.qos) && dev->power.qos->flags_req)
__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
- }
}
/**
@@ -689,9 +717,15 @@ static void __dev_pm_qos_hide_flags(struct device *dev)
void dev_pm_qos_hide_flags(struct device *dev)
{
pm_runtime_get_sync(dev);
+ mutex_lock(&dev_pm_qos_sysfs_mtx);
+
+ pm_qos_sysfs_remove_flags(dev);
+
mutex_lock(&dev_pm_qos_mtx);
__dev_pm_qos_hide_flags(dev);
mutex_unlock(&dev_pm_qos_mtx);
+
+ mutex_unlock(&dev_pm_qos_sysfs_mtx);
pm_runtime_put(dev);
}
EXPORT_SYMBOL_GPL(dev_pm_qos_hide_flags);