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[config]
command = stat
args    = kill >/dev/null 2>&1
ret     = 1

# PERF_TYPE_SOFTWARE / PERF_COUNT_SW_TASK_CLOCK
[event1:base-stat]
fd=1
type=1
config=1

# PERF_TYPE_SOFTWARE / PERF_COUNT_SW_CONTEXT_SWITCHES
[event2:base-stat]
fd=2
type=1
config=3

# PERF_TYPE_SOFTWARE / PERF_COUNT_SW_CPU_MIGRATIONS
[event3:base-stat]
fd=3
type=1
config=4

# PERF_TYPE_SOFTWARE / PERF_COUNT_SW_PAGE_FAULTS
[event4:base-stat]
fd=4
type=1
config=2

# PERF_TYPE_HARDWARE / PERF_COUNT_HW_CPU_CYCLES
[event5:base-stat]
fd=5
type=0
config=0

# PERF_TYPE_HARDWARE / PERF_COUNT_HW_STALLED_CYCLES_FRONTEND
[event6:base-stat]
fd=6
type=0
config=7

# PERF_TYPE_HARDWARE / PERF_COUNT_HW_STALLED_CYCLES_BACKEND
[event7:base-stat]
fd=7
type=0
config=8

# PERF_TYPE_HARDWARE / PERF_COUNT_HW_INSTRUCTIONS
[event8:base-stat]
fd=8
type=0
config=1

# PERF_TYPE_HARDWARE / PERF_COUNT_HW_BRANCH_INSTRUCTIONS
[event9:base-stat]
fd=9
type=0
config=4

# PERF_TYPE_HARDWARE / PERF_COUNT_HW_BRANCH_MISSES
[event10:base-stat]
fd=10
type=0
config=5
" 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/uapi/video/uvesafb.h')