12 Oct, 2007
2 commits
-
Provide a check to validate that we do not hold any locks when switching
back to user-space.Signed-off-by: Peter Zijlstra
Signed-off-by: Ingo Molnar -
It is possible for the current->curr_chain_key to become inconsistent with the
current index if the chain fails to validate. The end result is that future
lock_acquire() operations may inadvertently fail to find a hit in the cache
resulting in a new node being added to the graph for every acquire.Signed-off-by: Gregory Haskins
Signed-off-by: Peter Zijlstra
Signed-off-by: Ingo Molnar
20 Jul, 2007
7 commits
-
When I started adding support for lockdep to 64-bit powerpc, I got a
lockdep_init_error and with this patch was able to pinpoint why and where
to put lockdep_init(). Let's support this generally for others adding
lockdep support to their architecture.Signed-off-by: Johannes Berg
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Arjan van de Ven
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
__acquire
|
lock _____
| \
| __contended
| |
| wait
| _______/
|/
|
__acquired
|
__release
|
unlockWe 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
Acked-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
- 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
Acked-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Present all this fancy new lock statistics information:
*warning, _wide_ output ahead*
(output edited for purpose of brevity)
# cat /proc/lock_stat
lock_stat version 0.1
-----------------------------------------------------------------------------------------------------------------------------------------------------------------
class name contentions waittime-min waittime-max waittime-total acquisitions holdtime-min holdtime-max holdtime-total
-----------------------------------------------------------------------------------------------------------------------------------------------------------------&inode->i_mutex: 14458 6.57 398832.75 2469412.23 6768876 0.34 11398383.65 339410830.89
---------------
&inode->i_mutex 4486 [] pipe_wait+0x86/0x8d
&inode->i_mutex 0 [] pipe_write_fasync+0x29/0x5d
&inode->i_mutex 0 [] pipe_read+0x74/0x3a5
&inode->i_mutex 0 [] do_lookup+0x81/0x1ae.................................................................................................................................................................
&inode->i_data.tree_lock-W: 491 0.27 62.47 493.89 2477833 0.39 468.89 1146584.25
&inode->i_data.tree_lock-R: 65 0.44 4.27 48.78 26288792 0.36 184.62 10197458.24
--------------------------
&inode->i_data.tree_lock 46 [] __do_page_cache_readahead+0x69/0x24f
&inode->i_data.tree_lock 31 [] add_to_page_cache+0x31/0xba
&inode->i_data.tree_lock 0 [] __do_page_cache_readahead+0xc2/0x24f
&inode->i_data.tree_lock 0 [] find_get_page+0x1a/0x58.................................................................................................................................................................
proc_inum_idr.lock: 0 0.00 0.00 0.00 36 0.00 65.60 148.26
proc_subdir_lock: 0 0.00 0.00 0.00 3049859 0.00 106.81 1563212.42
shrinker_rwsem-W: 0 0.00 0.00 0.00 5 0.00 1.73 3.68
shrinker_rwsem-R: 0 0.00 0.00 0.00 633 2.57 246.57 10909.76'contentions' and 'acquisitions' are the number of such events measured (since
the last reset). The waittime- and holdtime- (min, max, total) numbers are
presented in microseconds.If there are any contention points, the lock class is presented in the block
format (as i_mutex and tree_lock above), otherwise a single line of output is
presented.The output is sorted on absolute number of contentions (read + write), this
should get the worst offenders presented first, so that:# grep : /proc/lock_stat | head
will quickly show who's bad.
The stats can be reset using:
# echo 0 > /proc/lock_stat
[bunk@stusta.de: make 2 functions static]
[akpm@linux-foundation.org: fix printk warning]
Signed-off-by: Peter Zijlstra
Acked-by: Ingo Molnar
Acked-by: Jason Baron
Signed-off-by: Adrian Bunk
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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 contentionThese 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
Acked-by: Ingo Molnar
Acked-by: Jason Baron
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Move code around to get fewer but larger #ifdef sections. Break some
in-function #ifdefs out into their own functions.Signed-off-by: Peter Zijlstra
Acked-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Ensure that all of the lock dependency tracking code is under
CONFIG_PROVE_LOCKING. This allows us to use the held lock tracking code for
other purposes.Signed-off-by: Peter Zijlstra
Acked-by: Ingo Molnar
Acked-by: Jason Baron
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
18 Jul, 2007
1 commit
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KSYM_NAME_LEN is peculiar in that it does not include the space for the
trailing '\0', forcing all users to use KSYM_NAME_LEN + 1 when allocating
buffer. This is nonsense and error-prone. Moreover, when the caller
forgets that it's very likely to subtly bite back by corrupting the stack
because the last position of the buffer is always cleared to zero.This patch increments KSYM_NAME_LEN by one and updates code accordingly.
