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8acd91e862
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Peter Zijlstra 8acd91e862 locking/lockdep: Revert qrwlock recusive stuff 
Commit f0bab73cb5 ("locking/lockdep: Restrict the use of recursive
read_lock() with qrwlock") changed lockdep to try and conform to the
qrwlock semantics which differ from the traditional rwlock semantics.

In particular qrwlock is fair outside of interrupt context, but in
interrupt context readers will ignore all fairness.

The problem modeling this is that read and write side have different
lock state (interrupts) semantics but we only have a single
representation of these. Therefore lockdep will get confused, thinking
the lock can cause interrupt lock inversions.

So revert it for now; the old rwlock semantics were already imperfectly
modeled and the qrwlock extra won't fit either.

If we want to properly fix this, I think we need to resurrect the work
by Gautham did a few years ago that split the read and write state of
locks:

   http://lwn.net/Articles/332801/

FWIW the locking selftest that would've failed (and was reported by
Borislav earlier) is something like:

  RL(X1);	/* IRQ-ON */
  LOCK(A);
  UNLOCK(A);
  RU(X1);

  IRQ_ENTER();
  RL(X1);	/* IN-IRQ */
  RU(X1);
  IRQ_EXIT();

At which point it would report that because A is an IRQ-unsafe lock we
can suffer the following inversion:

	CPU0		CPU1

	lock(A)
			lock(X1)
			lock(A)
	<IRQ>
	 lock(X1)

