* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, sparseirq: clean up Kconfig entry
x86: turn CONFIG_SPARSE_IRQ off by default
sparseirq: fix numa_migrate_irq_desc dependency and comments
sparseirq: add kernel-doc notation for new member in irq_desc, -v2
locking, irq: enclose irq_desc_lock_class in CONFIG_LOCKDEP
sparseirq, xen: make sure irq_desc is allocated for interrupts
sparseirq: fix !SMP building, #2
x86, sparseirq: move irq_desc according to smp_affinity, v7
proc: enclose desc variable of show_stat() in CONFIG_SPARSE_IRQ
sparse irqs: add irqnr.h to the user headers list
sparse irqs: handle !GENIRQ platforms
sparseirq: fix !SMP && !PCI_MSI && !HT_IRQ build
sparseirq: fix Alpha build failure
sparseirq: fix typo in !CONFIG_IO_APIC case
x86, MSI: pass irq_cfg and irq_desc
x86: MSI start irq numbering from nr_irqs_gsi
x86: use NR_IRQS_LEGACY
sparse irq_desc[] array: core kernel and x86 changes
genirq: record IRQ_LEVEL in irq_desc[]
irq.h: remove padding from irq_desc on 64bits
Impact: simplify code
commit "08678b0: generic: sparse irqs: use irq_desc() [...]" introduced
the irq_desc_lock_class variable.
But it is used only if CONFIG_SPARSE_IRQ=Y or CONFIG_TRACE_IRQFLAGS=Y.
Otherwise, following warnings happen:
CC kernel/irq/handle.o
kernel/irq/handle.c:26: warning: 'irq_desc_lock_class' defined but not used
Actually, current early_init_irq_lock_class has a bit strange and messy ifdef.
In addition, it is not valueable.
1. this function is protected by !CONFIG_SPARSE_IRQ, but that is not necessary.
if CONFIG_SPARSE_IRQ=Y, desc of all irq number are initialized by NULL
at first - then this function calling is safe.
2. this function protected by CONFIG_TRACE_IRQFLAGS too. but it is not
necessary either, because lockdep_set_class() doesn't have bad side
effect even if CONFIG_TRACE_IRQFLAGS=n.
This patch bloat kernel size a bit on CONFIG_TRACE_IRQFLAGS=n and
CONFIG_SPARSE_IRQ=Y - but that's ok. early_init_irq_lock_class() is not
a fastpatch at all.
To avoid messy ifdefs is more important than a few bytes diet.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: introduce new lockdep API
Allow to change a held lock's class. Basically the same as the existing
code to change a subclass therefore reuse all that.
The XFS code will be able to use this to annotate their inode locking.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
fix this warning:
net/bluetooth/af_bluetooth.c:60: warning: ‘bt_key_strings’ defined but not used
net/bluetooth/af_bluetooth.c:71: warning: ‘bt_slock_key_strings’ defined but not used
this is a lockdep macro problem in the !LOCKDEP case.
We cannot convert it to an inline because the macro works on multiple types,
but we can mark the parameter used.
[ also clean up a misaligned tab in sock_lock_init_class_and_name() ]
[ also remove #ifdefs from around af_family_clock_key strings - which
were certainly added to get rid of the ugly build warnings. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>
fix this warning:
net/bluetooth/af_bluetooth.c:60: warning: ‘bt_key_strings’ defined but not used
net/bluetooth/af_bluetooth.c:71: warning: ‘bt_slock_key_strings’ defined but not used
this is a lockdep macro problem in the !LOCKDEP case.
We cannot convert it to an inline because the macro works on multiple types,
but we can mark the parameter used.
[ also clean up a misaligned tab in sock_lock_init_class_and_name() ]
[ also remove #ifdefs from around af_family_clock_key strings - which
were certainly added to get rid of the ugly build warnings. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We currently only provide points that have to wait on contention, also
lists the points we have to wait for.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
useful to establish a lock dependency in case the actual dependency is
rare or hard to trigger.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
certain configs produce:
[ 70.076229] BUG: MAX_LOCKDEP_KEYS too low!
[ 70.080230] turning off the locking correctness validator.
tune them up.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
There is a overflow by 1 case in the new shrunken hlock code.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
the names were too generic:
drivers/uio/uio.c:87: error: expected identifier or '(' before 'do'
drivers/uio/uio.c:87: error: expected identifier or '(' before 'while'
drivers/uio/uio.c:113: error: 'map_release' undeclared here (not in a function)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Expose the new lock protection lock.
This can be used to annotate places where we take multiple locks of the
same class and avoid deadlocks by always taking another (top-level) lock
first.
NOTE: we're still bound to the MAX_LOCK_DEPTH (48) limit.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
On Fri, 2008-08-01 at 16:26 -0700, Linus Torvalds wrote:
> On Fri, 1 Aug 2008, David Miller wrote:
> >
> > Taking more than a few locks of the same class at once is bad
> > news and it's better to find an alternative method.
>
> It's not always wrong.
>
> If you can guarantee that anybody that takes more than one lock of a
> particular class will always take a single top-level lock _first_, then
> that's all good. You can obviously screw up and take the same lock _twice_
> (which will deadlock), but at least you cannot get into ABBA situations.
