static struct ins_ops *powerpc__associate_instruction_ops(struct arch *arch, const char *name) { int i; struct ins_ops *ops; /* * - Interested only if instruction starts with 'b'. * - Few start with 'b', but aren't branch instructions. */ if (name[0] != 'b' || !strncmp(name, "bcd", 3) || !strncmp(name, "brinc", 5) || !strncmp(name, "bper", 4)) return NULL; ops = &jump_ops; i = strlen(name) - 1; if (i < 0) return NULL; /* ignore optional hints at the end of the instructions */ if (name[i] == '+' || name[i] == '-') i--; if (name[i] == 'l' || (name[i] == 'a' && name[i-1] == 'l')) { /* * if the instruction ends up with 'l' or 'la', then * those are considered 'calls' since they update LR. * ... except for 'bnl' which is branch if not less than * and the absolute form of the same. */ if (strcmp(name, "bnl") && strcmp(name, "bnl+") && strcmp(name, "bnl-") && strcmp(name, "bnla") && strcmp(name, "bnla+") && strcmp(name, "bnla-")) ops = &call_ops; } if (name[i] == 'r' && name[i-1] == 'l') /* * instructions ending with 'lr' are considered to be * return instructions */ ops = &ret_ops; arch__associate_ins_ops(arch, name, ops); return ops; } static int powerpc__annotate_init(struct arch *arch) { if (!arch->initialized) { arch->initialized = true; arch->associate_instruction_ops = powerpc__associate_instruction_ops; arch->objdump.comment_char = '#'; } return 0; } >
summaryrefslogtreecommitdiff
path: root/include/linux/exportfs.h
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 /include/linux/exportfs.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 'include/linux/exportfs.h')