#include #include #include #ifndef O_DIRECT #define O_DIRECT 00040000 #endif #ifndef O_DIRECTORY #define O_DIRECTORY 00200000 #endif #ifndef O_NOATIME #define O_NOATIME 01000000 #endif static size_t syscall_arg__scnprintf_open_flags(char *bf, size_t size, struct syscall_arg *arg) { int printed = 0, flags = arg->val; if (!(flags & O_CREAT)) arg->mask |= 1 << (arg->idx + 1); /* Mask the mode parm */ if (flags == 0) return scnprintf(bf, size, "RDONLY"); #define P_FLAG(n) \ if (flags & O_##n) { \ printed += scnprintf(bf + printed, size - printed, "%s%s", printed ? "|" : "", #n); \ flags &= ~O_##n; \ } P_FLAG(APPEND); P_FLAG(ASYNC); P_FLAG(CLOEXEC); P_FLAG(CREAT); P_FLAG(DIRECT); P_FLAG(DIRECTORY); P_FLAG(EXCL); P_FLAG(LARGEFILE); P_FLAG(NOATIME); P_FLAG(NOCTTY); #ifdef O_NONBLOCK P_FLAG(NONBLOCK); #elif O_NDELAY P_FLAG(NDELAY); #endif #ifdef O_PATH P_FLAG(PATH); #endif P_FLAG(RDWR); #ifdef O_DSYNC if ((flags & O_SYNC) == O_SYNC) printed += scnprintf(bf + printed, size - printed, "%s%s", printed ? "|" : "", "SYNC"); else { P_FLAG(DSYNC); } #else P_FLAG(SYNC); #endif P_FLAG(TRUNC); P_FLAG(WRONLY); #undef P_FLAG if (flags) printed += scnprintf(bf + printed, size - printed, "%s%#x", printed ? "|" : "", flags); return printed; } #define SCA_OPEN_FLAGS syscall_arg__scnprintf_open_flags lue='switch'/> net-next plumbingsTobias Klauser
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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 /sound/pci/aw2/aw2-saa7146.h
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 'sound/pci/aw2/aw2-saa7146.h')