And this is 'wrong' because X1 can recurse (assuming the above lock are
in fact read-lock) but lockdep doesn't know about this.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: ego@linux.vnet.ibm.com
Cc: bp@alien8.de
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20140930132600.GA7444@worktop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-03 06:09:30 +02:00
..
fonts partly revert commit 8a10bc9: parisc/sti_console: prefer Linux fonts over built-in ROM fonts 2014-03-23 16:44:42 +01:00
lz4 lz4: add overrun checks to lz4_uncompress_unknownoutputsize() 2014-07-03 16:12:04 -07:00
lzo lzo: properly check for overruns 2014-06-23 14:12:01 -04:00
mpi MPILIB: add module description and license 2013-09-25 17:17:01 +01:00
raid6 md update for v3.12 2013-09-10 13:03:41 -07:00
reed_solomon
xz lib/xz: enable all filters by default in Kconfig 2014-06-04 16:54:18 -07:00
zlib_deflate zlib: slim down zlib_deflate() workspace when possible 2011-03-22 17:44:17 -07:00
zlib_inflate
.gitignore X.509: Implement simple static OID registry 2012-10-08 13:50:18 +10:30
argv_split.c argv_split(): teach it to handle mutable strings 2013-04-29 18:28:19 -07:00
asn1_decoder.c lib/asn1_decoder.c: kernel-doc warning fix 2014-06-04 16:54:19 -07:00
assoc_array.c assoc_array: remove global variable 2014-01-23 09:25:10 -08:00
atomic64_test.c lib/atomic64_test.c: convert printk(KERN_INFO to pr_info 2014-06-04 16:54:19 -07:00
atomic64.c lib: atomic64: Initialize locks statically to fix early users 2012-12-20 13:50:16 -08:00
audit.c audit: Add generic compat syscall support 2014-03-20 10:11:35 -04:00
average.c lib: Ensure EWMA does not store wrong intermediate values 2014-01-16 23:46:06 -08:00
bcd.c usb/core: use bin2bcd() for bcdDevice in RH 2012-09-10 11:13:16 -07:00
bch.c lib: add shared BCH ECC library 2011-03-11 14:25:50 +00:00
bitmap.c propagate name change to comments in kernel source 2012-12-06 10:39:54 +01:00
bitrev.c
bsearch.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
btree.c lib/btree.c: fix leak of whole btree nodes 2014-06-04 16:54:18 -07:00
bug.c lib/bug.c: convert printk to pr_foo() 2014-06-04 16:54:19 -07:00
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 lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
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/clz_ctz.c: add prototype declarations in lib/clz_ctz.c 2014-04-03 16:21:12 -07:00
clz_tab.c lib: Fix multiple definitions of clz_tab 2012-02-02 10:34:23 +11:00
cmdline.c lib/cmdline.c: declare exported symbols immediately 2014-01-23 16:36:57 -08:00
compat_audit.c audit: Add generic compat syscall support 2014-03-20 10:11:35 -04:00
cordic.c Docs: wording: functions -> algorithm 2011-10-29 21:20:22 +02:00
cpu_rmap.c Remove GENERIC_HARDIRQ config option 2013-09-13 15:09:52 +02:00
cpu-notifier-error-inject.c cpu: rewrite cpu-notifier-error-inject module 2012-07-30 17:25:22 -07:00
cpumask.c lib/cpumask: cpumask_set_cpu_local_first to use all cores when numa node is not defined 2014-07-02 18:29:23 -07:00
crc7.c lib/crc7: Shift crc7() output left 1 bit 2014-05-16 14:26:52 -04:00
crc8.c lib: crc8: add new library module providing crc8 algorithm 2011-06-03 15:01:06 -04:00
crc16.c
crc32.c lib/crc32.c: remove unnecessary __constant 2014-06-04 16:54:19 -07:00
crc32defs.h crc32: select an algorithm via Kconfig 2012-03-23 16:58:38 -07:00
crc-ccitt.c
crc-itu-t.c
crc-t10dif.c crypto: crct10dif - Add fallback for broken initrds 2013-09-12 15:31:34 +10:00
ctype.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
debug_locks.c mutex: Add support for wound/wait style locks 2013-06-26 12:10:56 +02:00
debugobjects.c lib/debugobjects.c: convert printk(KERN_DEBUG to pr_debug 2014-06-04 16:53:53 -07:00
dec_and_lock.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
decompress_bunzip2.c decompress_bunzip2: remove invalid vi modeline 2011-12-06 10:00:05 +01:00
decompress_inflate.c lib/decompress_inflate.c: include appropriate header file 2014-04-03 16:21:12 -07:00
decompress_unlz4.c lib/decompress_unlz4.c: always set an error return code on failures 2014-01-23 16:37:04 -08:00
decompress_unlzma.c treewide: Fix comment and string typo 'bufer' 2011-12-06 09:53:40 +01:00
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 Fix common misspellings 2011-03-31 11:26:23 -03:00
decompress.c initramfs: debug detected compression method 2014-04-07 16:36:11 -07:00
devres.c lib/devres.c: fix checkpatch warnings 2014-05-24 07:28:01 +09:00
