https://github.com/torvalds/linux
Revision bd09d9a35111b6ffc0c7585d3853d0ec7f9f1eb4 authored by Greg Thelen on 30 October 2013, 20:56:20 UTC, committed by Linus Torvalds on 30 October 2013, 21:27:03 UTC
this_cpu_sub() is implemented as negation and addition. This patch casts the adjustment to the counter type before negation to sign extend the adjustment. This helps in cases where the counter type is wider than an unsigned adjustment. An alternative to this patch is to declare such operations unsupported, but it seemed useful to avoid surprises. This patch specifically helps the following example: unsigned int delta = 1 preempt_disable() this_cpu_write(long_counter, 0) this_cpu_sub(long_counter, delta) preempt_enable() Before this change long_counter on a 64 bit machine ends with value 0xffffffff, rather than 0xffffffffffffffff. This is because this_cpu_sub(pcp, delta) boils down to this_cpu_add(pcp, -delta), which is basically: long_counter = 0 + 0xffffffff Also apply the same cast to: __this_cpu_sub() __this_cpu_sub_return() this_cpu_sub_return() All percpu_test.ko passes, especially the following cases which previously failed: l -= ui_one; __this_cpu_sub(long_counter, ui_one); CHECK(l, long_counter, -1); l -= ui_one; this_cpu_sub(long_counter, ui_one); CHECK(l, long_counter, -1); CHECK(l, long_counter, 0xffffffffffffffff); ul -= ui_one; __this_cpu_sub(ulong_counter, ui_one); CHECK(ul, ulong_counter, -1); CHECK(ul, ulong_counter, 0xffffffffffffffff); ul = this_cpu_sub_return(ulong_counter, ui_one); CHECK(ul, ulong_counter, 2); ul = __this_cpu_sub_return(ulong_counter, ui_one); CHECK(ul, ulong_counter, 1); Signed-off-by: Greg Thelen <gthelen@google.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 3017f07
Tip revision: bd09d9a35111b6ffc0c7585d3853d0ec7f9f1eb4 authored by Greg Thelen on 30 October 2013, 20:56:20 UTC
percpu: fix this_cpu_sub() subtrahend casting for unsigneds
percpu: fix this_cpu_sub() subtrahend casting for unsigneds
Tip revision: bd09d9a
File | Mode | Size |
---|---|---|
fonts | ||
lz4 | ||
lzo | ||
mpi | ||
raid6 | ||
reed_solomon | ||
xz | ||
zlib_deflate | ||
zlib_inflate | ||
.gitignore | -rw-r--r-- | 70 bytes |
Kconfig | -rw-r--r-- | 9.5 KB |
Kconfig.debug | -rw-r--r-- | 52.8 KB |
Kconfig.kgdb | -rw-r--r-- | 3.1 KB |
Kconfig.kmemcheck | -rw-r--r-- | 2.9 KB |
Makefile | -rw-r--r-- | 5.8 KB |
argv_split.c | -rw-r--r-- | 2.1 KB |
asn1_decoder.c | -rw-r--r-- | 12.5 KB |
atomic64.c | -rw-r--r-- | 4.2 KB |
atomic64_test.c | -rw-r--r-- | 3.4 KB |
audit.c | -rw-r--r-- | 1.2 KB |
average.c | -rw-r--r-- | 1.9 KB |
bcd.c | -rw-r--r-- | 261 bytes |
bch.c | -rw-r--r-- | 35.6 KB |
bitmap.c | -rw-r--r-- | 34.7 KB |
bitrev.c | -rw-r--r-- | 2.1 KB |
bsearch.c | -rw-r--r-- | 1.6 KB |
btree.c | -rw-r--r-- | 19.2 KB |
bug.c | -rw-r--r-- | 4.8 KB |
build_OID_registry | -rwxr-xr-x | 4.7 KB |
bust_spinlocks.c | -rw-r--r-- | 660 bytes |
check_signature.c | -rw-r--r-- | 599 bytes |
