From d6b0c58048d2c8c6f4955c37f670125b2792cd14 Mon Sep 17 00:00:00 2001 From: Dmitry Torokhov Date: Sat, 23 Feb 2013 13:11:14 -0800 Subject: devres: allow adding custom actions to the stack Sometimes drivers need to execute one-off actions in their error handling or device teardown paths. An example would be toggling a GPIO line to reset the controlled device into predefined state. To allow performing such actions when using managed resources let's allow adding them to stack/group of devres resources. Acked-by: Tejun Heo Acked-by: Greg Kroah-Hartman Signed-off-by: Dmitry Torokhov --- include/linux/device.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index 86ef6ab553b1..854b247bf5f9 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -567,6 +567,10 @@ extern void devm_kfree(struct device *dev, void *p); void __iomem *devm_request_and_ioremap(struct device *dev, struct resource *res); +/* allows to add/remove a custom action to devres stack */ +int devm_add_action(struct device *dev, void (*action)(void *), void *data); +void devm_remove_action(struct device *dev, void (*action)(void *), void *data); + struct device_dma_parameters { /* * a low level driver may set these to teach IOMMU code about -- cgit v1.2.3 From d73ce004225a7b2ed75f4340bb63721d55552265 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 12 Mar 2013 11:30:05 -0700 Subject: driver/base: implement subsys_virtual_register() Kay tells me the most appropriate place to expose workqueues to userland would be /sys/devices/virtual/workqueues/WQ_NAME which is symlinked to /sys/bus/workqueue/devices/WQ_NAME and that we're lacking a way to do that outside of driver core as virtual_device_parent() isn't exported and there's no inteface to conveniently create a virtual subsystem. This patch implements subsys_virtual_register() by factoring out subsys_register() from subsys_system_register() and using it with virtual_device_parent() as the origin directory. It's identical to subsys_system_register() other than the origin directory but we aren't gonna restrict the device names which should be used under it. This will be used to expose workqueue attributes to userland. Signed-off-by: Tejun Heo Acked-by: Greg Kroah-Hartman Cc: Kay Sievers --- include/linux/device.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index 9d6464ea99c6..ee10d4e7be1a 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -302,6 +302,8 @@ void subsys_interface_unregister(struct subsys_interface *sif); int subsys_system_register(struct bus_type *subsys, const struct attribute_group **groups); +int subsys_virtual_register(struct bus_type *subsys, + const struct attribute_group **groups); /** * struct class - device classes -- cgit v1.2.3 From be871b7e54711479d3b9d3617d49898770830db2 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Tue, 12 Mar 2013 17:21:19 +0100 Subject: device: separate all subsys mutexes ca22e56d (driver-core: implement 'sysdev' functionality for regular devices and buses) has introduced bus_register macro with a static key to distinguish different subsys mutex classes. This however doesn't work for different subsys which use a common registering function. One example is subsys_system_register (and mce_device and cpu_device). In the end this leads to the following lockdep splat: [ 207.271924] ====================================================== [ 207.271932] [ INFO: possible circular locking dependency detected ] [ 207.271942] 3.9.0-rc1-0.7-default+ #34 Not tainted [ 207.271948] ------------------------------------------------------- [ 207.271957] bash/10493 is trying to acquire lock: [ 207.271963] (subsys mutex){+.+.+.