Introduce DEBUG_LOCKING_API_SELFTESTS, which uses the generic lock debugging
code's silent-failure feature to run a matrix of testcases. There are 210
testcases currently:
+-----------------------
| Locking API testsuite:
+------------------------------+------+------+------+------+------+------+
| spin |wlock |rlock |mutex | wsem | rsem |
-------------------------------+------+------+------+------+------+------+
A-A deadlock: ok | ok | ok | ok | ok | ok |
A-B-B-A deadlock: ok | ok | ok | ok | ok | ok |
A-B-B-C-C-A deadlock: ok | ok | ok | ok | ok | ok |
A-B-C-A-B-C deadlock: ok | ok | ok | ok | ok | ok |
A-B-B-C-C-D-D-A deadlock: ok | ok | ok | ok | ok | ok |
A-B-C-D-B-D-D-A deadlock: ok | ok | ok | ok | ok | ok |
A-B-C-D-B-C-D-A deadlock: ok | ok | ok | ok | ok | ok |
double unlock: ok | ok | ok | ok | ok | ok |
bad unlock order: ok | ok | ok | ok | ok | ok |
--------------------------------------+------+------+------+------+------+
recursive read-lock: | ok | | ok |
--------------------------------------+------+------+------+------+------+
non-nested unlock: ok | ok | ok | ok |
--------------------------------------+------+------+------+
hard-irqs-on + irq-safe-A/12: ok | ok | ok |
soft-irqs-on + irq-safe-A/12: ok | ok | ok |
hard-irqs-on + irq-safe-A/21: ok | ok | ok |
soft-irqs-on + irq-safe-A/21: ok | ok | ok |
sirq-safe-A => hirqs-on/12: ok | ok | ok |
sirq-safe-A => hirqs-on/21: ok | ok | ok |
hard-safe-A + irqs-on/12: ok | ok | ok |
soft-safe-A + irqs-on/12: ok | ok | ok |
hard-safe-A + irqs-on/21: ok | ok | ok |
soft-safe-A + irqs-on/21: ok | ok | ok |
hard-safe-A + unsafe-B #1/123: ok | ok | ok |
soft-safe-A + unsafe-B #1/123: ok | ok | ok |
hard-safe-A + unsafe-B #1/132: ok | ok | ok |
soft-safe-A + unsafe-B #1/132: ok | ok | ok |
hard-safe-A + unsafe-B #1/213: ok | ok | ok |
soft-safe-A + unsafe-B #1/213: ok | ok | ok |
hard-safe-A + unsafe-B #1/231: ok | ok | ok |
soft-safe-A + unsafe-B #1/231: ok | ok | ok |
hard-safe-A + unsafe-B #1/312: ok | ok | ok |
soft-safe-A + unsafe-B #1/312: ok | ok | ok |
hard-safe-A + unsafe-B #1/321: ok | ok | ok |
soft-safe-A + unsafe-B #1/321: ok | ok | ok |
hard-safe-A + unsafe-B #2/123: ok | ok | ok |
soft-safe-A + unsafe-B #2/123: ok | ok | ok |
hard-safe-A + unsafe-B #2/132: ok | ok | ok |
soft-safe-A + unsafe-B #2/132: ok | ok | ok |
hard-safe-A + unsafe-B #2/213: ok | ok | ok |
soft-safe-A + unsafe-B #2/213: ok | ok | ok |
hard-safe-A + unsafe-B #2/231: ok | ok | ok |
soft-safe-A + unsafe-B #2/231: ok | ok | ok |
hard-safe-A + unsafe-B #2/312: ok | ok | ok |
soft-safe-A + unsafe-B #2/312: ok | ok | ok |
hard-safe-A + unsafe-B #2/321: ok | ok | ok |
soft-safe-A + unsafe-B #2/321: ok | ok | ok |
hard-irq lock-inversion/123: ok | ok | ok |
soft-irq lock-inversion/123: ok | ok | ok |
hard-irq lock-inversion/132: ok | ok | ok |
soft-irq lock-inversion/132: ok | ok | ok |
hard-irq lock-inversion/213: ok | ok | ok |
soft-irq lock-inversion/213: ok | ok | ok |
hard-irq lock-inversion/231: ok | ok | ok |
soft-irq lock-inversion/231: ok | ok | ok |
hard-irq lock-inversion/312: ok | ok | ok |
soft-irq lock-inversion/312: ok | ok | ok |
hard-irq lock-inversion/321: ok | ok | ok |
soft-irq lock-inversion/321: ok | ok | ok |
hard-irq read-recursion/123: ok |
soft-irq read-recursion/123: ok |
hard-irq read-recursion/132: ok |
soft-irq read-recursion/132: ok |
hard-irq read-recursion/213: ok |
soft-irq read-recursion/213: ok |
hard-irq read-recursion/231: ok |
soft-irq read-recursion/231: ok |
hard-irq read-recursion/312: ok |
soft-irq read-recursion/312: ok |
hard-irq read-recursion/321: ok |
soft-irq read-recursion/321: ok |
--------------------------------+-----+----------------
Good, all 210 testcases passed! |
--------------------------------+
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
CONFIG_FRAME_POINTER support for s390.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Framework to generate and save stacktraces quickly, without printing anything
to the console.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Generic lock debugging:
- generalized lock debugging framework. For example, a bug in one lock
subsystem turns off debugging in all lock subsystems.
