/* * V4L2 asynchronous subdevice registration API * * Copyright (C) 2012-2013, Guennadi Liakhovetski * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #ifndef V4L2_ASYNC_H #define V4L2_ASYNC_H #include #include struct device; struct device_node; struct v4l2_device; struct v4l2_subdev; struct v4l2_async_notifier; /* A random max subdevice number, used to allocate an array on stack */ #define V4L2_MAX_SUBDEVS 128U /** * enum v4l2_async_match_type - type of asynchronous subdevice logic to be used * in order to identify a match * * @V4L2_ASYNC_MATCH_CUSTOM: Match will use the logic provided by &struct * v4l2_async_subdev.match ops * @V4L2_ASYNC_MATCH_DEVNAME: Match will use the device name * @V4L2_ASYNC_MATCH_I2C: Match will check for I2C adapter ID and address * @V4L2_ASYNC_MATCH_OF: Match will use OF node * * This enum is used by the asyncrhronous sub-device logic to define the * algorithm that will be used to match an asynchronous device. */ enum v4l2_async_match_type { V4L2_ASYNC_MATCH_CUSTOM, V4L2_ASYNC_MATCH_DEVNAME, V4L2_ASYNC_MATCH_I2C, V4L2_ASYNC_MATCH_OF, }; /** * struct v4l2_async_subdev - sub-device descriptor, as known to a bridge * * @match_type: type of match that will be used * @match: union of per-bus type matching data sets * @list: used to link struct v4l2_async_subdev objects, waiting to be * probed, to a notifier->waiting list */ struct v4l2_async_subdev { enum v4l2_async_match_type match_type; union { struct { const struct device_node *node; } of; struct { const char *name; } device_name; struct { int adapter_id; unsigned short address; } i2c; struct { bool (*match)(struct device *, struct v4l2_async_subdev *); void *priv; } custom; } match; /* v4l2-async core private: not to be used by drivers */ struct list_head list; }; /** * struct v4l2_async_notifier - v4l2_device notifier data * * @num_subdevs: number of subdevices * @subdevs: array of pointers to subdevice descriptors * @v4l2_dev: pointer to struct v4l2_device * @waiting: list of struct v4l2_async_subdev, waiting for their drivers * @done: list of struct v4l2_subdev, already probed * @list: member in a global list of notifiers * @bound: a subdevice driver has successfully probed one of subdevices * @complete: all subdevices have been probed successfully * @unbind: a subdevice is leaving */ struct v4l2_async_notifier { unsigned int num_subdevs; struct v4l2_async_subdev **subdevs; struct v4l2_device *v4l2_dev; struct list_head waiting; struct list_head done; struct list_head list; int (*bound)(struct v4l2_async_notifier *notifier, struct v4l2_subdev *subdev, struct v4l2_async_subdev *asd); int (*complete)(struct v4l2_async_notifier *notifier); void (*unbind)(struct v4l2_async_notifier *notifier, struct v4l2_subdev *subdev, struct v4l2_async_subdev *asd); }; /** * v4l2_async_notifier_register - registers a subdevice asynchronous notifier * * @v4l2_dev: pointer to &struct v4l2_device * @notifier: pointer to &struct v4l2_async_notifier */ int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev, struct v4l2_async_notifier *notifier); /** * v4l2_async_notifier_unregister - unregisters a subdevice asynchronous notifier * * @notifier: pointer to &struct v4l2_async_notifier */ void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier); /** * v4l2_async_register_subdev - registers a sub-device to the asynchronous * subdevice framework * * @sd: pointer to &struct v4l2_subdev */ int v4l2_async_register_subdev(struct v4l2_subdev *sd); /** * v4l2_async_unregister_subdev - unregisters a sub-device to the asynchronous * subdevice framework * * @sd: pointer to &struct v4l2_subdev */ void v4l2_async_unregister_subdev(struct v4l2_subdev *sd); #endif value='15'>15space:mode:
authorDouglas Miller <dougmill@linux.vnet.ibm.com>2017-01-28 06:42:20 -0600
committerTejun Heo <tj@kernel.org>2017-01-28 07:49:42 -0500
commit966d2b04e070bc040319aaebfec09e0144dc3341 (patch)
tree4b96156e3d1dd4dfd6039b7c219c9dc4616da52d /net/ife/Kconfig
parent1b1bc42c1692e9b62756323c675a44cb1a1f9dbd (diff)
percpu-refcount: fix reference leak during percpu-atomic transition
percpu_ref_tryget() and percpu_ref_tryget_live() should return "true" IFF they acquire a reference. But the return value from atomic_long_inc_not_zero() is a long and may have high bits set, e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines is bool so the reference may actually be acquired but the routines return "false" which results in a reference leak since the caller assumes it does not need to do a corresponding percpu_ref_put(). This was seen when performing CPU hotplug during I/O, as hangs in blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start) raced with percpu_ref_tryget (blk_mq_timeout_work). Sample stack trace: __switch_to+0x2c0/0x450 __schedule+0x2f8/0x970 schedule+0x48/0xc0 blk_mq_freeze_queue_wait+0x94/0x120 blk_mq_queue_reinit_work+0xb8/0x180 blk_mq_queue_reinit_prepare+0x84/0xa0 cpuhp_invoke_callback+0x17c/0x600 cpuhp_up_callbacks+0x58/0x150 _cpu_up+0xf0/0x1c0 do_cpu_up+0x120/0x150 cpu_subsys_online+0x64/0xe0 device_online+0xb4/0x120 online_store+0xb4/0xc0 dev_attr_store+0x68/0xa0 sysfs_kf_write+0x80/0xb0 kernfs_fop_write+0x17c/0x250 __vfs_write+0x6c/0x1e0 vfs_write+0xd0/0x270 SyS_write+0x6c/0x110 system_call+0x38/0xe0 Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS, and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests. However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0 and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set. The fix is to make the tryget routines use an actual boolean internally instead of the atomic long result truncated to a int. Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751 Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com> Reviewed-by: Jens Axboe <axboe@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints") Cc: stable@vger.kernel.org # v3.18+
Diffstat (limited to 'net/ife/Kconfig')