user/sven/linux.git/drivers/base/bus.c, branch v5.7

device.h: move 'struct bus' stuff out to device/bus.h

2019-12-16T09:11:12Z

device.h has everything and the kitchen sink when it comes to struct device things, so split out the struct bus things things to a separate .h file to make things easier to maintain and manage over time. Cc: "Rafael J. Wysocki" Cc: Suzuki K Poulose Cc: Saravana Kannan Cc: Heikki Krogerus Link: https://lore.kernel.org/r/20191209193303.1694546-5-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

drivers: Introduce device lookup variants by name

2019-07-30T11:07:41Z

Add a helper to match the device name for device lookup. Also reuse this generic exported helper for the existing bus_find_device_by_name(). and add similar variants for driver/class. Cc: Alessandro Zummo Cc: Alexander Aring Cc: Alexander Shishkin Cc: Arnd Bergmann Cc: Dan Murphy Cc: Harald Freudenberger Cc: Heiko Carstens Cc: Jacek Anaszewski Cc: Lee Jones Cc: linux-leds@vger.kernel.org Cc: linux-rtc@vger.kernel.org Cc: linux-usb@vger.kernel.org Cc: linux-wpan@vger.kernel.org Cc: Maxime Coquelin Cc: Pavel Machek Cc: Peter Oberparleiter Cc: "Rafael J. Wysocki" Cc: Stefan Schmidt Cc: Greg Kroah-Hartman Cc: "Rafael J. Wysocki" Signed-off-by: Suzuki K Poulose Reviewed-by: Heikki Krogerus Acked-by: Alexandre Belloni Link: https://lore.kernel.org/r/20190723221838.12024-2-suzuki.poulose@arm.com Signed-off-by: Greg Kroah-Hartman

bus_find_device: Unify the match callback with class_find_device

2019-06-24T03:22:31Z

There is an arbitrary difference between the prototypes of bus_find_device() and class_find_device() preventing their callers from passing the same pair of data and match() arguments to both of them, which is the const qualifier used in the prototype of class_find_device(). If that qualifier is also used in the bus_find_device() prototype, it will be possible to pass the same match() callback function to both bus_find_device() and class_find_device(), which will allow some optimizations to be made in order to avoid code duplication going forward. Also with that, constify the "data" parameter as it is passed as a const to the match function. For this reason, change the prototype of bus_find_device() to match the prototype of class_find_device() and adjust its callers to use the const qualifier in accordance with the new prototype of it. Cc: Alexander Shishkin Cc: Andrew Lunn Cc: Andreas Noever Cc: Arnd Bergmann Cc: Bjorn Helgaas Cc: Corey Minyard Cc: Christian Borntraeger Cc: David Kershner Cc: "David S. Miller" Cc: David Airlie Cc: Felipe Balbi Cc: Frank Rowand Cc: Grygorii Strashko Cc: Harald Freudenberger Cc: Hartmut Knaack Cc: Heiko Stuebner Cc: Jason Gunthorpe Cc: Jonathan Cameron Cc: "James E.J. Bottomley" Cc: Len Brown Cc: Mark Brown Cc: Michael Ellerman Cc: Michael Jamet Cc: "Martin K. Petersen" Cc: Peter Oberparleiter Cc: Sebastian Ott Cc: Srinivas Kandagatla Cc: Yehezkel Bernat Cc: rafael@kernel.org Acked-by: Corey Minyard Acked-by: David Kershner Acked-by: Mark Brown Acked-by: Rafael J. Wysocki Acked-by: Srinivas Kandagatla Acked-by: Wolfram Sang # for the I2C parts Acked-by: Rob Herring Signed-off-by: Suzuki K Poulose Signed-off-by: Greg Kroah-Hartman

driver core: Probe devices asynchronously instead of the driver

2019-01-31T13:20:53Z

Probe devices asynchronously instead of the driver. This results in us seeing the same behavior if the device is registered before the driver or after. This way we can avoid serializing the initialization should the driver not be loaded until after the devices have already been added. The motivation behind this is that if we have a set of devices that take a significant amount of time to load we can greatly reduce the time to load by processing them in parallel instead of one at a time. In addition, each device can exist on a different node so placing a single thread on one CPU to initialize all of the devices for a given driver can result in poor performance on a system with multiple nodes. This approach can reduce the time needed to scan SCSI LUNs significantly. The only way to realize that speedup is by enabling more concurrency which is what is achieved with this patch. To achieve this it was necessary to add a new member "async_driver" to the device_private structure to store the driver pointer while we wait on the deferred probe call. Reviewed-by: Bart Van Assche Reviewed-by: Dan Williams Signed-off-by: Alexander Duyck Reviewed-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

device core: Consolidate locking and unlocking of parent and device

2019-01-31T13:20:53Z

Try to consolidate all of the locking and unlocking of both the parent and device when attaching or removing a driver from a given device. To do that I first consolidated the lock pattern into two functions __device_driver_lock and __device_driver_unlock. After doing that I then created functions specific to attaching and detaching the driver while acquiring these locks. By doing this I was able to reduce the number of spots where we touch need_parent_lock from 12 down to 4. This patch should produce no functional changes, it is meant to be a code clean-up/consolidation only. Reviewed-by: Luis Chamberlain Reviewed-by: Bart Van Assche Reviewed-by: Dan Williams Reviewed-by: Rafael J. Wysocki Signed-off-by: Alexander Duyck Signed-off-by: Greg Kroah-Hartman

driver core: drop use of BUS_ATTR()

