#ifndef _PERF_TARGET_H #define _PERF_TARGET_H #include #include struct target { const char *pid; const char *tid; const char *cpu_list; const char *uid_str; uid_t uid; bool system_wide; bool uses_mmap; bool default_per_cpu; bool per_thread; }; enum target_errno { TARGET_ERRNO__SUCCESS = 0, /* * Choose an arbitrary negative big number not to clash with standard * errno since SUS requires the errno has distinct positive values. * See 'Issue 6' in the link below. * * http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html */ __TARGET_ERRNO__START = -10000, /* for target__validate() */ TARGET_ERRNO__PID_OVERRIDE_CPU = __TARGET_ERRNO__START, TARGET_ERRNO__PID_OVERRIDE_UID, TARGET_ERRNO__UID_OVERRIDE_CPU, TARGET_ERRNO__PID_OVERRIDE_SYSTEM, TARGET_ERRNO__UID_OVERRIDE_SYSTEM, TARGET_ERRNO__SYSTEM_OVERRIDE_THREAD, /* for target__parse_uid() */ TARGET_ERRNO__INVALID_UID, TARGET_ERRNO__USER_NOT_FOUND, __TARGET_ERRNO__END, }; enum target_errno target__validate(struct target *target); enum target_errno target__parse_uid(struct target *target); int target__strerror(struct target *target, int errnum, char *buf, size_t buflen); static inline bool target__has_task(struct target *target) { return target->tid || target->pid || target->uid_str; } static inline bool target__has_cpu(struct target *target) { return target->system_wide || target->cpu_list; } static inline bool target__none(struct target *target) { return !target__has_task(target) && !target__has_cpu(target); } static inline bool target__uses_dummy_map(struct target *target) { bool use_dummy = false; if (target->default_per_cpu) use_dummy = target->per_thread ? true : false; else if (target__has_task(target) || (!target__has_cpu(target) && !target->uses_mmap)) use_dummy = true; return use_dummy; } #endif /* _PERF_TARGET_H */ id=966d2b04e070bc040319aaebfec09e0144dc3341'>treecommitdiff
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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 /tools/testing/selftests/x86/test_mremap_vdso.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 'tools/testing/selftests/x86/test_mremap_vdso.c')