* off-by-one bug in asm-powerpc/kprobes.h::kprobe_lookup_name() macro
is fixed.* Where MODULE_NAME_LEN and KSYM_NAME_LEN were used together,
MODULE_NAME_LEN was treated as if it didn't include space for the
trailing '\0'. Fix it.Signed-off-by: Tejun Heo
Acked-by: Paulo Marques
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 May, 2007
4 commits
-
It looks like a remainder from designing...
Signed-off-by: Jarek Poplawski
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Signed-off-by: Jarek Poplawski
Acked-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Several kallsyms_lookup() pass dummy arguments but only need, say, module's
name. Make kallsyms_lookup() accept NULLs where possible.Also, makes picture clearer about what interfaces are needed for all symbol
resolving business.Signed-off-by: Alexey Dobriyan
Cc: Rusty Russell
Acked-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Simplify the stacktrace code:
- remove the unused task argument to save_stack_trace, it's always
current
- remove the all_contexts flag, it's alwasy 0Signed-off-by: Christoph Hellwig
Cc: Paul Mundt
Cc: Ralf Baechle
Cc: Martin Schwidefsky
Cc: "David S. Miller"
Cc: Andi Kleen
Cc: Akinobu Mita
Acked-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
23 Mar, 2007
1 commit
-
lockdep's data shouldn't be used when debug_locks == 0 because it's not
updated after this, so it's more misleading than helpful.PS: probably lockdep's current-> fields should be reset after it turns
debug_locks off: so, after printing a bug report, but before return from
exported functions, but there are really a lot of these possibilities (e.g.
after DEBUG_LOCKS_WARN_ON), so, something could be missed. (Of course
direct use of this fields isn't recommended either.)Reported-by: Folkert van Heusden
Inspired-by: Oleg Nesterov
Signed-off-by: Jarek Poplawski
Acked-by: Peter Zijlstra
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
02 Mar, 2007
1 commit
-
lockdep_init() is marked __init but used in several places
outside __init code. This causes following warnings:
$ scripts/mod/modpost kernel/lockdep.o
WARNING: kernel/built-in.o - Section mismatch: reference to .init.text:lockdep_init from .text.lockdep_init_map after 'lockdep_init_map' (at offset 0x105)
WARNING: kernel/built-in.o - Section mismatch: reference to .init.text:lockdep_init from .text.lockdep_reset_lock after 'lockdep_reset_lock' (at offset 0x35)
WARNING: kernel/built-in.o - Section mismatch: reference to .init.text:lockdep_init from .text.__lock_acquire after '__lock_acquire' (at offset 0xb2)The warnings are less obviously due to heavy inlining by gcc - this is not
altered.Fix the section mismatch warnings by removing the __init marking, which
seems obviously wrong.Signed-off-by: Sam Ravnborg
Acked-by: Ingo Molnar
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
21 Feb, 2007
1 commit
-
In __lock_acquire check_chain_key can turn off debug_locks, so check is
needed to assure proper return code.Signed-off-by: Jarek Poplawski
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Feb, 2007
2 commits
-
Generate locking graph information into /proc/lockdep, for lock hierarchy
documentation and visualization purposes.sample output:
c089fd5c OPS: 138 FD: 14 BD: 1 --..: &tty->termios_mutex
-> [c07a3430] tty_ldisc_lock
-> [c07a37f0] &port_lock_key
-> [c07afdc0] &rq->rq_lock_key#2The lock classes listed are all the first-hop lock dependencies that
lockdep has seen so far.Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
- returns after DEBUG_LOCKS_WARN_ON added in 3 places
- debug_locks checking after lookup_chain_cache() added in
__lock_acquire()- locking for testing and changing global variable max_lockdep_depth
added in __lock_acquire()From: Ingo Molnar
My __acquire_lock() cleanup introduced a locking bug: on SMP systems we'd
release a non-owned graph lock. Fix this by moving the graph unlock back,
and by leaving the max_lockdep_depth variable update possibly racy. (we
dont care, it's just statistics)Also add some minimal debugging code to graph_unlock()/graph_lock(),
which caught this locking bug.Signed-off-by: Jarek Poplawski
Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
31 Dec, 2006
1 commit
-
kernel/lockdep.c: In function `lookup_chain_cache':
kernel/lockdep.c:1339: warning: long long unsigned int format, u64 arg (arg 2)
kernel/lockdep.c:1344: warning: long long unsigned int format, u64 arg (arg 2)Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
