Repository files (latest commit first)

Filename	Latest commit message	Latest commit date
Linus Torvalds bc08b449ee lockref: implement lockless reference count updates using cmpxchg() ... Instead of taking the spinlock, the lockless versions atomically check that the lock is not taken, and do the reference count update using a cmpxchg() loop. This is semantically identical to doing the reference count update protected by the lock, but avoids the "wait for lock" contention that you get when accesses to the reference count are contended. Note that a "lockref" is absolutely _not_ equivalent to an atomic_t. Even when the lockref reference counts are updated atomically with cmpxchg, the fact that they also verify the state of the spinlock means that the lockless updates can never happen while somebody else holds the spinlock. So while "lockref_put_or_lock()" looks a lot like just another name for "atomic_dec_and_lock()", and both optimize to lockless updates, they are fundamentally different: the decrement done by atomic_dec_and_lock() is truly independent of any lock (as long as it doesn't decrement to zero), so a locked region can still see the count change. The lockref structure, in contrast, really is a *locked* reference count. If you hold the spinlock, the reference count will be stable and you can modify the reference count without using atomics, because even the lockless updates will see and respect the state of the lock. In order to enable the cmpxchg lockless code, the architecture needs to do three things: (1) Make sure that the "arch_spinlock_t" and an "unsigned int" can fit in an aligned u64, and have a "cmpxchg()" implementation that works on such a u64 data type. (2) define a helper function to test for a spinlock being unlocked ("arch_spin_value_unlocked()") (3) select the "ARCH_USE_CMPXCHG_LOCKREF" config variable in its Kconfig file. This enables it for x86-64 (but not 32-bit, we'd need to make sure cmpxchg() turns into the proper cmpxchg8b in order to enable it for 32-bit mode). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2013-09-02 12:12:15 -07:00
..
fonts	lib: Move fonts from drivers/video/console/ to lib/fonts/	2013-06-28 10:28:22 +02:00
lz4	lib/lz4: correct the LZ4 license	2013-08-23 09:51:22 -07:00
lzo	lib/lzo: Update LZO compression to current upstream version	2013-02-20 19:36:01 +01:00
mpi	alpha: Modernize lib/mpi/longlong.h	2013-07-19 13:54:23 -07:00
raid6	lib/raid6: build proper files on corresponding arch	2012-12-13 19:51:04 +11:00
reed_solomon
xz	decompressors: fix typo "POWERPC"	2013-03-13 15:21:48 -07:00
zlib_deflate
zlib_inflate
.gitignore
argv_split.c	argv_split(): teach it to handle mutable strings	2013-04-29 18:28:19 -07:00
asn1_decoder.c	Nothing all that exciting; a new module-from-fd syscall for those who want	2012-12-19 07:55:08 -08:00
atomic64.c	lib: atomic64: Initialize locks statically to fix early users	2012-12-20 13:50:16 -08:00
atomic64_test.c
audit.c
average.c
bcd.c
bch.c
bitmap.c
bitrev.c
bsearch.c
btree.c
bug.c	taint: add explicit flag to show whether lock dep is still OK.	2013-01-21 17:17:57 +10:30
build_OID_registry	X.509: do not emit any informational output	2013-06-19 17:54:06 +02:00
bust_spinlocks.c	printk: Provide a wake_up_klogd() off-case	2013-03-22 16:41:20 -07:00
check_signature.c
checksum.c	asm-generic headers: Allow yet more arch overrides in checksum.h	2013-02-11 20:00:33 +05:30