>
> So maybe the right thing to do is to just teach lockdep about "lock
> protection locks". That would have solved the multi-queue issues for
> networking too - all the actual network drivers would still have taken
> just their single queue lock, but the one case that needs to take all of
> them would have taken a separate top-level lock first.
>
> Never mind that the multi-queue locks were always taken in the same order:
> it's never wrong to just have some top-level serialization, and anybody
> who needs to take <n> locks might as well do <n+1>, because they sure as
> hell aren't going to be on _any_ fastpaths.
>
> So the simplest solution really sounds like just teaching lockdep about
> that one special case. It's not "nesting" exactly, although it's obviously
> related to it.
Do as Linus suggested. The lock protection lock is called nest_lock.
Note that we still have the MAX_LOCK_DEPTH (48) limit to consider, so anything
that spills that it still up shit creek.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Most the free-standing lock_acquire() usages look remarkably similar, sweep
them into a new helper.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
this can be used to reset a held lock's subclass, for arbitrary-depth
iterated data structures such as trees or lists which have per-node
locks.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When we traverse the graph, either forwards or backwards, we
are interested in whether a certain property exists somewhere
in a node reachable in the graph.
Therefore it is never necessary to traverse through a node more
than once to get a correct answer to the given query.
Take advantage of this property using a global ID counter so that we
need not clear all the markers in all the lock_class entries before
doing a traversal. A new ID is choosen when we start to traverse, and
we continue through a lock_class only if it's ID hasn't been marked
with the new value yet.
This short-circuiting is essential especially for high CPU count
systems. The scheduler has a runqueue per cpu, and needs to take
two runqueue locks at a time, which leads to long chains of
backwards and forwards subgraphs from these runqueue lock nodes.
Without the short-circuit implemented here, a graph traversal on
a runqueue lock can take up to (1 << (N - 1)) checks on a system
with N cpus.
For anything more than 16 cpus or so, lockdep will eventually bring
the machine to a complete standstill.
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
STATIC_LOCKDEP_MAP_INIT is defined twice in lockdep.h. I guess
it's a copy & paste.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch records array of lock_class into lock_chain, and export
lock_chain information via /proc/lockdep_chains.
It is based on x86/master branch of git-x86 tree, and has been tested
on x86_64 platform.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In the following scenario:
code path 1:
my_function() -> lock(L1); ...; flush_workqueue(); ...
code path 2:
run_workqueue() -> my_work() -> ...; lock(L1); ...
you can get a deadlock when my_work() is queued or running
but my_function() has acquired L1 already.
This patch adds a pseudo-lock to each workqueue to make lockdep
warn about this scenario.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Provide a check to validate that we do not hold any locks when switching
back to user-space.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
__acquire
|
lock _____
| \
| __contended
| |
| wait
| _______/
|/
|
__acquired
|
__release
|
unlock
We measure acquisition and contention bouncing.
This is done by recording a cpu stamp in each lock instance.
Contention bouncing requires the cpu stamp to be set on acquisition. Hence we
move __acquired into the generic path.
__acquired is then used to measure acquisition bouncing by comparing the
current cpu with the old stamp before replacing it.
__contended is used to measure contention bouncing (only useful for preemptable
locks)
[akpm@linux-foundation.org: cleanups]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- update the copyright notices
- use the default hash function
- fix a thinko in a BUILD_BUG_ON
- add a WARN_ON to spot inconsitent naming
- fix a termination issue in /proc/lock_stat
[akpm@linux-foundation.org: cleanups]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce the core lock statistics code.
Lock statistics provides lock wait-time and hold-time (as well as the count
of corresponding contention and acquisitions events). Also, the first few
call-sites that encounter contention are tracked.
Lock wait-time is the time spent waiting on the lock. This provides insight
into the locking scheme, that is, a heavily contended lock is indicative of
a too coarse locking scheme.
Lock hold-time is the duration the lock was held, this provides a reference for
the wait-time numbers, so they can be put into perspective.
1)
lock
2)
... do stuff ..
unlock
3)
The time between 1 and 2 is the wait-time. The time between 2 and 3 is the
hold-time.
The lockdep held-lock tracking code is reused, because it already collects locks
into meaningful groups (classes), and because it is an existing infrastructure
for lock instrumentation.
Currently lockdep tracks lock acquisition with two hooks:
lock()
lock_acquire()
_lock()
... code protected by lock ...
unlock()
lock_release()
_unlock()
We need to extend this with two more hooks, in order to measure contention.
lock_contended() - used to measure contention events
lock_acquired() - completion of the contention
These are then placed the following way:
lock()
lock_acquire()
if (!_try_lock())
lock_contended()
_lock()
lock_acquired()
... do locked stuff ...
unlock()
lock_release()
_unlock()
(Note: the try_lock() 'trick' is used to avoid instrumenting all platform
dependent lock primitive implementations.)
It is also possible to toggle the two lockdep features at runtime using:
/proc/sys/kernel/prove_locking
/proc/sys/kernel/lock_stat
(esp. turning off the O(n^2) prove_locking functionaliy can help)
[akpm@linux-foundation.org: build fixes]
[akpm@linux-foundation.org: nuke unneeded ifdefs]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds
KOSAKI Motohiro
Peter Zijlstra
Ingo Molnar
Dave Jones
David Miller
Li Zefan
Huang, Ying
Johannes Berg
Jarek Poplawski