14 Dec, 2006
7 commits
-
Jarek Poplawski noticed that lockdep global state could be accessed in a
racy way if one CPU did a lockdep assert (shutting lockdep down), while the
other CPU would try to do something that changes its global state.This patch fixes those races and cleans up lockdep's internal locking by
adding a graph_lock()/graph_unlock()/debug_locks_off_graph_unlock helpers.(Also note that as we all know the Linux kernel is, by definition, bug-free
and perfect, so this code never triggers, so these fixes are highly
theoretical. I wrote this patch for aesthetic reasons alone.)[akpm@osdl.org: build fix]
[jarkao2@o2.pl: build fix's refix]
Signed-off-by: Ingo Molnar
Signed-off-by: Jarek Poplawski
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
When we print an assert due to scheduling-in-atomic bugs, and if lockdep
is enabled, then the IRQ tracing information of lockdep can be printed
to pinpoint the code location that disabled interrupts. This saved me
quite a bit of debugging time in cases where the backtrace did not
identify the irq-disabling site well enough.Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
CONFIG_DEBUG_LOCKDEP is unacceptably slow because it does not utilize
the chain-hash. Turn the chain-hash back on in this case too.Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Cleanup: the VERY_VERBOSE define was unnecessarily dependent on #ifdef VERBOSE
- while the VERBOSE switch is 0 or 1 (always defined).Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Clear all the chains during lockdep_reset(). This fixes some locking-selftest
false positives i saw on -rt. (never saw those on mainline though, but it
could happen.)Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Make verbose lockdep messages (off by default) more informative by printing
out the hash chain key. (this patch was what helped me catch the earlier
lockdep hash-collision bug)Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fix typo in the class_filter() function. (filtering is not used by default so
this only affects lockdep-internal debugging cases)Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
08 Dec, 2006
6 commits
-
* 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6: (156 commits)
[PATCH] x86-64: Export smp_call_function_single
[PATCH] i386: Clean up smp_tune_scheduling()
[PATCH] unwinder: move .eh_frame to RODATA
[PATCH] unwinder: fully support linker generated .eh_frame_hdr section
[PATCH] x86-64: don't use set_irq_regs()
[PATCH] x86-64: check vector in setup_ioapic_dest to verify if need setup_IO_APIC_irq
[PATCH] x86-64: Make ix86 default to HIGHMEM4G instead of NOHIGHMEM
[PATCH] i386: replace kmalloc+memset with kzalloc
[PATCH] x86-64: remove remaining pc98 code
[PATCH] x86-64: remove unused variable
[PATCH] x86-64: Fix constraints in atomic_add_return()
[PATCH] x86-64: fix asm constraints in i386 atomic_add_return
[PATCH] x86-64: Correct documentation for bzImage protocol v2.05
[PATCH] x86-64: replace kmalloc+memset with kzalloc in MTRR code
[PATCH] x86-64: Fix numaq build error
[PATCH] x86-64: include/asm-x86_64/cpufeature.h isn't a userspace header
[PATCH] unwinder: Add debugging output to the Dwarf2 unwinder
[PATCH] x86-64: Clarify error message in GART code
[PATCH] x86-64: Fix interrupt race in idle callback (3rd try)
[PATCH] x86-64: Remove unwind stack pointer alignment forcing again
...Fixed conflict in include/linux/uaccess.h manually
Signed-off-by: Linus Torvalds
-
The hash_lock must only ever be taken with irqs disabled. This happens in
all the important places, except one codepath: register_lock_class(). The
race should trigger rarely because register_lock_class() is quite rare and
single-threaded (happens during init most of the time).The fix is to disable irqs.
( bug found live in -rt: there preemption is alot more agressive and
preempting with the hash-lock held caused a lockup.)Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Remove the no longer used lockdep_internal().
Signed-off-by: Adrian Bunk
Acked-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
- numeric string size replaced with constant in print_lock_name and
print_lockdep_cache,- return on null pointer in print_lock_dependencies,
- one more lockdep return with 0 with unlocking fix in mark_lock.
Signed-off-by: Jarek Poplawski
Acked-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Here are mainly some lockdep returns with 0 with unlocking fixes.