checksum.c | -rw-r--r-- | 4.9 KB |
clz_ctz.c | -rw-r--r-- | 1009 bytes |
clz_tab.c | -rw-r--r-- | 855 bytes |
cmdline.c | -rw-r--r-- | 3.6 KB |
cordic.c | -rw-r--r-- | 2.5 KB |
cpu-notifier-error-inject.c | -rw-r--r-- | 1.2 KB |
cpu_rmap.c | -rw-r--r-- | 7.8 KB |
cpumask.c | -rw-r--r-- | 4.4 KB |
crc-ccitt.c | -rw-r--r-- | 3.0 KB |
crc-itu-t.c | -rw-r--r-- | 2.8 KB |
crc-t10dif.c | -rw-r--r-- | 1.5 KB |
crc16.c | -rw-r--r-- | 2.8 KB |
crc32.c | -rw-r--r-- | 42.1 KB |
crc32defs.h | -rw-r--r-- | 2.0 KB |
crc7.c | -rw-r--r-- | 2.3 KB |
crc8.c | -rw-r--r-- | 2.4 KB |
ctype.c | -rw-r--r-- | 1.4 KB |
debug_locks.c | -rw-r--r-- | 1.2 KB |
debugobjects.c | -rw-r--r-- | 26.2 KB |
dec_and_lock.c | -rw-r--r-- | 784 bytes |
decompress.c | -rw-r--r-- | 1.5 KB |
decompress_bunzip2.c | -rw-r--r-- | 23.4 KB |
decompress_inflate.c | -rw-r--r-- | 3.7 KB |
decompress_unlz4.c | -rw-r--r-- | 3.8 KB |
decompress_unlzma.c | -rw-r--r-- | 15.8 KB |
decompress_unlzo.c | -rw-r--r-- | 6.8 KB |
decompress_unxz.c | -rw-r--r-- | 10.6 KB |
devres.c | -rw-r--r-- | 10.2 KB |
digsig.c | -rw-r--r-- | 5.5 KB |
div64.c | -rw-r--r-- | 4.0 KB |
dma-debug.c | -rw-r--r-- | 34.9 KB |
dump_stack.c | -rw-r--r-- | 1.1 KB |
dynamic_debug.c | -rw-r--r-- | 25.3 KB |
dynamic_queue_limits.c | -rw-r--r-- | 4.3 KB |
earlycpio.c | -rw-r--r-- | 3.9 KB |
extable.c | -rw-r--r-- | 2.4 KB |
fault-inject.c | -rw-r--r-- | 5.5 KB |
fdt.c | -rw-r--r-- | 69 bytes |
fdt_ro.c | -rw-r--r-- | 72 bytes |
fdt_rw.c | -rw-r--r-- | 72 bytes |
fdt_strerror.c | -rw-r--r-- | 78 bytes |
fdt_sw.c | -rw-r--r-- | 72 bytes |
fdt_wip.c | -rw-r--r-- | 73 bytes |
find_last_bit.c | -rw-r--r-- | 1.1 KB |
find_next_bit.c | -rw-r--r-- | 6.4 KB |
flex_array.c | -rw-r--r-- | 10.9 KB |
flex_proportions.c | -rw-r--r-- | 6.8 KB |
gcd.c | -rw-r--r-- | 313 bytes |
gen_crc32table.c | -rw-r--r-- | 3.2 KB |
genalloc.c | -rw-r--r-- | 15.5 KB |
halfmd4.c | -rw-r--r-- | 2.0 KB |
hexdump.c | -rw-r--r-- | 7.2 KB |
hweight.c | -rw-r--r-- | 1.9 KB |
idr.c | -rw-r--r-- | 28.7 KB |
inflate.c | -rw-r--r-- | 38.6 KB |
int_sqrt.c | -rw-r--r-- | 652 bytes |
interval_tree.c | -rw-r--r-- | 297 bytes |
interval_tree_test_main.c | -rw-r--r-- | 2.3 KB |
iomap.c | -rw-r--r-- | 6.5 KB |
iomap_copy.c | -rw-r--r-- | 2.1 KB |
iommu-helper.c | -rw-r--r-- | 1.0 KB |
ioremap.c | -rw-r--r-- | 2.1 KB |
iovec.c | -rw-r--r-- | 1.0 KB |
irq_regs.c | -rw-r--r-- | 604 bytes |
is_single_threaded.c | -rw-r--r-- | 1.3 KB |
jedec_ddr_data.c | -rw-r--r-- | 3.0 KB |
kasprintf.c | -rw-r--r-- | 717 bytes |
kfifo.c | -rw-r--r-- | 12.7 KB |
klist.c | -rw-r--r-- | 9.3 KB |
kobject.c | -rw-r--r-- | 24.2 KB |
kobject_uevent.c | -rw-r--r-- | 10.4 KB |
kstrtox.c | -rw-r--r-- | 9.4 KB |
kstrtox.h | -rw-r--r-- | 254 bytes |
lcm.c | -rw-r--r-- | 288 bytes |
libcrc32c.c | -rw-r--r-- | 2.1 KB |
list_debug.c | -rw-r--r-- | 2.6 KB |
list_sort.c | -rw-r--r-- | 7.0 KB |
llist.c | -rw-r--r-- | 2.7 KB |
