/* * v4l2-fh.h * * V4L2 file handle. Store per file handle data for the V4L2 * framework. Using file handles is optional for the drivers. * * Copyright (C) 2009--2010 Nokia Corporation. * * Contact: Sakari Ailus * * 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. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA * 02110-1301 USA */ #ifndef V4L2_FH_H #define V4L2_FH_H #include #include #include struct video_device; struct v4l2_ctrl_handler; /** * struct v4l2_fh - Describes a V4L2 file handler * * @list: list of file handlers * @vdev: pointer to &struct video_device * @ctrl_handler: pointer to &struct v4l2_ctrl_handler * @prio: priority of the file handler, as defined by &enum v4l2_priority * * @wait: event' s wait queue * @subscribed: list of subscribed events * @available: list of events waiting to be dequeued * @navailable: number of available events at @available list * @sequence: event sequence number * @m2m_ctx: pointer to &struct v4l2_m2m_ctx */ struct v4l2_fh { struct list_head list; struct video_device *vdev; struct v4l2_ctrl_handler *ctrl_handler; enum v4l2_priority prio; /* Events */ wait_queue_head_t wait; struct list_head subscribed; struct list_head available; unsigned int navailable; u32 sequence; #if IS_ENABLED(CONFIG_V4L2_MEM2MEM_DEV) struct v4l2_m2m_ctx *m2m_ctx; #endif }; /** * v4l2_fh_init - Initialise the file handle. * * @fh: pointer to &struct v4l2_fh * @vdev: pointer to &struct video_device * * Parts of the V4L2 framework using the * file handles should be initialised in this function. Must be called * from driver's v4l2_file_operations->open\(\) handler if the driver * uses &struct v4l2_fh. */ void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev); /** * v4l2_fh_add - Add the fh to the list of file handles on a video_device. * * @fh: pointer to &struct v4l2_fh * * .. note:: * The @fh file handle must be initialised first. */ void v4l2_fh_add(struct v4l2_fh *fh); /** * v4l2_fh_open - Ancillary routine that can be used as the open\(\) op * of v4l2_file_operations. * * @filp: pointer to struct file * * It allocates a v4l2_fh and inits and adds it to the &struct video_device * associated with the file pointer. */ int v4l2_fh_open(struct file *filp); /** * v4l2_fh_del - Remove file handle from the list of file handles. * * @fh: pointer to &struct v4l2_fh * * On error filp->private_data will be %NULL, otherwise it will point to * the &struct v4l2_fh. * * .. note:: * Must be called in v4l2_file_operations->release\(\) handler if the driver * uses &struct v4l2_fh. */ void v4l2_fh_del(struct v4l2_fh *fh); /** * v4l2_fh_exit - Release resources related to a file handle. * * @fh: pointer to &struct v4l2_fh * * Parts of the V4L2 framework using the v4l2_fh must release their * resources here, too. * * .. note:: * Must be called in v4l2_file_operations->release\(\) handler if the * driver uses &struct v4l2_fh. */ void v4l2_fh_exit(struct v4l2_fh *fh); /** * v4l2_fh_release - Ancillary routine that can be used as the release\(\) op * of v4l2_file_operations. * * @filp: pointer to struct file * * It deletes and exits the v4l2_fh associated with the file pointer and * frees it. It will do nothing if filp->private_data (the pointer to the * v4l2_fh struct) is %NULL. * * This function always returns 0. */ int v4l2_fh_release(struct file *filp); /** * v4l2_fh_is_singular - Returns 1 if this filehandle is the only filehandle * opened for the associated video_device. * * @fh: pointer to &struct v4l2_fh * * If @fh is NULL, then it returns 0. */ int v4l2_fh_is_singular(struct v4l2_fh *fh); /** * v4l2_fh_is_singular_file - Returns 1 if this filehandle is the only * filehandle opened for the associated video_device. * * @filp: pointer to struct file * * This is a helper function variant of v4l2_fh_is_singular() with uses * struct file as argument. * * If filp->private_data is %NULL, then it will return 0. */ static inline int v4l2_fh_is_singular_file(struct file *filp) { return v4l2_fh_is_singular(filp->private_data); } #endif /* V4L2_EVENT_H */ <tj@kernel.org>2017-01-28 07:49:42 -0500 commit966d2b04e070bc040319aaebfec09e0144dc3341 (patch) tree4b96156e3d1dd4dfd6039b7c219c9dc4616da52d /include/dt-bindings/clock 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 'include/dt-bindings/clock')