BUILD_BUG_ON used to use the optimizer to do code elimination or fail
at link time; it was changed to first the size of a negative array (a
nicer compile time error), then (in
8c87df457c) to a bitfield.
This forced us to change some non-constant cases to MAYBE_BUILD_BUG_ON();
as Jan points out in that commit, it didn't work as intended anyway.
bitfields: needs a literal constant at parse time, and can't be put under
"if (__builtin_constant_p(x))" for example.
negative array: can handle anything, but if the compiler can't tell it's
a constant, silently has no effect.
link time: breaks link if the compiler can't determine the value, but the
linker output is not usually as informative as a compiler error.
If we use the negative-array-size method *and* the link time trick,
we get the ability to use BUILD_BUG_ON() under __builtin_constant_p()
branches, and maximal ability for the compiler to detect errors at
build time.
We also document it thoroughly.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jan Beulich <JBeulich@novell.com>
Acked-by: Hollis Blanchard <hollisb@us.ibm.com>
During early boot, local IRQ is disabled until IRQ subsystem is
properly initialized. During this time, no one should enable
local IRQ and some operations which usually are not allowed with
IRQ disabled, e.g. operations which might sleep or require
communications with other processors, are allowed.
lockdep tracked this with early_boot_irqs_off/on() callbacks.
As other subsystems need this information too, move it to
init/main.c and make it generally available. While at it,
toggle the boolean to early_boot_irqs_disabled instead of
enabled so that it can be initialized with %false and %true
indicates the exceptional condition.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110120110635.GB6036@htj.dyndns.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Lumpy reclaim is disruptive. It reclaims a large number of pages and
ignores the age of the pages it reclaims. This can incur significant
stalls and potentially increase the number of major faults.
Compaction has reached the point where it is considered reasonably stable
(meaning it has passed a lot of testing) and is a potential candidate for
displacing lumpy reclaim. This patch introduces an alternative to lumpy
reclaim whe compaction is available called reclaim/compaction. The basic
operation is very simple - instead of selecting a contiguous range of
pages to reclaim, a number of order-0 pages are reclaimed and then
compaction is later by either kswapd (compact_zone_order()) or direct
compaction (__alloc_pages_direct_compact()).
[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: use conventional task_struct naming]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michal reports:
In the framebuffer subsystem the abs() macro is often used as a part of
the calculation of a Manhattan metric, which in turn is used as a measure
of similarity between video modes. The arguments of abs() are sometimes
unsigned numbers. This worked fine until commit a49c59c0 ("Make sure the
value in abs() does not get truncated if it is greater than 2^32:) , which
changed the definition of abs() to prevent truncation. As a result of
this change, in the following piece of code:
u32 a = 0, b = 1;
u32 c = abs(a - b);
'c' will end up with a value of 0xffffffff instead of the expected 0x1.
A problem caused by this change and visible by the end user is that
framebuffer drivers relying on functions from modedb.c will fail to find
high resolution video modes similar to that explicitly requested by the
user if an exact match cannot be found (see e.g.
Fix this by special-casing `long' types within abs().
This patch reduces x86_64 code size a bit - drivers/video/uvesafb.o shrunk
by 15 bytes, presumably because it is doing abs() on 4-byte quantities,
and expanding those to 8-byte longs adds code.
testcase:
#define oldabs(x) ({ \
long __x = (x); \
(__x < 0) ? -__x : __x; \
})
#define newabs(x) ({ \
long ret; \
if (sizeof(x) == sizeof(long)) { \
long __x = (x); \
ret = (__x < 0) ? -__x : __x; \
} else { \
int __x = (x); \
ret = (__x < 0) ? -__x : __x; \
} \
ret; \
})
typedef unsigned int u32;
main()
{
u32 a = 0;
u32 b = 1;
u32 oldc = oldabs(a - b);
u32 newc = newabs(a - b);
printf("%u %u\n", oldc, newc);
}
akpm:/home/akpm> gcc t.c
akpm:/home/akpm> ./a.out
4294967295 1
Reported-by: Michal Januszewski <michalj@gmail.com>
Cc: Rolf Eike Beer <eike-kernel@sf-tec.de
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Similar to the kgdb_hex2mem() code, hex2bin converts a string
to binary using the hex_to_bin() library call.
Changelog:
- Replace parameter names with src/dst (based on David Howell's comment)
- Add 'const' where needed (based on David Howell's comment)
- Replace int with size_t (based on David Howell's comment)
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
Move the logging bits from kernel.h into printk.h so that
there is a bit more logical separation of the generic from
the printk logging specific parts.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kernel syslog contains debugging information that is often useful
during exploitation of other vulnerabilities, such as kernel heap
addresses. Rather than futilely attempt to sanitize hundreds (or
thousands) of printk statements and simultaneously cripple useful
debugging functionality, it is far simpler to create an option that
prevents unprivileged users from reading the syslog.