locking-selftest-hardirq.h | -rw-r--r-- | 207 bytes |
locking-selftest-mutex.h | -rw-r--r-- | 120 bytes |
locking-selftest-rlock-hardirq.h | -rw-r--r-- | 74 bytes |
locking-selftest-rlock-softirq.h | -rw-r--r-- | 74 bytes |
locking-selftest-rlock.h | -rw-r--r-- | 158 bytes |
locking-selftest-rsem.h | -rw-r--r-- | 163 bytes |
locking-selftest-softirq.h | -rw-r--r-- | 207 bytes |
locking-selftest-spin-hardirq.h | -rw-r--r-- | 73 bytes |
locking-selftest-spin-softirq.h | -rw-r--r-- | 73 bytes |
locking-selftest-spin.h | -rw-r--r-- | 118 bytes |
locking-selftest-wlock-hardirq.h | -rw-r--r-- | 74 bytes |
locking-selftest-wlock-softirq.h | -rw-r--r-- | 74 bytes |
locking-selftest-wlock.h | -rw-r--r-- | 158 bytes |
locking-selftest-wsem.h | -rw-r--r-- | 163 bytes |
locking-selftest.c | -rw-r--r-- | 40.1 KB |
lockref.c | -rw-r--r-- | 3.8 KB |
lru_cache.c | -rw-r--r-- | 19.2 KB |
md5.c | -rw-r--r-- | 3.7 KB |
memory-notifier-error-inject.c | -rw-r--r-- | 1.1 KB |
memweight.c | -rw-r--r-- | 999 bytes |
net_utils.c | -rw-r--r-- | 588 bytes |
nlattr.c | -rw-r--r-- | 12.4 KB |
notifier-error-inject.c | -rw-r--r-- | 2.7 KB |
notifier-error-inject.h | -rw-r--r-- | 614 bytes |
of-reconfig-notifier-error-inject.c | -rw-r--r-- | 1.3 KB |
oid_registry.c | -rw-r--r-- | 3.8 KB |
parser.c | -rw-r--r-- | 6.2 KB |
pci_iomap.c | -rw-r--r-- | 1.4 KB |
percpu-refcount.c | -rw-r--r-- | 5.7 KB |
percpu-rwsem.c | -rw-r--r-- | 5.0 KB |
percpu_counter.c | -rw-r--r-- | 5.1 KB |
percpu_ida.c | -rw-r--r-- | 8.2 KB |
plist.c | -rw-r--r-- | 4.7 KB |
pm-notifier-error-inject.c | -rw-r--r-- | 1.1 KB |
prio_heap.c | -rw-r--r-- | 1.4 KB |
proportions.c | -rw-r--r-- | 9.3 KB |
radix-tree.c | -rw-r--r-- | 40.0 KB |
random32.c | -rw-r--r-- | 5.2 KB |
ratelimit.c | -rw-r--r-- | 1.5 KB |
rational.c | -rw-r--r-- | 1.5 KB |
rbtree.c | -rw-r--r-- | 15.0 KB |
rbtree_test.c | -rw-r--r-- | 5.3 KB |
reciprocal_div.c | -rw-r--r-- | 218 bytes |
rwsem-spinlock.c | -rw-r--r-- | 6.5 KB |
rwsem.c | -rw-r--r-- | 7.9 KB |
scatterlist.c | -rw-r--r-- | 17.8 KB |
sha1.c | -rw-r--r-- | 6.1 KB |
show_mem.c | -rw-r--r-- | 1.4 KB |
smp_processor_id.c | -rw-r--r-- | 1.1 KB |
sort.c | -rw-r--r-- | 2.5 KB |
spinlock_debug.c | -rw-r--r-- | 7.1 KB |
stmp_device.c | -rw-r--r-- | 2.1 KB |
string.c | -rw-r--r-- | 16.2 KB |
string_helpers.c | -rw-r--r-- | 3.6 KB |
strncpy_from_user.c | -rw-r--r-- | 2.9 KB |
strnlen_user.c | -rw-r--r-- | 3.6 KB |
swiotlb.c | -rw-r--r-- | 26.7 KB |
syscall.c | -rw-r--r-- | 2.4 KB |
test-kstrtox.c | -rw-r--r-- | 17.4 KB |
test-string_helpers.c | -rw-r--r-- | 2.5 KB |
textsearch.c | -rw-r--r-- | 9.6 KB |
timerqueue.c | -rw-r--r-- | 3.1 KB |
ts_bm.c | -rw-r--r-- | 5.3 KB |
ts_fsm.c | -rw-r--r-- | 10.6 KB |
ts_kmp.c | -rw-r--r-- | 4.3 KB |
ucs2_string.c | -rw-r--r-- | 1.2 KB |
usercopy.c | -rw-r--r-- | 197 bytes |
uuid.c | -rw-r--r-- | 1.3 KB |
vsprintf.c | -rw-r--r-- | 57.6 KB |
Computing file changes ...