- got rid of the caller address passing (__IP__/__IP_DECL__/etc.) from
the mutex/rtmutex debugging code: it caused way too much prototype
hackery, and lockdep will give the same information anyway.
- ability to do silent tests
- check lock freeing in vfree too.
- more finegrained debugging options, to allow distributions to
turn off more expensive debugging features.
There's no separate 'held mutexes' list anymore - but there's a 'held locks'
stack within lockdep, which unifies deadlock detection across all lock
classes. (this is independent of the lockdep validation stuff - lockdep first
checks whether we are holding a lock already)
Here are the current debugging options:
CONFIG_DEBUG_MUTEXES=y
CONFIG_DEBUG_LOCK_ALLOC=y
which do:
config DEBUG_MUTEXES
bool "Mutex debugging, basic checks"
config DEBUG_LOCK_ALLOC
bool "Detect incorrect freeing of live mutexes"
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
With the lock validator we detect mutex deadlocks (and more), the mutex
deadlock checking code is both redundant and slower. So remove it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The recent vsnprintf() fix introduced an off-by-one, and it's now
possible to overrun the target buffer by one byte.
The "end" pointer points to past the end of the buffer, so if we
have to truncate the result, it needs to be done though "end[-1]".
[ This is just an alternate and simpler patch to one proposed by Andrew
and Jeremy, who actually noticed the problem ]
Acked-by: Andrew Morton <akpm@osdl.org>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Temporarily add EXPORT_UNUSED_SYMBOL and EXPORT_UNUSED_SYMBOL_GPL. These
will be used as a transition measure for symbols that aren't used in the
kernel and are on the way out. When a module uses such a symbol, a warning
is printk'd at modprobe time.
The main reason for removing unused exports is size: eacho export takes
roughly between 100 and 150 bytes of kernel space in the binary. This
patch gives users the option to immediately get this size gain via a config
option.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
RT-mutex tester: scriptable tester for rt mutexes, which allows userspace
scripting of mutex unit-tests (and dynamic tests as well), using the actual
rt-mutex implementation of the kernel.
[akpm@osdl.org: fixlet]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Runtime debugging functionality for rt-mutexes.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add the priority-sorted list (plist) implementation.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Fix function definitions to be ANSI-compliant:
lib/zlib_inflate/inffast.c:68:1: warning: non-ANSI definition of function 'inflate_fast'
lib/zlib_inflate/inftrees.c:33:1: warning: non-ANSI definition of function 'zlib_inflate_table'
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
so that userspace can be notified of dock and undock events.
Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
These are the i386-specific pieces to enable reliable stack traces. This is
going to be even more useful once CFI annotations get added to he assembly
code, namely to entry.S.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
These are the x86_64-specific pieces to enable reliable stack traces. The
only restriction with this is that it currently cannot unwind across the
interrupt->normal stack boundary, as that transition is lacking proper
annotation.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
These are the generic bits needed to enable reliable stack traces based
on Dwarf2-like (.eh_frame) unwind information. Subsequent patches will
enable x86-64 and i386 to make use of this.
Thanks to Andi Kleen and Ingo Molnar, who pointed out several possibilities
for improvement.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch adds idr_replace() to replace an existing pointer in a single
operation.
Device-mapper will use this to update the pointer it stored against a given
id.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The place in the documentation of the Linux kernel to acknowledge
contributions is the CREDITS file.
Give Mark Adler an entry there instead of including a string in the
kernel image.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Implement kasprintf, a kernel version of asprintf. This allocates the
memory required for the formatted string, including the trailing '\0'.
Returns NULL on allocation failure.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This change allows callers to use a 0-byte buffer and a NULL buffer pointer
with vsnprintf, so it can be used to determine how large the resulting
formatted string will be.