2019-01-08T14:18:55Z

We are trying to get rid of BUS_ATTR() so drop the last user of it from the tree. We had to "open code" it in order to prevent a function name conflict due to the use of DEVICE_ATTR_WO() earlier in the file :( Cc: "Rafael J. Wysocki" Signed-off-by: Greg Kroah-Hartman

driver core: bus: convert to use BUS_ATTR_WO and RW

2019-01-08T14:18:52Z

We are trying to get rid of BUS_ATTR() and the usage of that in bus.c can be trivially converted to use BUS_ATTR_WO and RW, so use those macros instead. Cc: "Rafael J. Wysocki" Signed-off-by: Greg Kroah-Hartman

sysfs: Disable lockdep for driver bind/unbind files

2018-12-19T14:58:40Z

This is the much more correct fix for my earlier attempt at: https://lkml.org/lkml/2018/12/10/118 Short recap: - There's not actually a locking issue, it's just lockdep being a bit too eager to complain about a possible deadlock. - Contrary to what I claimed the real problem is recursion on kn->count. Greg pointed me at sysfs_break_active_protection(), used by the scsi subsystem to allow a sysfs file to unbind itself. That would be a real deadlock, which isn't what's happening here. Also, breaking the active protection means we'd need to manually handle all the lifetime fun. - With Rafael we discussed the task_work approach, which kinda works, but has two downsides: It's a functional change for a lockdep annotation issue, and it won't work for the bind file (which needs to get the errno from the driver load function back to userspace). - Greg also asked why this never showed up: To hit this you need to unregister a 2nd driver from the unload code of your first driver. I guess only gpus do that. The bug has always been there, but only with a recent patch series did we add more locks so that lockdep built a chain from unbinding the snd-hda driver to the acpi_video_unregister call. Full lockdep splat: [12301.898799] ============================================ [12301.898805] WARNING: possible recursive locking detected [12301.898811] 4.20.0-rc7+ #84 Not tainted [12301.898815] -------------------------------------------- [12301.898821] bash/5297 is trying to acquire lock: [12301.898826] 00000000f61c6093 (kn->count#39){++++}, at: kernfs_remove_by_name_ns+0x3b/0x80 [12301.898841] but task is already holding lock: [12301.898847] 000000005f634021 (kn->count#39){++++}, at: kernfs_fop_write+0xdc/0x190 [12301.898856] other info that might help us debug this: [12301.898862] Possible unsafe locking scenario: [12301.898867] CPU0 [12301.898870] ---- [12301.898874] lock(kn->count#39); [12301.898879] lock(kn->count#39); [12301.898883] *** DEADLOCK *** [12301.898891] May be due to missing lock nesting notation [12301.898899] 5 locks held by bash/5297: [12301.898903] #0: 00000000cd800e54 (sb_writers#4){.+.+}, at: vfs_write+0x17f/0x1b0 [12301.898915] #1: 000000000465e7c2 (&of->mutex){+.+.}, at: kernfs_fop_write+0xd3/0x190 [12301.898925] #2: 000000005f634021 (kn->count#39){++++}, at: kernfs_fop_write+0xdc/0x190 [12301.898936] #3: 00000000414ef7ac (&dev->mutex){....}, at: device_release_driver_internal+0x34/0x240 [12301.898950] #4: 000000003218fbdf (register_count_mutex){+.+.}, at: acpi_video_unregister+0xe/0x40 [12301.898960] stack backtrace: [12301.898968] CPU: 1 PID: 5297 Comm: bash Not tainted 4.20.0-rc7+ #84 [12301.898974] Hardware name: Hewlett-Packard HP EliteBook 8460p/161C, BIOS 68SCF Ver. F.01 03/11/2011 [12301.898982] Call Trace: [12301.898989] dump_stack+0x67/0x9b [12301.898997] __lock_acquire+0x6ad/0x1410 [12301.899003] ? kernfs_remove_by_name_ns+0x3b/0x80 [12301.899010] ? find_held_lock+0x2d/0x90 [12301.899017] ? mutex_spin_on_owner+0xe4/0x150 [12301.899023] ? find_held_lock+0x2d/0x90 [12301.899030] ? lock_acquire+0x90/0x180 [12301.899036] lock_acquire+0x90/0x180 [12301.899042] ? kernfs_remove_by_name_ns+0x3b/0x80 [12301.899049] __kernfs_remove+0x296/0x310 [12301.899055] ? kernfs_remove_by_name_ns+0x3b/0x80 [12301.899060] ? kernfs_name_hash+0xd/0x80 [12301.899066] ? kernfs_find_ns+0x6c/0x100 [12301.899073] kernfs_remove_by_name_ns+0x3b/0x80 [12301.899080] bus_remove_driver+0x92/0xa0 [12301.899085] acpi_video_unregister+0x24/0x40 [12301.899127] i915_driver_unload+0x42/0x130 [i915] [12301.899160] i915_pci_remove+0x19/0x30 [i915] [12301.899169] pci_device_remove+0x36/0xb0 [12301.899176] device_release_driver_internal+0x185/0x240 [12301.899183] unbind_store+0xaf/0x180 [12301.899189] kernfs_fop_write+0x104/0x190 [12301.899195] __vfs_write+0x31/0x180 [12301.899203] ? rcu_read_lock_sched_held+0x6f/0x80 [12301.899209] ? rcu_sync_lockdep_assert+0x29/0x50 [12301.899216] ? __sb_start_write+0x13c/0x1a0 [12301.899221] ? vfs_write+0x17f/0x1b0 [12301.899227] vfs_write+0xb9/0x1b0 [12301.899233] ksys_write+0x50/0xc0 [12301.899239] do_syscall_64+0x4b/0x180 [12301.899247] entry_SYSCALL_64_after_hwframe+0x49/0xbe [12301.899253] RIP: 0033:0x7f452ac7f7a4 [12301.899259] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 80 00 00 00 00 8b 05 aa f0 2c 00 48 63 ff 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 f3 c3 66 90 55 53 48 89 d5 48 89 f3 48 83 [12301.899273] RSP: 002b:00007ffceafa6918 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [12301.899282] RAX: ffffffffffffffda RBX: 000000000000000d RCX: 00007f452ac7f7a4 [12301.899288] RDX: 000000000000000d RSI: 00005612a1abf7c0 RDI: 0000000000000001 [12301.899295] RBP: 00005612a1abf7c0 R08: 000000000000000a R09: 00005612a1c46730 [12301.899301] R10: 000000000000000a R11: 0000000000000246 R12: 000000000000000d [12301.899308] R13: 0000000000000001 R14: 00007f452af4a740 R15: 000000000000000d Looking around I've noticed that usb and i2c already handle similar recursion problems, where a sysfs file can unbind the same type of sysfs somewhere else in the hierarchy. Relevant commits are: commit 356c05d58af05d582e634b54b40050c73609617b Author: Alan Stern Date: Mon May 14 13:30:03 2012 -0400 sysfs: get rid of some lockdep false positives commit e9b526fe704812364bca07edd15eadeba163ebfb Author: Alexander Sverdlin Date: Fri May 17 14:56:35 2013 +0200 i2c: suppress lockdep warning on delete_device Implement the same trick for driver bind/unbind. v2: Put the macro into bus.c (Greg). Reviewed-by: Rafael J. Wysocki Cc: Ramalingam C Cc: Arend van Spriel Cc: Andy Shevchenko Cc: Geert Uytterhoeven Cc: Bartosz Golaszewski Cc: Heikki Krogerus Cc: Vivek Gautam Cc: Joe Perches Signed-off-by: Daniel Vetter Signed-off-by: Greg Kroah-Hartman