digsig.c lib/digsig.c: kernel-doc warning fixes 2014-06-04 16:54:19 -07:00
div64.c math64: New separate div64_u64_rem helper 2013-08-23 09:02:14 -04:00
dma-debug.c dma debug: account for cachelines and read-only mappings in overlap tracking 2014-03-04 07:55:47 -08:00
dump_stack.c asmlinkage: Add explicit __visible to drivers/*, lib/*, kernel/* 2014-05-05 16:07:46 -07:00
dynamic_debug.c dynamic_debug: replace obselete simple_strtoul() with kstrtouint() 2014-01-27 21:02:39 -08:00
dynamic_queue_limits.c bql: Avoid possible inconsistent calculation. 2012-05-31 18:18:17 -04:00
earlycpio.c earlycpio.c: Fix the confusing comment of find_cpio_data(). 2013-08-14 23:24:01 +02:00
extable.c
fault-inject.c debugfs: add get/set for atomic types 2013-06-03 13:55:01 -07:00
fdt_empty_tree.c lib: add fdt_empty_tree.c 2014-04-30 19:49:37 +01:00
fdt_ro.c of/lib: Allow scripts/dtc/libfdt to be used from kernel code 2012-07-23 13:54:52 +01:00
fdt_rw.c of/lib: Allow scripts/dtc/libfdt to be used from kernel code 2012-07-23 13:54:52 +01:00
fdt_strerror.c of/lib: Allow scripts/dtc/libfdt to be used from kernel code 2012-07-23 13:54:52 +01:00
fdt_sw.c of/lib: Allow scripts/dtc/libfdt to be used from kernel code 2012-07-23 13:54:52 +01:00
fdt_wip.c of/lib: Allow scripts/dtc/libfdt to be used from kernel code 2012-07-23 13:54:52 +01:00
fdt.c of/lib: Allow scripts/dtc/libfdt to be used from kernel code 2012-07-23 13:54:52 +01:00
find_last_bit.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
find_next_bit.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
flex_array.c reciprocal_divide: update/correction of the algorithm 2014-01-21 23:17:20 -08:00
flex_proportions.c lib/flex_proportions.c: fix corruption of denominator in flexible proportions 2012-09-25 08:59:21 -07:00
gcd.c lib/gcd.c: prevent possible div by 0 2012-10-06 03:04:57 +09:00
gen_crc32table.c sections: fix const sections for crc32 table 2012-10-06 03:04:46 +09:00
genalloc.c lib/genalloc.c: add check gen_pool_dma_alloc() if dma pointer is not NULL 2014-01-29 16:22:39 -08:00
halfmd4.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
hash.c lib: hash: follow-up fixups for arch hash 2013-12-19 00:14:53 -05:00
hexdump.c lib: introduce upper case hex ascii helpers 2013-09-20 15:38:26 -04:00
hweight.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
idr.c idr: reduce the unneeded check in free_layer() 2014-06-06 16:08:12 -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_test.c lib: Export interval_tree 2014-05-05 09:09:14 +02:00
interval_tree.c lib: Export interval_tree 2014-05-05 09:09:14 +02:00
iomap_copy.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
iomap.c Kconfig: rename HAS_IOPORT to HAS_IOPORT_MAP 2014-04-07 16:36:11 -07:00
iommu-helper.c The following text was taken from the original review request: 2012-03-24 10:24:31 -07:00
ioremap.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
iovec.c iovec: move memcpy_from/toiovecend to lib/iovec.c 2014-06-27 11:47:58 -07:00
irq_regs.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
is_single_threaded.c
jedec_ddr_data.c ddr: add LPDDR2 data from JESD209-2 2012-05-02 00:04:06 -07:00
kasprintf.c lib/kasprintf.c: use kmalloc_track_caller() to get accurate traces for kvasprintf 2012-10-11 08:50:15 +09:00
Kconfig lib: Export interval_tree 2014-05-05 09:09:14 +02:00
Kconfig.debug locking/Documentation: Move locking related docs into Documentation/locking/ 2014-08-13 10:32:03 +02:00
Kconfig.kgdb treewide: Fix typo in printk 2013-06-18 13:48:45 +02:00
Kconfig.kmemcheck
kfifo.c kfifo: kfifo_copy_{to,from}_user: fix copied bytes calculation 2013-11-15 09:32:23 +09:00
klist.c klist: del waiter from klist_remove_waiters before wakeup waitting process 2013-05-21 10:16:39 -07:00
kobject_uevent.c kobject: Make support for uevent_helper optional. 2014-04-25 12:00:49 -07:00
kobject.c sysfs, kobject: add sysfs wrapper for kernfs_enable_ns() 2014-02-07 16:08:57 -08:00
kstrtox.c lib/kstrtox.c: remove redundant cleanup 2014-01-23 16:36:57 -08:00
kstrtox.h lib/kstrtox: common code between kstrto*() and simple_strto*() functions 2011-10-31 17:30:56 -07:00
lcm.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
libcrc32c.c lib/libcrc32c.c: use PTR_ERR_OR_ZERO 2014-06-04 16:54:18 -07:00
list_debug.c rcu: Fix broken strings in RCU's source code. 2012-07-06 06:01:49 -07:00
list_sort.c lib/: rename random32() to prandom_u32() 2013-04-29 18:28:42 -07:00
