Commit Graph

41 Commits

Author SHA1 Message Date
Paul Mundt 09682c1dd3 bug.h: Fix up CONFIG_BUG=n implicit function declarations.
Commit 2603efa31a ("bug.h: Fix up powerpc build regression") corrected
the powerpc build case and extended the __ASSEMBLY__ guards, but it also
got caught in pre-processor hell accidentally matching the else case of
CONFIG_BUG resulting in the BUG disabled case tripping up on
-Werror=implicit-function-declaration.

It's not possible to __ASSEMBLY__ guard the entire file as architecture
code needs to get at the BUGFLAG_WARNING definition in the GENERIC_BUG
case, but the rest of the CONFIG_BUG=y/n case needs to be guarded.

Rather than littering endless __ASSEMBLY__ checks in each of the if/else
cases we just move the BUGFLAG definitions up under their own
GENERIC_BUG test and then shove everything else under one big
__ASSEMBLY__ guard.

Build tested on all of x86 CONFIG_BUG=y, CONFIG_BUG=n, powerpc (due to
it's dependence on BUGFLAG definitions in assembly code), and sh (due to
not bringing in linux/kernel.h to satisfy the taint flag definitions used
by the generic bug code).

Hopefully that's the end of the corner cases and I can abstain from ever
having to touch this infernal header ever again.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Tested-by: Fengguang Wu <wfg@linux.intel.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-06-25 10:32:49 -07:00
Paul Mundt 2603efa31a bug.h: Fix up powerpc build regression.
The asm-generic/bug.h __ASSEMBLY__ guarding is completely bogus, which
tripped up the powerpc build when the kernel.h include was added:

	In file included from include/asm-generic/bug.h:5:0,
			 from arch/powerpc/include/asm/bug.h:127,
			 from arch/powerpc/kernel/head_64.S:31:
	include/linux/kernel.h:44:0: warning: "ALIGN" redefined [enabled by default]
	include/linux/linkage.h:57:0: note: this is the location of the previous definition
	include/linux/sysinfo.h: Assembler messages:
	include/linux/sysinfo.h:7: Error: Unrecognized opcode: `struct'
	include/linux/sysinfo.h:8: Error: Unrecognized opcode: `__kernel_long_t'

Moving the __ASSEMBLY__ guard up and stashing the kernel.h include under
it fixes this up, as well as covering the case the original fix was
attempting to handle.

Tested-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-06-18 11:10:59 -07:00
Paul Mundt 3777808873 bug.h: need linux/kernel.h for TAINT_WARN.
asm-generic/bug.h uses taint flags that are only defined in
linux/kernel.h, resulting in build failures on platforms that
don't include linux/kernel.h some other way:

        arch/sh/include/asm/thread_info.h:172:2: error: 'TAINT_WARN' undeclared (first use in this function)

Caused by commit edd63a2763 ("set_restore_sigmask() is never called
without SIGPENDING (and never should be)").

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2012-06-11 14:29:58 +09:00
Jan Beulich 7ccaba5314 consolidate WARN_...ONCE() static variables
Due to the alignment of following variables, these typically consume
more than just the single byte that 'bool' requires, and as there are a
few hundred instances, the cache pollution (not so much the waste of
memory) sums up.  Put these variables into their own section, outside of
any half way frequently used memory range.

Do the same also to the __warned variable of rcu_lockdep_assert().
(Don't, however, include the ones used by printk_once() and alike, as
they can potentially be hot.)

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-23 16:58:31 -07:00
Joe Perches b9075fa968 treewide: use __printf not __attribute__((format(printf,...)))
Standardize the style for compiler based printf format verification.
Standardized the location of __printf too.

Done via script and a little typing.

$ grep -rPl --include=*.[ch] -w "__attribute__" * | \
  grep -vP "^(tools|scripts|include/linux/compiler-gcc.h)" | \
  xargs perl -n -i -e 'local $/; while (<>) { s/\b__attribute__\s*\(\s*\(\s*format\s*\(\s*printf\s*,\s*(.+)\s*,\s*(.+)\s*\)\s*\)\s*\)/__printf($1, $2)/g ; print; }'

[akpm@linux-foundation.org: revert arch bits]
Signed-off-by: Joe Perches <joe@perches.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:54 -07:00
David S. Miller 86e4ca66e8 bug.h: Move ratelimit warn interfaces to ratelimit.h
As reported by Ingo Molnar, we still have configuration combinations
where use of the WARN_RATELIMIT interfaces break the build because
dependencies don't get met.

Instead of going down the long road of trying to make it so that
ratelimit.h can get included by kernel.h or asm-generic/bug.h,
just move the interface into ratelimit.h and make users have
to include that.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
2011-05-26 15:00:31 -04:00
David S. Miller 6b36783546 bug.h: Fix build with CONFIG_PRINTK disabled.
Based upon an email by Joe Perches.