}, at: [] bus_remove_device+0x37/0x1c0 [ 207.271987] [ 207.271987] but task is already holding lock: [ 207.271995] (cpu_hotplug.lock){+.+.+.}, at: [] cpu_hotplug_begin+0x2f/0x60 [ 207.272012] [ 207.272012] which lock already depends on the new lock. [ 207.272012] [ 207.272023] [ 207.272023] the existing dependency chain (in reverse order) is: [ 207.272033] [ 207.272033] -> #4 (cpu_hotplug.lock){+.+.+.}: [ 207.272044] [] lock_acquire+0xe9/0x120 [ 207.272056] [] mutex_lock_nested+0x37/0x360 [ 207.272069] [] get_online_cpus+0x29/0x40 [ 207.272082] [] drain_all_stock+0x30/0x150 [ 207.272094] [] mem_cgroup_reclaim+0xaa/0xe0 [ 207.272104] [] __mem_cgroup_try_charge+0x51e/0xcf0 [ 207.272114] [] mem_cgroup_charge_common+0x36/0x60 [ 207.272125] [] mem_cgroup_newpage_charge+0x2a/0x30 [ 207.272135] [] do_wp_page+0x231/0x830 [ 207.272147] [] handle_pte_fault+0x19e/0x8d0 [ 207.272157] [] handle_mm_fault+0x158/0x1e0 [ 207.272166] [] do_page_fault+0x2a3/0x4e0 [ 207.272178] [] page_fault+0x28/0x30 [ 207.272189] [ 207.272189] -> #3 (&mm->mmap_sem){++++++}: [ 207.272199] [] lock_acquire+0xe9/0x120 [ 207.272208] [] might_fault+0x6d/0x90 [ 207.272218] [] filldir64+0xb3/0x120 [ 207.272229] [] call_filldir+0x89/0x130 [ext3] [ 207.272248] [] ext3_readdir+0x6b7/0x7e0 [ext3] [ 207.272263] [] vfs_readdir+0xa9/0xc0 [ 207.272273] [] sys_getdents64+0x9b/0x110 [ 207.272284] [] system_call_fastpath+0x16/0x1b [ 207.272296] [ 207.272296] -> #2 (&type->i_mutex_dir_key#3){+.+.+.}: [ 207.272309] [] lock_acquire+0xe9/0x120 [ 207.272319] [] mutex_lock_nested+0x37/0x360 [ 207.272329] [] link_path_walk+0x6f4/0x9a0 [ 207.272339] [] path_openat+0xba/0x470 [ 207.272349] [] do_filp_open+0x48/0xa0 [ 207.272358] [] file_open_name+0xdc/0x110 [ 207.272369] [] filp_open+0x35/0x40 [ 207.272378] [] _request_firmware+0x52e/0xb20 [ 207.272389] [] request_firmware+0x16/0x20 [ 207.272399] [] request_microcode_fw+0x61/0xd0 [microcode] [ 207.272416] [] microcode_init_cpu+0x104/0x150 [microcode] [ 207.272431] [] mc_device_add+0x7c/0xb0 [microcode] [ 207.272444] [] subsys_interface_register+0xc9/0x100 [ 207.272457] [] 0xffffffffa04fc0f4 [ 207.272472] [] do_one_initcall+0x42/0x180 [ 207.272485] [] load_module+0x19df/0x1b70 [ 207.272499] [] sys_init_module+0xe6/0x130 [ 207.272511] [] system_call_fastpath+0x16/0x1b [ 207.272523] [ 207.272523] -> #1 (umhelper_sem){++++.+}: [ 207.272537] [] lock_acquire+0xe9/0x120 [ 207.272548] [] down_read+0x34/0x50 [ 207.272559] [] usermodehelper_read_trylock+0x4f/0x100 [ 207.272575] [] _request_firmware+0x59d/0xb20 [ 207.272587] [] request_firmware+0x16/0x20 [ 207.272599] [] request_microcode_fw+0x61/0xd0 [microcode] [ 207.272613] [] microcode_init_cpu+0x104/0x150 [microcode] [ 207.272627] [] mc_device_add+0x7c/0xb0 [microcode] [ 207.272641] [] subsys_interface_register+0xc9/0x100 [ 207.272654] [] 0xffffffffa04fc0f4 [ 207.272666] [] do_one_initcall+0x42/0x180 [ 207.272678] [] load_module+0x19df/0x1b70 [ 207.272690] [] sys_init_module+0xe6/0x130 [ 207.272702] [] system_call_fastpath+0x16/0x1b [ 207.272715] [ 207.272715] -> #0 (subsys mutex){+.+.+.}: [ 207.272729] [] __lock_acquire+0x13b2/0x15f0 [ 207.272740] [] lock_acquire+0xe9/0x120 [ 207.272751] [] mutex_lock_nested+0x37/0x360 [ 207.272763] [] bus_remove_device+0x37/0x1c0 [ 207.272775] [] device_del+0x134/0x1f0 [ 207.272786] [] device_unregister+0x22/0x60 [ 207.272798] [] mce_cpu_callback+0x15e/0x1ad [ 207.272812] [] notifier_call_chain+0x72/0x130 [ 207.272824] [] __raw_notifier_call_chain+0xe/0x10 [ 207.272839] [] _cpu_down+0x1d6/0x350 [ 207.272851] [] cpu_down+0x40/0x60 [ 207.272862] [] store_online+0x75/0xe0 [ 207.272874] [] dev_attr_store+0x20/0x30 [ 207.272886] [] sysfs_write_file+0xd9/0x150 [ 