#ifdef __KERNEL__ # include #else # include "hash.h" #endif /* * Robert Jenkins' function for mixing 32-bit values * http://burtleburtle.net/bob/hash/evahash.html * a, b = random bits, c = input and output */ #define crush_hashmix(a, b, c) do { \ a = a-b; a = a-c; a = a^(c>>13); \ b = b-c; b = b-a; b = b^(a<<8); \ c = c-a; c = c-b; c = c^(b>>13); \ a = a-b; a = a-c; a = a^(c>>12); \ b = b-c; b = b-a; b = b^(a<<16); \ c = c-a; c = c-b; c = c^(b>>5); \ a = a-b; a = a-c; a = a^(c>>3); \ b = b-c; b = b-a; b = b^(a<<10); \ c = c-a; c = c-b; c = c^(b>>15); \ } while (0) #define crush_hash_seed 1315423911 static __u32 crush_hash32_rjenkins1(__u32 a) { __u32 hash = crush_hash_seed ^ a; __u32 b = a; __u32 x = 231232; __u32 y = 1232; crush_hashmix(b, x, hash); crush_hashmix(y, a, hash); return hash; } static __u32 crush_hash32_rjenkins1_2(__u32 a, __u32 b) { __u32 hash = crush_hash_seed ^ a ^ b; __u32 x = 231232; __u32 y = 1232; crush_hashmix(a, b, hash); crush_hashmix(x, a, hash); crush_hashmix(b, y, hash); return hash; } static __u32 crush_hash32_rjenkins1_3(__u32 a, __u32 b, __u32 c) { __u32 hash = crush_hash_seed ^ a ^ b ^ c; __u32 x = 231232; __u32 y = 1232; crush_hashmix(a, b, hash); crush_hashmix(c, x, hash); crush_hashmix(y, a, hash); crush_hashmix(b, x, hash); crush_hashmix(y, c, hash); return hash; } static __u32 crush_hash32_rjenkins1_4(__u32 a, __u32 b, __u32 c, __u32 d) { __u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d; __u32 x = 231232; __u32 y = 1232; crush_hashmix(a, b, hash); crush_hashmix(c, d, hash); crush_hashmix(a, x, hash); crush_hashmix(y, b, hash); crush_hashmix(c, x, hash); crush_hashmix(y, d, hash); return hash; } static __u32 crush_hash32_rjenkins1_5(__u32 a, __u32 b, __u32 c, __u32 d, __u32 e) { __u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d ^ e; __u32 x = 231232; __u32 y = 1232; crush_hashmix(a, b, hash); crush_hashmix(c, d, hash); crush_hashmix(e, x, hash); crush_hashmix(y, a, hash); crush_hashmix(b, x, hash); crush_hashmix(y, c, hash); crush_hashmix(d, x, hash); crush_hashmix(y, e, hash); return hash; } __u32 crush_hash32(int type, __u32 a) { switch (type) { case CRUSH_HASH_RJENKINS1: return crush_hash32_rjenkins1(a); default: return 0; } } __u32 crush_hash32_2(int type, __u32 a, __u32 b) { switch (type) { case CRUSH_HASH_RJENKINS1: return crush_hash32_rjenkins1_2(a, b); default: return 0; } } __u32 crush_hash32_3(int type, __u32 a, __u32 b, __u32 c) { switch (type) { case CRUSH_HASH_RJENKINS1: return crush_hash32_rjenkins1_3(a, b, c); default: return 0; } } __u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d) { switch (type) { case CRUSH_HASH_RJENKINS1: return crush_hash32_rjenkins1_4(a, b, c, d); default: return 0; } } __u32 crush_hash32_5(int type, __u32 a, __u32 b, __u32 c, __u32 d, __u32 e) { switch (type) { case CRUSH_HASH_RJENKINS1: return crush_hash32_rjenkins1_5(a, b, c, d, e); default: return 0; } } const char *crush_hash_name(int type) { switch (type) { case CRUSH_HASH_RJENKINS1: return "rjenkins1"; default: return "unknown"; } } de/dt-bindings/thermal
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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 /include/dt-bindings/thermal
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/dt-bindings/thermal')