/* * Copyright 2013-2015, Michael Ellerman, IBM Corp. * Licensed under GPLv2. */ #define _GNU_SOURCE /* For CPU_ZERO etc. */ #include #include #include #include #include #include #include #include #include #include "utils.h" static char auxv[4096]; void *get_auxv_entry(int type) { ElfW(auxv_t) *p; void *result; ssize_t num; int fd; fd = open("/proc/self/auxv", O_RDONLY); if (fd == -1) { perror("open"); return NULL; } result = NULL; num = read(fd, auxv, sizeof(auxv)); if (num < 0) { perror("read"); goto out; } if (num > sizeof(auxv)) { printf("Overflowed auxv buffer\n"); goto out; } p = (ElfW(auxv_t) *)auxv; while (p->a_type != AT_NULL) { if (p->a_type == type) { result = (void *)p->a_un.a_val; break; } p++; } out: close(fd); return result; } int pick_online_cpu(void) { cpu_set_t mask; int cpu; CPU_ZERO(&mask); if (sched_getaffinity(0, sizeof(mask), &mask)) { perror("sched_getaffinity"); return -1; } /* We prefer a primary thread, but skip 0 */ for (cpu = 8; cpu < CPU_SETSIZE; cpu += 8) if (CPU_ISSET(cpu, &mask)) return cpu; /* Search for anything, but in reverse */ for (cpu = CPU_SETSIZE - 1; cpu >= 0; cpu--) if (CPU_ISSET(cpu, &mask)) return cpu; printf("No cpus in affinity mask?!\n"); return -1; } switch'/> net-next plumbingsTobias Klauser
summaryrefslogtreecommitdiff
path: root/net/bluetooth/hidp/Kconfig
diff options
context:
space:
mode:
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 /net/bluetooth/hidp/Kconfig
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 'net/bluetooth/hidp/Kconfig')