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
2011-05-24 16:15:56 -04:00
Joe Perches b3eec79b07 bug.h: Add WARN_RATELIMIT
Add a generic mechanism to ratelimit WARN(foo, fmt, ...) messages
using a hidden per call site static struct ratelimit_state.

Also add an __WARN_RATELIMIT variant to be able to use a specific
struct ratelimit_state.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-05-23 17:37:43 -04:00
Steven Rostedt ccd0d44fad WARN_ON_SMP(): Add comment to explain ({0;})
The define to use ({0;}) for the !CONFIG_SMP case of WARN_ON_SMP()
can be confusing. As the WARN_ON_SMP() needs to be a nop when
CONFIG_SMP is not set, including all its parameters must not be
evaluated, and that it must work as both a stand alone statement
and inside an if condition, we define it to a funky ({0;}).

A simple "0" will not work as it causes gcc to give the warning that
the statement has no effect.

As this strange definition has raised a few eyebrows from some
major kernel developers, it is wise to document why we create such
a work of art.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-03-28 10:10:42 -04:00
Steven Rostedt 2092e6be82 WARN_ON_SMP(): Allow use in if() statements on UP
Both WARN_ON() and WARN_ON_SMP() should be able to be used in
an if statement.

	if (WARN_ON_SMP(foo)) { ... }

Because WARN_ON_SMP() is defined as a do { } while (0) on UP,
it can not be used this way.

Convert it to the same form that WARN_ON() is, even when
CONFIG_SMP is off.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <20110317192208.444147791@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-03-25 11:32:09 +01:00
Ben Hutchings b2be05273a panic: Allow warnings to set different taint flags
WARN() is used in some places to report firmware or hardware bugs that
are then worked-around.  These bugs do not affect the stability of the
kernel and should not set the flag for TAINT_WARN.  To allow for this,
add WARN_TAINT() and WARN_TAINT_ONCE() macros that take a taint number
as argument.

Architectures that implement warnings using trap instructions instead
of calls to warn_slowpath_*() now implement __WARN_TAINT(taint)
instead of __WARN().

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Acked-by: Helge Deller <deller@gmx.de>
Tested-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2010-05-19 08:36:48 +01:00
Cesar Eduardo Barros 42f247c83a WARN_ONCE(): use bool for boolean flag
Commit 7086745309 ("printk_once(): use bool
for boolean flag") changed printk_once() to use bool instead of int for
its guard variable.  Do the same change to WARN_ONCE() and WARN_ON_ONCE(),
for the same reasons.

This resulted in a reduction of 1462 bytes on a x86-64 defconfig:

   text    data     bss     dec     hex filename
8101271 1207116  992764 10301151         9d2edf vmlinux.before
8100553 1207148  991988 10299689         9d2929 vmlinux.after

Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: Daniel Walker <dwalker@fifo99.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 08:53:25 -08:00
Andi Kleen 57adc4d2db Eliminate thousands of warnings with gcc 3.2 build
When building with gcc 3.2 I get thousands of warnings such as

include/linux/gfp.h: In function `allocflags_to_migratetype':
include/linux/gfp.h:105: warning: null format string

due to passing a NULL format string to warn_slowpath() in

#define __WARN()		warn_slowpath(__FILE__, __LINE__, NULL)

Split this case out into a separate call.  This also shrinks the kernel
slightly:

          text    data     bss     dec     hex filename
       4802274  707668  712704 6222646  5ef336 vmlinux
          text    data     bss     dec     hex filename
       4799027  703572  712704 6215303  5ed687 vmlinux

due to removeing one argument from the commonly-called __WARN().

[akpm@linux-foundation.org: reduce scope of `empty']
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-05-06 16:36:09 -07:00
David Howells da60682c11 The default CONFIG_BUG=n version of BUG() should have an empty do...while
The default CONFIG_BUG=n version of BUG() should incorporate an empty a
do...while statement to avoid compilation weirdness.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-15 13:55:13 -07:00
David Brownell af9379c712 documentation: when to BUG(), and when to not BUG()
Provide some basic advice about when to use BUG()/BUG_ON(): never, unless
there's really no better option.