Previously the code effectively treated a size of 0 as a size of 4G (on
32-bit systems), with other checks preventing it from actually trying to
emit the string - but the terminal \0 would still be written, which would
crash if the buffer is NULL.
This change changes the boundary check so that 'end' points to the putative
location of the terminal '\0', which is only written if size > 0.
vsnprintf still allows the buffer size to be set very large, to allow
unbounded buffer sizes (to implement sprintf, etc).
[akpm@osdl.org: fix long-vs-longlong confusion]
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Make kernel-doc corrections & additions to lib/crc*.c. Add crc functions to
kernel-api.tmpl in DocBook.
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Make corrections/fixes to kernel-doc in lib/bitmap.c and include it in DocBook
template.
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
In radix_tree_tag_get(), return normalized value of 0/1, as indicated
by its comment.
Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add a new strstrip() function to lib/string.c for removing leading and
trailing whitespace from a string.
Cc: Michael Holzheu <holzheu@de.ibm.com>
Acked-by: Ingo Oeser <ioe-lkml@rameria.de>
Acked-by: Joern Engel <joern@wohnheim.fh-wedel.de>
Cc: Corey Minyard <minyard@acm.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Michael Holzheu <HOLZHEU@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The percpu counter data type are changed in this set of patches to support
more users like ext3 who need more than 32 bit to store the free blocks
total in the filesystem.
- Generic perpcu counters data type changes. The size of the global counter
and local counter were explictly specified using s64 and s32. The global
counter is changed from long to s64, while the local counter is changed from
long to s32, so we could avoid doing 64 bit update in most cases.
- Users of the percpu counters are updated to make use of the new
percpu_counter_init() routine now taking an additional parameter to allow
users to pass the initial value of the global counter.
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The comment states: 'Setting a tag on a not-present item is a BUG.' Hence
if 'index' is larger than the maxindex; the item _cannot_ be presen; it
should also be a BUG.
Also, this allows the following statement (assume a fresh tree):
radix_tree_tag_set(root, 16, 1);
to fail silently, but when preceded by:
radix_tree_insert(root, 32, item);
it would BUG, because the height has been extended by the insert.
In neither case was 16 present.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Reduce radix tree node memory usage by about a factor of 4 for small files
(< 64K). There are pointer traversal and memory usage costs for large
files with dense pagecache.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The ability to have height 0 radix trees (a direct pointer to the data item
rather than going through a full node->slot) quietly disappeared with
old-2.6-bkcvs commit ffee171812d51652f9ba284302d9e5c5cc14bdfd. On 64-bit
machines this causes nearly 600 bytes to be used for every <= 4K file in
pagecache.
Re-introduce this feature, root tags stored in spare ->gfp_mask bits.
Simplify radix_tree_delete's complex tag clearing arrangement (which would
become even more complex) by just falling back to tag clearing functions
(the pagecache radix-tree never uses this path anyway, so the icache
savings will mean it's actually a speedup).
On my 4GB G5, this saves 8MB RAM per kernel kernel source+object tree in
pagecache.
Pagecache lookup, insertion, and removal speed for small files will also be
improved.
This makes RCU radix tree harder, but it's worth it.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Modify the gen_pool allocator (lib/genalloc.c) to utilize a bitmap scheme
instead of the buddy scheme. The purpose of this change is to eliminate
the touching of the actual memory being allocated.
Since the change modifies the interface, a change to the uncached allocator
(arch/ia64/kernel/uncached.c) is also required.
Both Andrey Volkov and Jes Sorenson have expressed a desire that the
gen_pool allocator not write to the memory being managed. See the
following:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113518602713125&w=2http://marc.theaimsgroup.com/?l=linux-kernel&m=113533568827916&w=2
Signed-off-by: Dean Nelson <dcn@sgi.com>
Cc: Andrey Volkov <avolkov@varma-el.com>
Acked-by: Jes Sorensen <jes@trained-monkey.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Upgrade the zlib_inflate implementation in the kernel from a patched
version 1.1.3/4 to a patched 1.2.3.
The code in the kernel is about seven years old and I noticed that the
external zlib library's inflate performance was significantly faster (~50%)
than the code in the kernel on ARM (and faster again on x86_32).
For comparison the newer deflate code is 20% slower on ARM and 50% slower
on x86_32 but gives an approx 1% compression ratio improvement. I don't
consider this to be an improvement for kernel use so have no plans to
change the zlib_deflate code.
Various changes have been made to the zlib code in the kernel, the most
significant being the extra functions/flush option used by ppp_deflate.