llist.c llists-move-llist_reverse_order-from-raid5-to-llistc-fix 2013-11-15 09:32:22 +09:00
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 locking/lockdep: Revert qrwlock recusive stuff 2014-10-03 06:09:30 +02:00
lockref.c arch, locking: Ciao arch_mutex_cpu_relax() 2014-07-17 12:32:47 +02:00
lru_cache.c lru_cache: introduce lc_get_cumulative() 2013-03-22 22:17:36 -06:00
Makefile Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-06-12 14:27:40 -07:00
md5.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
memory-notifier-error-inject.c memory: memory notifier error injection module 2012-07-30 17:25:22 -07:00
memweight.c string: introduce memweight() 2012-07-30 17:25:16 -07:00
net_utils.c net: core: move mac_pton() to lib/net_utils.c 2013-06-05 12:00:27 -07:00
nlattr.c Merge branch 'next' (accumulated 3.16 merge window patches) into master 2014-06-08 11:31:16 -07:00
notifier-error-inject.c mode_t, whack-a-mole at 11... 2013-04-09 14:13:05 -04:00
notifier-error-inject.h fault-injection: notifier error injection 2012-07-30 17:25:22 -07:00
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: put EXPORT_SYMBOLs in the conventional place 2014-01-23 16:36:55 -08:00
pci_iomap.c lib: add NO_GENERIC_PCI_IOPORT_MAP 2012-01-31 23:19:47 +02:00
percpu_counter.c lib/percpu_counter.c: fix bad percpu counter state during suspend 2014-04-08 16:48:51 -07:00
percpu_ida.c Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2014-02-14 10:45:18 -08:00
percpu_test.c percpu: add test module for various percpu operations 2013-11-13 12:09:11 +09:00
percpu-refcount.c percpu-refcount: implement percpu_ref_reinit() and percpu_ref_is_zero() 2014-06-28 08:10:14 -04:00
plist.c lib/plist.c: replace pr_debug with printk in plist_test() 2014-06-04 16:54:18 -07:00
pm-notifier-error-inject.c PM: PM notifier error injection module 2012-07-30 17:25:22 -07:00
prio_heap.c
proportions.c locking, lib/proportions: Annotate prop_local_percpu::lock as raw 2011-09-13 11:11:50 +02:00
radix-tree.c lib/radix-tree.c: update the kmemleak stack trace for radix tree allocations 2014-06-06 16:08:17 -07:00
random32.c lib/random32.c: minor cleanups and kdoc fix 2014-04-03 16:21:11 -07:00
ratelimit.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
rational.c lib: Change mail address of Oskar Schirmer 2012-05-17 15:18:37 +02:00
rbtree_test.c rbtree/test: test rbtree_postorder_for_each_entry_safe() 2014-01-23 16:37:03 -08:00
rbtree.c rbtree: add postorder iteration functions 2013-09-11 15:59:19 -07:00
reciprocal_div.c reciprocal_divide: update/correction of the algorithm 2014-01-21 23:17:20 -08:00
scatterlist.c lib/scatterlist: export sg_miter_skip() 2013-12-08 17:56:37 -08:00
sha1.c lib: reduce the use of module.h wherever possible 2012-03-07 15:04:04 -05:00
show_mem.c lib/show_mem.c: show num_poisoned_pages when oom 2014-01-21 16:19:48 -08:00
smp_processor_id.c percpu: add preemption checks to __this_cpu ops 2014-04-07 16:36:14 -07:00
sort.c
stmp_device.c lib: add support for stmp-style devices 2012-04-20 23:27:08 +02:00
string_helpers.c lib/string_helpers: introduce generic string_unescape 2013-04-30 17:04:03 -07:00
string.c lib/string.c: use the name "C-string" in comments 2014-06-04 16:54:18 -07:00
strncpy_from_user.c word-at-a-time: make the interfaces truly generic 2012-05-26 11:33:40 -07:00
strnlen_user.c lib: Fix generic strnlen_user for 32-bit big-endian machines 2012-05-27 20:59:46 -07:00
swiotlb.c swiotlb: don't assume PA 0 is invalid 2014-06-20 16:04:32 -04:00
syscall.c lib/syscall.c: unexport task_current_syscall() 2014-04-03 16:21:06 -07:00
test_bpf.c net: filter: fix nlattr and nlattr_nest BPF tests 2014-06-11 00:13:16 -07:00
test_module.c test: add minimal module for verification testing 2014-01-23 16:36:57 -08:00
test_user_copy.c test: check copy_to/from_user boundary validation 2014-01-23 16:36:57 -08:00
test-kstrtox.c lib/test-kstrtox.c: mark const init data with __initconst instead of __initdata 2012-05-29 16:22:32 -07:00
test-string_helpers.c lib/string_helpers: introduce generic string_unescape 2013-04-30 17:04:03 -07:00
textsearch.c lib/textsearch.c: move EXPORT_SYMBOL after functions 2014-06-04 16:54:19 -07:00
timerqueue.c The following text was taken from the original review request: 2012-03-24 10:24:31 -07:00
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 lib/vsprintf.c: fix comparison to bool 2014-06-04 16:54:18 -07:00