kobject: return error code if writing /sys/.../uevent fails

2018-12-06T15:07:43Z

Propagate error code back to userspace if writing the /sys/.../uevent file fails. Before, the write operation always returned with success, even if we failed to recognize the input string or if we failed to generate the uevent itself. With the error codes properly propagated back to userspace, we are able to react in userspace accordingly by not assuming and awaiting a uevent that is not delivered. Signed-off-by: Peter Rajnoha Signed-off-by: Greg Kroah-Hartman

driver core: hold dev's parent lock when needed

2018-05-31T08:12:07Z

SoC have internal I/O buses that can't be proved for devices. The devices on the buses can be accessed directly without additinal configuration required. This type of bus is represented as "simple-bus". In some platforms, we name "soc" with "simple-bus" attribute and many devices are hooked under it described in DT (device tree). In commit bf74ad5bc417 ("Hold the device's parent's lock during probe and remove") to solve USB subsystem lock sequence since USB device's characteristic. Thus "soc" needs to be locked whenever a device and driver's probing happen under "soc" bus. During this period, an async driver tries to probe a device which is under the "soc" bus would be blocked until previous driver finish the probing and release "soc" lock. And the next probing under the "soc" bus need to wait for async finish. Because of that, driver's async probe for init time improvement will be shadowed. Since many devices don't have USB devices' characteristic, they actually don't need parent's lock. Thus, we introduce a lock flag in bus_type struct and driver core would lock the parent lock base on the flag. For USB, we set this flag in usb_bus_type to keep original lock behavior in driver core. Async probe could have more benefit after this patch. Signed-off-by: Martin Liu Acked-by: Alan Stern Signed-off-by: Greg Kroah-Hartman