This update reimplements the features PPP needs to ensure it continues to
work.
This code has been tested on ARM under both JFFS2 (with zlib compression
enabled) and ppp_deflate and on x86_32. JFFS2 sees an approx. 10% real
world file read speed improvement.
This patch also removes ZLIB_VERSION as it no longer has a correct value.
We don't need version checks anyway as the kernel's module handling will
take care of that for us. This removal is also more in keeping with the
zlib author's wishes (http://www.zlib.net/zlib_faq.html#faq24) and I've
added something to the zlib.h header to note its a modified version.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Joern Engel <joern@wh.fh-wedel.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Introduce __iowrite64_copy. It will be used by the Myri-10G Ethernet
driver to post requests to the NIC. This driver will be submitted soon.
__iowrite64_copy copies to I/O memory in units of 64 bits when possible (on
64 bit architectures). It reverts to __iowrite32_copy on 32 bit
architectures.
Signed-off-by: Brice Goglin <brice@myri.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Since rb_insert_color() is part of the _public_ API, while the others are
purely internal, switch to be consistent with that.
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
People don't like released kernels yelling at them, no matter how real the
error might be. So only report it if CONFIG_KOBJECT_DEBUG is enabled.
Sent on request of Andrew Morton.
(akpm: should bring this back post-2.6.17)
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
For sparc32 we need R_SPARC_UA32 relocation support, for
sparc64 we need the handle R_SPARC_DISP32 relocations.
Based upon reports and initial patch by Martin Habets.
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch contains the following possible cleanups:
- #if 0 the following unused global function:
- subsys_remove_file()
- remove the following unused EXPORT_SYMBOL's:
- kset_find_obj
- subsystem_init
- remove the following unused EXPORT_SYMBOL_GPL:
- kobject_add_dir
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This fixes a build error for various odd combinations of CONFIG_HOTPLUG
and CONFIG_NET.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: Nigel Cunningham <ncunningham@cyclades.com>
Cc: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
We only used a single bit for colour information, so having a whole
machine word of space allocated for it was a bit wasteful. Instead,
store it in the lowest bit of the 'parent' pointer, since that was
always going to be aligned anyway.
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Observe rb_erase(), when the victim node 'old' has two children so
neither of the simple cases at the beginning are taken.
Observe that it effectively does an 'rb_next()' operation to find the
next (by value) node in the tree. That is; we go to the victim's
right-hand child and then follow left-hand pointers all the way
down the tree as far as we can until we find the next node 'node'. We
end up with 'node' being either the same immediate right-hand child of
'old', or one of its descendants on the far left-hand side.
For a start, we _know_ that 'node' has a parent. We can drop that check.
We also know that if 'node's parent is 'old', then 'node' is the
right-hand child of its parent. And that if 'node's parent is _not_
'old', then 'node' is the left-hand child of its parent.
So instead of checking for 'node->rb_parent == old' in one place and
also checking 'node's heritage separately when we're trying to change
its link from its parent, we can shuffle things around a bit and do
it like this...
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
DEBUG_MUTEX flag is on by default in current kernel configuration.
During performance testing, we saw mutex debug functions like
mutex_debug_check_no_locks_freed (called by kfree()) is expensive as it
goes through a global list of memory areas with mutex lock and do the
checking. For benchmarks such as Volanomark and Hackbench, we have seen
more than 40% drop in performance on some platforms. We suggest to set
DEBUG_MUTEX off by default. Or at least do that later when we feel that
the mutex changes in the current code have stabilized.
Signed-off-by: Tim Chen <tim.c.chen@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
It works like this:
Open the file
Read all the contents.
Call poll requesting POLLERR or POLLPRI (so select/exceptfds works)
When poll returns,
close the file and go to top of loop.
or lseek to start of file and go back to the 'read'.
Events are signaled by an object manager calling
sysfs_notify(kobj, dir, attr);
If the dir is non-NULL, it is used to find a subdirectory which
contains the attribute (presumably created by sysfs_create_group).
This has a cost of one int per attribute, one wait_queuehead per kobject,
one int per open file.
The name "sysfs_notify" may be confused with the inotify
functionality. Maybe it would be nice to support inotify for sysfs
attributes as well?
This patch also uses sysfs_notify to allow /sys/block/md*/md/sync_action
to be pollable
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Some string functions were safely overrideable in lib/string.c, but their
corresponding declarations in linux/string.h were not. Correct this, and
make strcspn overrideable.
Odds of someone wanting to do optimized assembly of these are small, but
for the sake of cleanliness, might as well bring them into line with the
rest of the file.
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Ingo Molnar