This patch, loosely based on grsecurity's GRKERNSEC_DMESG, creates the
dmesg_restrict sysctl. When set to "0", the default, no restrictions are
enforced. When set to "1", only users with CAP_SYS_ADMIN can read the
kernel syslog via dmesg(8) or other mechanisms.
[akpm@linux-foundation.org: explain the config option in kernel.txt]
Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Eugene Teo <eugeneteo@kernel.org>
Acked-by: Kees Cook <kees.cook@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
printk_ratelimit() was a bad idea - we don't want subsytem A causing
ratelimiting of subsystem B's messages.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The whole point to using the strict functions is to check the return
value. If you don't, strict_strto*() will return you uninitialised
garbage. Offenders have been observed in the wild.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce two additional min/max macros to compare three operands. This
will save some cycles as well as some bytes on the stack and last but not
least more pleasing as macro nesting.
[akpm@linux-foundation.org: fix warnings]
Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: Joe Perches <joe@perches.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-2.6.37/core' of git://git.kernel.dk/linux-2.6-block: (39 commits)
cfq-iosched: Fix a gcc 4.5 warning and put some comments
block: Turn bvec_k{un,}map_irq() into static inline functions
block: fix accounting bug on cross partition merges
block: Make the integrity mapped property a bio flag
block: Fix double free in blk_integrity_unregister
block: Ensure physical block size is unsigned int
blkio-throttle: Fix possible multiplication overflow in iops calculations
blkio-throttle: limit max iops value to UINT_MAX
blkio-throttle: There is no need to convert jiffies to milli seconds
blkio-throttle: Fix link failure failure on i386
blkio: Recalculate the throttled bio dispatch time upon throttle limit change
blkio: Add root group to td->tg_list
blkio: deletion of a cgroup was causes oops
blkio: Do not export throttle files if CONFIG_BLK_DEV_THROTTLING=n
block: set the bounce_pfn to the actual DMA limit rather than to max memory
block: revert bad fix for memory hotplug causing bounces
Fix compile error in blk-exec.c for !CONFIG_DETECT_HUNG_TASK
block: set the bounce_pfn to the actual DMA limit rather than to max memory
block: Prevent hang_check firing during long I/O
cfq: improve fsync performance for small files
...
Fix up trivial conflicts due to __rcu sparse annotation in include/linux/genhd.h
Currently the roundup macro references it's arguments more than one time.
This patch changes it so it will only use its arguments once.
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
The roundup() helper function will round a given value up to a multiple of
another given value. aka roundup(11, 7) would give 14 = 7 * 2. This new
function does the opposite. It will round a given number down to the
nearest multiple of the second number: rounddown(11, 7) would give 7.
I need this in some future SELinux code and can carry the macro myself, but
figured I would put it in the core kernel so others might find and use it
if need be.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
We have several users of min_not_zero, each of them using their own
definition. Move the define to kernel.h.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@carl.home.kernel.dk>
Add a dummy printk function for the maintenance of unused printks through gcc
format checking, and also so that side-effect checking is maintained too.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To keep panic_timeout accuracy when running under a hypervisor, the
current implementation only spins on long time (1 second) calls to mdelay.
That brings a good effect, but the problem is the keyboard LEDs don't
blink at all on that situation.
This patch changes to call to panic_blink_enter() between every mdelay and
keeps blinking in spite of long spin timer mode.
The time to call to mdelay is now 100ms. Even this change will keep
panic_timeout accuracy enough when running under a hypervisor.
Signed-off-by: TAMUKI Shoichi <tamuki@linet.gr.jp>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Cc: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (162 commits)
tracing/kprobes: unregister_trace_probe needs to be called under mutex
perf: expose event__process function
perf events: Fix mmap offset determination
perf, powerpc: fsl_emb: Restore setting perf_sample_data.period
perf, powerpc: Convert the FSL driver to use local64_t
perf tools: Don't keep unreferenced maps when unmaps are detected
perf session: Invalidate last_match when removing threads from rb_tree
perf session: Free the ref_reloc_sym memory at the right place
x86,mmiotrace: Add support for tracing STOS instruction
perf, sched migration: Librarize task states and event headers helpers
perf, sched migration: Librarize the GUI class
perf, sched migration: Make the GUI class client agnostic
perf, sched migration: Make it vertically scrollable
perf, sched migration: Parameterize cpu height and spacing
perf, sched migration: Fix key bindings
perf, sched migration: Ignore unhandled task states
perf, sched migration: Handle ignored migrate out events
perf: New migration tool overview
tracing: Drop cpparg() macro
perf: Use tracepoint_synchronize_unregister() to flush any pending tracepoint call
...
Fix up trivial conflicts in Makefile and drivers/cpufreq/cpufreq.c
