/****************************************************************************** ******************************************************************************* ** ** Copyright (C) 2005-2007 Red Hat, Inc. All rights reserved. ** ** This copyrighted material is made available to anyone wishing to use, ** modify, copy, or redistribute it subject to the terms and conditions ** of the GNU General Public License v.2. ** ******************************************************************************* ******************************************************************************/ #ifndef __LOCK_DOT_H__ #define __LOCK_DOT_H__ void dlm_dump_rsb(struct dlm_rsb *r); void dlm_dump_rsb_name(struct dlm_ls *ls, char *name, int len); void dlm_print_lkb(struct dlm_lkb *lkb); void dlm_receive_message_saved(struct dlm_ls *ls, struct dlm_message *ms, uint32_t saved_seq); void dlm_receive_buffer(union dlm_packet *p, int nodeid); int dlm_modes_compat(int mode1, int mode2); void dlm_put_rsb(struct dlm_rsb *r); void dlm_hold_rsb(struct dlm_rsb *r); int dlm_put_lkb(struct dlm_lkb *lkb); void dlm_scan_rsbs(struct dlm_ls *ls); int dlm_lock_recovery_try(struct dlm_ls *ls); void dlm_unlock_recovery(struct dlm_ls *ls); void dlm_scan_waiters(struct dlm_ls *ls); void dlm_scan_timeout(struct dlm_ls *ls); void dlm_adjust_timeouts(struct dlm_ls *ls); int dlm_master_lookup(struct dlm_ls *ls, int nodeid, char *name, int len, unsigned int flags, int *r_nodeid, int *result); int dlm_search_rsb_tree(struct rb_root *tree, char *name, int len, struct dlm_rsb **r_ret); void dlm_recover_purge(struct dlm_ls *ls); void dlm_purge_mstcpy_locks(struct dlm_rsb *r); void dlm_recover_grant(struct dlm_ls *ls); int dlm_recover_waiters_post(struct dlm_ls *ls); void dlm_recover_waiters_pre(struct dlm_ls *ls); int dlm_recover_master_copy(struct dlm_ls *ls, struct dlm_rcom *rc); int dlm_recover_process_copy(struct dlm_ls *ls, struct dlm_rcom *rc); int dlm_user_request(struct dlm_ls *ls, struct dlm_user_args *ua, int mode, uint32_t flags, void *name, unsigned int namelen, unsigned long timeout_cs); int dlm_user_convert(struct dlm_ls *ls, struct dlm_user_args *ua_tmp, int mode, uint32_t flags, uint32_t lkid, char *lvb_in, unsigned long timeout_cs); int dlm_user_adopt_orphan(struct dlm_ls *ls, struct dlm_user_args *ua_tmp, int mode, uint32_t flags, void *name, unsigned int namelen, unsigned long timeout_cs, uint32_t *lkid); int dlm_user_unlock(struct dlm_ls *ls, struct dlm_user_args *ua_tmp, uint32_t flags, uint32_t lkid, char *lvb_in); int dlm_user_cancel(struct dlm_ls *ls, struct dlm_user_args *ua_tmp, uint32_t flags, uint32_t lkid); int dlm_user_purge(struct dlm_ls *ls, struct dlm_user_proc *proc, int nodeid, int pid); int dlm_user_deadlock(struct dlm_ls *ls, uint32_t flags, uint32_t lkid); void dlm_clear_proc_locks(struct dlm_ls *ls, struct dlm_user_proc *proc); static inline int is_master(struct dlm_rsb *r) { return !r->res_nodeid; } static inline void lock_rsb(struct dlm_rsb *r) { mutex_lock(&r->res_mutex); } static inline void unlock_rsb(struct dlm_rsb *r) { mutex_unlock(&r->res_mutex); } #endif /linux/net-next.git/commit/drivers?h=nds-private-remove&id=966d2b04e070bc040319aaebfec09e0144dc3341'>drivers/usb/gadget/composite.c
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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 /drivers/usb/gadget/composite.c
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 'drivers/usb/gadget/composite.c')