207.272900] [] vfs_write+0xcb/0x130 [ 207.272911] [] sys_write+0x64/0xa0 [ 207.272923] [] system_call_fastpath+0x16/0x1b [ 207.272936] [ 207.272936] other info that might help us debug this: [ 207.272936] [ 207.272952] Chain exists of: [ 207.272952] subsys mutex --> &mm->mmap_sem --> cpu_hotplug.lock [ 207.272952] [ 207.272973] Possible unsafe locking scenario: [ 207.272973] [ 207.272984] CPU0 CPU1 [ 207.272992] ---- ---- [ 207.273000] lock(cpu_hotplug.lock); [ 207.273009] lock(&mm->mmap_sem); [ 207.273020] lock(cpu_hotplug.lock); [ 207.273031] lock(subsys mutex); [ 207.273040] [ 207.273040] *** DEADLOCK *** [ 207.273040] [ 207.273055] 5 locks held by bash/10493: [ 207.273062] #0: (&buffer->mutex){+.+.+.}, at: [] sysfs_write_file+0x49/0x150 [ 207.273080] #1: (s_active#150){.+.+.+}, at: [] sysfs_write_file+0xc2/0x150 [ 207.273099] #2: (x86_cpu_hotplug_driver_mutex){+.+.+.}, at: [] cpu_hotplug_driver_lock+0x17/0x20 [ 207.273121] #3: (cpu_add_remove_lock){+.+.+.}, at: [] cpu_down+0x2c/0x60 [ 207.273140] #4: (cpu_hotplug.lock){+.+.+.}, at: [] cpu_hotplug_begin+0x2f/0x60 [ 207.273158] [ 207.273158] stack backtrace: [ 207.273170] Pid: 10493, comm: bash Not tainted 3.9.0-rc1-0.7-default+ #34 [ 207.273180] Call Trace: [ 207.273192] [] print_circular_bug+0x223/0x310 [ 207.273204] [] __lock_acquire+0x13b2/0x15f0 [ 207.273216] [] ? sysfs_hash_and_remove+0x60/0xc0 [ 207.273227] [] lock_acquire+0xe9/0x120 [ 207.273239] [] ? bus_remove_device+0x37/0x1c0 [ 207.273251] [] mutex_lock_nested+0x37/0x360 [ 207.273263] [] ? bus_remove_device+0x37/0x1c0 [ 207.273274] [] ? sysfs_hash_and_remove+0x60/0xc0 [ 207.273286] [] bus_remove_device+0x37/0x1c0 [ 207.273298] [] device_del+0x134/0x1f0 [ 207.273309] [] device_unregister+0x22/0x60 [ 207.273321] [] mce_cpu_callback+0x15e/0x1ad [ 207.273332] [] notifier_call_chain+0x72/0x130 [ 207.273344] [] __raw_notifier_call_chain+0xe/0x10 [ 207.273356] [] _cpu_down+0x1d6/0x350 [ 207.273368] [] ? cpu_hotplug_driver_lock+0x17/0x20 [ 207.273380] [] cpu_down+0x40/0x60 [ 207.273391] [] store_online+0x75/0xe0 [ 207.273402] [] dev_attr_store+0x20/0x30 [ 207.273413] [] sysfs_write_file+0xd9/0x150 [ 207.273425] [] vfs_write+0xcb/0x130 [ 207.273436] [] sys_write+0x64/0xa0 [ 207.273447] [] system_call_fastpath+0x16/0x1b Which reports a false possitive deadlock because it sees: 1) load_module -> subsys_interface_register -> mc_deveice_add (*) -> subsys->p->mutex -> link_path_walk -> lookup_slow -> i_mutex 2) sys_write -> _cpu_down -> cpu_hotplug_begin -> cpu_hotplug.lock -> mce_cpu_callback -> mce_device_remove(**) -> device_unregister -> bus_remove_device -> subsys mutex 3) vfs_readdir -> i_mutex -> filldir64 -> might_fault -> might_lock_read(mmap_sem) -> page_fault -> mmap_sem -> drain_all_stock -> cpu_hotplug.lock but 1) takes cpu_subsys subsys (*) but 2) takes mce_device subsys (**) so the deadlock is not possible AFAICS. The fix is quite simple. We can pull the key inside bus_type structure because they are defined per device so the pointer will be unique as well. bus_register doesn't need to be a macro anymore so change it to the inline. We could get rid of __bus_register as there is no other caller but maybe somebody will want to use a different key so keep it around for now. Reported-by: Li Zefan Signed-off-by: Michal Hocko Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman --- include/linux/device.h | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index 9d6464ea99c6..4a7c4a84afee 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -111,17 +111,11 @@ struct bus_type { struct iommu_ops *iommu_ops; struct subsys_private *p; + struct lock_class_key lock_key; }; -/* This is a #define to keep the