Signed-off-by: Jarek Poplawski
Signed-off-by: Andrew Morton
Signed-off-by: Ingo Molnar
Signed-off-by: Linus Torvalds -
Stick NFS sockets in their own class to avoid some lockdep warnings. NFS
sockets are never exposed to user-space, and will hence not trigger certain
code paths that would otherwise pose deadlock scenarios.[akpm@osdl.org: cleanups]
Signed-off-by: Peter Zijlstra
Signed-off-by: Steven Dickson
Acked-by: Ingo Molnar
Cc: Trond Myklebust
Acked-by: Neil Brown
Cc: "David S. Miller"
Signed-off-by: Andrew Morton
[ Fixed patch corruption by quilt, pointed out by Peter Zijlstra ]
Signed-off-by: Linus Torvalds
07 Dec, 2006
1 commit
-
Shouldn't be needed anymore since __kernel_text_address
is used unconditionally on x86-64Signed-off-by: Andi Kleen
18 Nov, 2006
1 commit
-
lockdep got confused by certain locks in modules:
INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.Call Trace:
[] dump_trace+0xaa/0x3f2
[] show_trace+0x3a/0x60
[] dump_stack+0x15/0x17
[] __lock_acquire+0x724/0x9bb
[] lock_acquire+0x4d/0x67
[] rt_spin_lock+0x3d/0x41
[] :ip_conntrack:__ip_ct_refresh_acct+0x131/0x174
[] :ip_conntrack:udp_packet+0xbf/0xcf
[] :ip_conntrack:ip_conntrack_in+0x394/0x4a7
[] nf_iterate+0x41/0x7f
[] nf_hook_slow+0x64/0xd5
[] ip_rcv+0x24e/0x506
[...]Steven Rostedt found the bug: static_obj() check did not take
PERCPU_ENOUGH_ROOM into account, so in-module DEFINE_PER_CPU-area locks
were triggering this message.Signed-off-by: Ingo Molnar
Signed-off-by: Steven Rostedt
Signed-off-by: Linus Torvalds
17 Oct, 2006
2 commits
-
* git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: fm801-gp - handle errors from pci_enable_device()
Input: gameport core - handle errors returned by device_bind_driver()
Input: serio core - handle errors returned by device_bind_driver()
Lockdep: fix compile error in drivers/input/serio/serio.c
Input: serio - add lockdep annotations
Lockdep: add lockdep_set_class_and_subclass() and lockdep_set_subclass()
Input: atkbd - supress "too many keys" error message
Input: i8042 - supress ACK/NAKs when blinking during panic
Input: add missing exports to fix modular build -
In general, lockdep warnings are intended to be non-fatal, so I have put in
various practical limits on internal data structure failure modes. We haven't
had a /single/ lockdep-internal crash ever since lockdep went upstream [the
unwinder crashes are outside of lockdep], and that's largely due to the good
internal checks it does.Recursion within the dependency graph is currently limited to 20, that's
probably not enough on some many-CPU boxes - this patch doubles it to 40. I
have written the lockdep functions to have as small stackframes as possible,
so 40 should be OK too. (The practical recursion limit should be somewhere
between 100 and 200 entries. If we hit that then I'll change the algorithm to
be iteration-based. Graph walking logic is so easy to program via recursion,
so i'd like to keep recursion as long as possible.)Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Oct, 2006
1 commit
-
Signed-off-by: Alexey Dobriyan
Acked-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Oct, 2006
1 commit
-
This annotation makes it possible to assign a subclass on lock init. This
annotation is meant to reduce the _nested() annotations by assigning a
default subclass.One could do without this annotation and rely on lockdep_set_class()
exclusively, but that would require a manual stack of struct lock_class_key
objects.Signed-off-by: Peter Zijlstra
Signed-off-by: Dmitry Torokhov
02 Oct, 2006
1 commit
-
In some places, particularly drivers and __init code, the init utsns is the
appropriate one to use. This patch replaces those with a the init_utsname
helper.Changes: Removed several uses of init_utsname(). Hope I picked all the
right ones in net/ipv4/ipconfig.c. These are now changed to
utsname() (the per-process namespace utsname) in the previous
patch (2/7)[akpm@osdl.org: CIFS fix]
Signed-off-by: Serge E. Hallyn
Cc: Kirill Korotaev
Cc: "Eric W. Biederman"
Cc: Herbert Poetzl
Cc: Andrey Savochkin
Cc: Serge Hallyn
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