clz_ctz.c	lib: add weak clz/ctz functions	2013-07-09 10:33:30 -07:00
clz_tab.c
cmdline.c
cordic.c
cpu-notifier-error-inject.c
cpu_rmap.c	lib: cpu_rmap: avoid flushing all workqueues	2013-01-11 14:54:54 -08:00
cpumask.c	bootmem: fix wrong call parameter for free_bootmem()	2012-12-11 17:22:28 -08:00
crc-ccitt.c
crc-itu-t.c
crc-t10dif.c	Revert "crypto: crct10dif - Wrap crc_t10dif function all to use crypto transform framework"	2013-07-24 17:04:16 +10:00
crc7.c
crc8.c
crc16.c
crc32.c
crc32defs.h
ctype.c
debug_locks.c	mutex: Add support for wound/wait style locks	2013-06-26 12:10:56 +02:00
debugobjects.c	hlist: drop the node parameter from iterators	2013-02-27 19:10:24 -08:00
dec_and_lock.c
decompress.c	lib: add support for LZ4-compressed kernel	2013-07-09 10:33:30 -07:00
decompress_bunzip2.c
decompress_inflate.c
decompress_unlz4.c	lib: add support for LZ4-compressed kernel	2013-07-09 10:33:30 -07:00
decompress_unlzma.c
decompress_unlzo.c	lib/lzo: Rename lzo1x_decompress.c to lzo1x_decompress_safe.c	2013-02-20 19:36:00 +01:00
decompress_unxz.c
devres.c	lib/devres.c: fix misplaced #endif	2013-02-27 19:10:09 -08:00
digsig.c	Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2013-02-21 08:18:12 -08:00
div64.c	Revert "math64: New div64_u64_rem helper"	2013-04-30 19:13:05 +02:00
dma-debug.c	dma-debug: update DMA debug API to better handle multiple mappings of a buffer	2013-03-22 16:41:20 -07:00
dump_stack.c	dump_stack: serialize the output from dump_stack()	2013-07-03 16:07:41 -07:00
dynamic_debug.c	dynamic_debug: reuse generic string_unescape function	2013-04-30 17:04:03 -07:00
dynamic_queue_limits.c
earlycpio.c	kernel: delete __cpuinit usage from all core kernel files	2013-07-14 19:36:59 -04:00
extable.c
fault-inject.c	debugfs: add get/set for atomic types	2013-06-03 13:55:01 -07:00
fdt.c
fdt_ro.c
fdt_rw.c
fdt_strerror.c
fdt_sw.c
fdt_wip.c
find_last_bit.c
find_next_bit.c
flex_array.c
flex_proportions.c
gcd.c
gen_crc32table.c
genalloc.c	genalloc: add devres support, allow to find a managed pool by device	2013-04-29 18:28:13 -07:00
halfmd4.c
hexdump.c	dynamic_debug: dynamic hex dump	2013-01-17 12:19:09 -08:00
hweight.c
idr.c	idr: print a stack dump after ida_remove warning	2013-07-03 16:08:04 -07:00
inflate.c
int_sqrt.c	lib/int_sqrt.c: optimize square root algorithm	2013-04-29 18:28:19 -07:00
interval_tree.c
interval_tree_test_main.c	random32: rename random32 to prandom	2012-12-17 17:15:26 -08:00
iomap.c
iomap_copy.c
iommu-helper.c
ioremap.c
iovec.c	Hoist memcpy_fromiovec/memcpy_toiovec into lib/	2013-05-20 10:24:22 +09:30
irq_regs.c
is_single_threaded.c
jedec_ddr_data.c
kasprintf.c
Kconfig	lockref: implement lockless reference count updates using cmpxchg()	2013-09-02 12:12:15 -07:00
Kconfig.debug	kernel: delete __cpuinit usage from all core kernel files	2013-07-14 19:36:59 -04:00
Kconfig.kgdb	treewide: Fix typo in printk	2013-06-18 13:48:45 +02:00
Kconfig.kmemcheck
kfifo.c	kfifo: fix kfifo_alloc() and kfifo_init()	2013-02-27 19:10:23 -08:00
klist.c	klist: del waiter from klist_remove_waiters before wakeup waitting process	2013-05-21 10:16:39 -07:00
kobject.c	kobject: sanitize argument for format string	2013-06-07 16:05:50 -07:00
kobject_uevent.c
kstrtox.c	kstrto*: add documentation	2012-12-17 17:15:22 -08:00
kstrtox.h
lcm.c
libcrc32c.c
list_debug.c