This matches my understanding of the standard policy ...  which seems not
to be written down so far, outside of LKML messages that I haven't
bookmarked.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-06 15:59:13 -08:00
Linus Torvalds 5f34fe1cfc Merge branch 'core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (63 commits)
  stacktrace: provide save_stack_trace_tsk() weak alias
  rcu: provide RCU options on non-preempt architectures too
  printk: fix discarding message when recursion_bug
  futex: clean up futex_(un)lock_pi fault handling
  "Tree RCU": scalable classic RCU implementation
  futex: rename field in futex_q to clarify single waiter semantics
  x86/swiotlb: add default swiotlb_arch_range_needs_mapping
  x86/swiotlb: add default phys<->bus conversion
  x86: unify pci iommu setup and allow swiotlb to compile for 32 bit
  x86: add swiotlb allocation functions
  swiotlb: consolidate swiotlb info message printing
  swiotlb: support bouncing of HighMem pages
  swiotlb: factor out copy to/from device
  swiotlb: add arch hook to force mapping
  swiotlb: allow architectures to override phys<->bus<->phys conversions
  swiotlb: add comment where we handle the overflow of a dma mask on 32 bit
  rcu: fix rcutorture behavior during reboot
  resources: skip sanity check of busy resources
  swiotlb: move some definitions to header
  swiotlb: allow architectures to override swiotlb pool allocation
  ...

Fix up trivial conflicts in
  arch/x86/kernel/Makefile
  arch/x86/mm/init_32.c
  include/linux/hardirq.h
as per Ingo's suggestions.
2008-12-30 16:10:19 -08:00
Jan Beulich b93a531e31 allow bug table entries to use relative pointers (and use it on x86-64)
Impact: reduce bug table size

This allows reducing the bug table size by half. Perhaps there are
other 64-bit architectures that could also make use of this.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-16 18:40:32 +01:00
Ingo Molnar ec5679e513 debug warnings: eliminate warn_on_slowpath()
Impact: cleanup, eliminate code

now that warn_on_slowpath() uses warn_slowpath(...,NULL), we can
eliminate warn_on_slowpath() altogether and use warn_slowpath().

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-28 17:56:14 +01:00
Arjan van de Ven f6f286f33e fix WARN() for PPC
powerpc doesn't use the generic WARN_ON infrastructure.  The newly
introduced WARN() as a result didn't print the message, this patch adds
the printk for this specific case.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-20 15:29:57 -07:00
Harvey Harrison d5c003b4d1 include: replace __FUNCTION__ with __func__
__FUNCTION__ is gcc-specific, use __func__

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-16 11:21:30 -07:00
Arjan van de Ven 45e9c0de2e warn: Turn the netdev timeout WARN_ON() into a WARN()
this patch turns the netdev timeout WARN_ON_ONCE() into a WARN_ONCE(),
so that the device and driver names are inside the warning message.
This helps automated tools like kerneloops.org to collect the data
and do statistics, as well as making it more likely that humans
cut-n-paste the important message as part of a bugreport.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-09-16 19:39:33 -07:00
Dave Young 717115e1a5 printk ratelimiting rewrite
All ratelimit user use same jiffies and burst params, so some messages
(callbacks) will be lost.

For example:
a call printk_ratelimit(5 * HZ, 1)
b call printk_ratelimit(5 * HZ, 1) before the 5*HZ timeout of a, then b will
will be supressed.

- rewrite __ratelimit, and use a ratelimit_state as parameter.  Thanks for
  hints from andrew.

- Add WARN_ON_RATELIMIT, update rcupreempt.h

- remove __printk_ratelimit

- use __ratelimit in net_ratelimit

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 10:53:29 -07:00
Arjan van de Ven a8f18b909c Add a WARN() macro; this is WARN_ON() + printk arguments
Add a WARN() macro that acts like WARN_ON(), with the added feature that it
takes a printk like argument that is printed as part of the warning message.

[akpm@linux-foundation.org: fix printk arguments]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Greg KH <greg@kroah.com>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 10:53:29 -07:00
Arjan van de Ven 79b4cc5ee7 debug: move WARN_ON() out of line
A quick grep shows that there are currently 1145 instances of WARN_ON
in the kernel. Currently, WARN_ON is pretty much entirely inlined,
which makes it hard to enhance it without growing the size of the kernel
(and getting Andrew unhappy).

This patch build on top of Olof's patch that introduces __WARN,
and places the slowpath out of line. It also uses Ingo's suggestion
to not use __FUNCTION__ but to use kallsyms to do the lookup;
this saves a ton of extra space since gcc doesn't need to store the function
string twice now:

3936367  833603  624736 5394706  525112 vmlinux.before
3917508  833603  624736 5375847  520767 vmlinux-slowpath

15Kb savings...

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Olof Johansson <olof@lixom.net>
Acked-by: Matt Meckall <mpm@selenic.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:32:50 +01:00
Olof Johansson 3a6a62f96f debug: introduce __WARN()
Introduce __WARN() in the generic case, so the generic WARN_ON()
can use arch-specific code for when the condition is true.

Signed-off-by: Olof Johansson <olof@lixom.net>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:32:50 +01:00
Linus Torvalds 8d4fbcfbe0 Fix WARN_ON() on bitfield ops
Alexey Dobriyan noticed that the new WARN_ON() semantics that were
introduced by commit 684f978347 (to also
return the value to be warned on) didn't compile when given a bitfield,
because the typeof doesn't work for bitfields.