compiler from merging different - * instances of the __key variable */ -#define bus_register(subsys) \ -({ \ - static struct lock_class_key __key; \ - __bus_register(subsys, &__key); \ -}) -extern int __must_check __bus_register(struct bus_type *bus, - struct lock_class_key *key); +extern int __must_check bus_register(struct bus_type *bus); + extern void bus_unregister(struct bus_type *bus); extern int __must_check bus_rescan_devices(struct bus_type *bus); -- cgit v1.2.3 From 3c2670e6515cf584810f417db9b00992c8b2d75a Mon Sep 17 00:00:00 2001 From: Kay Sievers Date: Sat, 6 Apr 2013 09:56:00 -0700 Subject: driver core: add uid and gid to devtmpfs Some drivers want to tell userspace what uid and gid should be used for their device nodes, so allow that information to percolate through the driver core to userspace in order to make this happen. This means that some systems (i.e. Android and friends) will not need to even run a udev-like daemon for their device node manager and can just rely in devtmpfs fully, reducing their footprint even more. Signed-off-by: Kay Sievers Signed-off-by: Greg Kroah-Hartman --- include/linux/device.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index 4a7c4a84afee..851b85c7101e 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -25,6 +25,7 @@ #include #include #include +#include #include struct device; @@ -465,7 +466,8 @@ struct device_type { const char *name; const struct attribute_group **groups; int (*uevent)(struct device *dev, struct kobj_uevent_env *env); - char *(*devnode)(struct device *dev, umode_t *mode); + char *(*devnode)(struct device *dev, umode_t *mode, + uid_t *uid, gid_t *gid); void (*release)(struct device *dev); const struct dev_pm_ops *pm; @@ -843,7 +845,8 @@ extern int device_rename(struct device *dev, const char *new_name); extern int device_move(struct device *dev, struct device *new_parent, enum dpm_order dpm_order); extern const char *device_get_devnode(struct device *dev, - umode_t *mode, const char **tmp); + umode_t *mode, uid_t *uid, gid_t *gid, + const char **tmp); extern void *dev_get_drvdata(const struct device *dev); extern int dev_set_drvdata(struct device *dev, void *data); -- cgit v1.2.3 From 4e4098a3e08783cfd75f9fcdab276dc1d46931da Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 11 Apr 2013 11:43:29 -0700 Subject: driver core: handle user namespaces properly with the uid/gid devtmpfs change Now that devtmpfs is caring about uid/gid, we need to use the correct internal types so users who have USER_NS enabled will have things work properly for them. Thanks to Eric for pointing this out, and the patch review. Reported-by: Eric W. Biederman Cc: Kay Sievers Cc: Ming Lei Signed-off-by: Greg Kroah-Hartman --- include/linux/device.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index 851b85c7101e..88615ccaf23a 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -467,7 +467,7 @@ struct device_type { const struct attribute_group **groups; int (*uevent)(struct device *dev, struct kobj_uevent_env *env); char *(*devnode)(struct device *dev, umode_t *mode, - uid_t *uid, gid_t *gid); + kuid_t *uid, kgid_t *gid); void (*release)(struct device *dev); const struct dev_pm_ops *pm; @@ -845,7 +845,7 @@ extern int device_rename(struct device *dev, const char *new_name); extern int device_move(struct device *dev, struct device *new_parent, enum dpm_order dpm_order); extern const char *device_get_devnode(struct device *dev, - umode_t *mode, uid_t *uid, gid_t *gid, + umode_t *mode, kuid_t *uid, kgid_t *gid, const char **tmp); extern void *dev_get_drvdata(const struct device *dev); extern int dev_set_drvdata(struct device *dev, void *data); -- cgit v1.2.3