list_sort.c	lib/: rename random32() to prandom_u32()	2013-04-29 18:28:42 -07:00
llist.c	llist: fix/simplify llist_add() and llist_add_batch()	2013-07-13 13:29:24 +04:00
locking-selftest-hardirq.h
locking-selftest-mutex.h
locking-selftest-rlock-hardirq.h
locking-selftest-rlock-softirq.h
locking-selftest-rlock.h
locking-selftest-rsem.h
locking-selftest-softirq.h
locking-selftest-spin-hardirq.h
locking-selftest-spin-softirq.h
locking-selftest-spin.h
locking-selftest-wlock-hardirq.h
locking-selftest-wlock-softirq.h
locking-selftest-wlock.h
locking-selftest-wsem.h
locking-selftest.c	mutex: Move ww_mutex definitions to ww_mutex.h	2013-07-12 12:07:46 +02:00
lockref.c	lockref: implement lockless reference count updates using cmpxchg()	2013-09-02 12:12:15 -07:00
lru_cache.c	lru_cache: introduce lc_get_cumulative()	2013-03-22 22:17:36 -06:00
Makefile	lockref: uninline lockref helper functions	2013-09-02 11:58:20 -07:00
md5.c
memory-notifier-error-inject.c
memweight.c
net_utils.c	net: core: move mac_pton() to lib/net_utils.c	2013-06-05 12:00:27 -07:00
nlattr.c
notifier-error-inject.c	mode_t, whack-a-mole at 11...	2013-04-09 14:13:05 -04:00
notifier-error-inject.h
of-reconfig-notifier-error-inject.c	powerpc+of: Rename and fix OF reconfig notifier error inject module	2012-12-14 10:32:52 +11:00
oid_registry.c	Give the OID registry file module info to avoid kernel tainting	2013-05-05 14:38:00 -07:00
parser.c	lib/parser.c: fix up comments for valid return values from match_number	2013-02-21 17:22:25 -08:00
pci_iomap.c
percpu-refcount.c	percpu-refcount: use RCU-sched insted of normal RCU	2013-06-16 16:12:26 -07:00
percpu-rwsem.c	percpu_rw_semaphore: add lockdep annotations	2012-12-17 17:15:18 -08:00
percpu_counter.c	kernel: delete __cpuinit usage from all core kernel files	2013-07-14 19:36:59 -04:00
plist.c
pm-notifier-error-inject.c
prio_heap.c
proportions.c
radix-tree.c
random32.c	prandom: introduce prandom_bytes() and prandom_bytes_state()	2012-12-17 17:15:26 -08:00
ratelimit.c
rational.c
rbtree.c	lib/rbtree.c: avoid the use of non-static __always_inline	2013-01-11 14:54:56 -08:00
rbtree_test.c	rbtree_test: add __init/__exit annotations	2013-04-30 17:04:07 -07:00
reciprocal_div.c
rwsem-spinlock.c	rwsem: simplify __rwsem_do_wake	2013-05-07 07:20:16 -07:00
rwsem.c	rwsem: check counter to avoid cmpxchg calls	2013-05-07 16:11:51 -07:00
scatterlist.c	lib/scatterlist: error handling in __sg_alloc_table()	2013-07-09 10:33:31 -07:00
sha1.c
show_mem.c	mm, show_mem: suppress page counts in non-blockable contexts	2013-04-29 15:54:28 -07:00
smp_processor_id.c
sort.c
spinlock_debug.c
stmp_device.c
string.c
string_helpers.c	lib/string_helpers: introduce generic string_unescape	2013-04-30 17:04:03 -07:00
strncpy_from_user.c
strnlen_user.c
swiotlb.c	x86, kdump: Set crashkernel_low automatically	2013-04-17 12:35:32 -07:00
syscall.c
test-kstrtox.c
test-string_helpers.c	lib/string_helpers: introduce generic string_unescape	2013-04-30 17:04:03 -07:00
textsearch.c
timerqueue.c
ts_bm.c
ts_fsm.c
ts_kmp.c
ucs2_string.c	Move utf16 functions to kernel core and rename	2013-04-15 21:23:03 +01:00
usercopy.c	Kconfig: consolidate CONFIG_DEBUG_STRICT_USER_COPY_CHECKS	2013-04-30 17:04:09 -07:00
uuid.c	uuid: use prandom_bytes()	2013-04-29 18:28:42 -07:00
vsprintf.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next	2013-07-09 18:24:39 -07:00