/* * Copyright (C) 2016 Red Hat * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. * * Authors: * Rob Clark */ #ifndef DRM_PRINT_H_ #define DRM_PRINT_H_ #include #include /** * DOC: print * * A simple wrapper for dev_printk(), seq_printf(), etc. Allows same * debug code to be used for both debugfs and printk logging. * * For example:: * * void log_some_info(struct drm_printer *p) * { * drm_printf(p, "foo=%d\n", foo); * drm_printf(p, "bar=%d\n", bar); * } * * #ifdef CONFIG_DEBUG_FS * void debugfs_show(struct seq_file *f) * { * struct drm_printer p = drm_seq_file_printer(f); * log_some_info(&p); * } * #endif * * void some_other_function(...) * { * struct drm_printer p = drm_info_printer(drm->dev); * log_some_info(&p); * } */ /** * struct drm_printer - drm output "stream" * @printfn: actual output fxn * @arg: output fxn specific data * * Do not use struct members directly. Use drm_printer_seq_file(), * drm_printer_info(), etc to initialize. And drm_printf() for output. */ struct drm_printer { void (*printfn)(struct drm_printer *p, struct va_format *vaf); void *arg; }; void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf); void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf); void drm_printf(struct drm_printer *p, const char *f, ...); /** * drm_seq_file_printer - construct a &drm_printer that outputs to &seq_file * @f: the struct &seq_file to output to * * RETURNS: * The &drm_printer object */ static inline struct drm_printer drm_seq_file_printer(struct seq_file *f) { struct drm_printer p = { .printfn = __drm_printfn_seq_file, .arg = f, }; return p; } /** * drm_info_printer - construct a &drm_printer that outputs to dev_printk() * @dev: the struct &device pointer * * RETURNS: * The &drm_printer object */ static inline struct drm_printer drm_info_printer(struct device *dev) { struct drm_printer p = { .printfn = __drm_printfn_info, .arg = dev, }; return p; } #endif /* DRM_PRINT_H_ */ /commit/tools/perf?h=nds-private-remove&id=966d2b04e070bc040319aaebfec09e0144dc3341'>perf/util/debug.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 /tools/perf/util/debug.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/perf/util/debug.c')