So instead of the typeof trick, use an "int" variable together with a
"!!(x)" expression, as suggested by Al Viro.

To make matters more interesting, Paul Mackerras points out that that is
sub-optimal on Power, but the old asm-coded comparison seems to be buggy
anyway on 32-bit Power if the conditional was 64-bit, so I think there
are more problems there.

Regardless, the new WARN_ON() semantics may have been a bad idea.  But
this at least avoids the more serious complications.

Cc: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2007-07-31 21:12:07 -07:00
Alexey Dobriyan 2a41de48b8 Fix sparse false positives re BUG_ON(ptr)
sparse now warns if one compares pointers with integers. However, there are
false positives, like:

	fs/filesystems.c:72:2: warning: Using plain integer as NULL pointer

Every time BUG_ON(ptr) is used, ptr is checked against integer zero.  Avoid
that and save ~70 false positives from allyesconfig run.

mentioned by Al.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Josh Triplett <josh@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:03 -07:00
Linus Torvalds 8f53b6fcc4 Don't call a warnign a bug. It's a warning.
Change the default printout message for WARN_ON() to say what it is, not
something else.  I'm tired of having people get all aflutter about a warning.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-24 10:13:43 -07:00
Ingo Molnar 52e88f5d4a [PATCH] change WARN_ON back to "BUG: at ..."
WARN_ON() ever triggering is a kernel bug.  Do not try to paper over this
fact by suggesting to the user that this is 'only' a warning, as the
following recent commit does:

  commit 30e25b71e7
  Author: Jeremy Fitzhardinge <jeremy@goop.org>
  Date:   Fri Dec 8 02:36:24 2006 -0800

    [PATCH] Fix generic WARN_ON message

    A warning is a warning, not a BUG.

( it might make sense to rename BUG() to CRASH() and BUG_ON() to
  CRASH_ON(), but that does not change the fact that WARN_ON()
  signals a kernel bug. )

i and others objected to this change during lkml review:

  http://marc.theaimsgroup.com/?l=linux-kernel&m=116115160710533&w=2

still the change slipped upstream - grumble :)

Also, use the standard "BUG: " format to make it easier to grep logs and
to make it easier to google for kernel bugs.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-30 10:55:54 -08:00
Jeremy Fitzhardinge 30e25b71e7 [PATCH] Fix generic WARN_ON message
A warning is a warning, not a BUG.

Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 08:28:39 -08:00
Jeremy Fitzhardinge 7664c5a1da [PATCH] Generic BUG implementation
This patch adds common handling for kernel BUGs, for use by architectures as
they wish.  The code is derived from arch/powerpc.

The advantages of having common BUG handling are:
 - consistent BUG reporting across architectures
 - shared implementation of out-of-line file/line data
 - implement CONFIG_DEBUG_BUGVERBOSE consistently

This means that in inline impact of BUG is just the illegal instruction
itself, which is an improvement for i386 and x86-64.

A BUG is represented in the instruction stream as an illegal instruction,
which has file/line information associated with it.  This extra information is
stored in the __bug_table section in the ELF file.

When the kernel gets an illegal instruction, it first confirms it might
possibly be from a BUG (ie, in kernel mode, the right illegal instruction).
It then calls report_bug().  This searches __bug_table for a matching
instruction pointer, and if found, prints the corresponding file/line
information.  If report_bug() determines that it wasn't a BUG which caused the
trap, it returns BUG_TRAP_TYPE_NONE.

Some architectures (powerpc) implement WARN using the same mechanism; if the
illegal instruction was the result of a WARN, then report_bug(Q) returns
CONFIG_DEBUG_BUGVERBOSE; otherwise it returns BUG_TRAP_TYPE_BUG.

lib/bug.c keeps a list of loaded modules which can be searched for __bug_table
entries.  The architecture must call
module_bug_finalize()/module_bug_cleanup() from its corresponding
module_finalize/cleanup functions.

Unsetting CONFIG_DEBUG_BUGVERBOSE will reduce the kernel size by some amount.
At the very least, filename and line information will not be recorded for each
but, but architectures may decide to store no extra information per BUG at
all.

Unfortunately, gcc doesn't have a general way to mark an asm() as noreturn, so
architectures will generally have to include an infinite loop (or similar) in
the BUG code, so that gcc knows execution won't continue beyond that point.
gcc does have a __builtin_trap() operator which may be useful to achieve the
same effect, unfortunately it cannot be used to actually implement the BUG
itself, because there's no way to get the instruction's address for use in
generating the __bug_table entry.

[randy.dunlap@oracle.com: Handle BUG=n, GENERIC_BUG=n to prevent build errors]
[bunk@stusta.de: include/linux/bug.h must always #include <linux/module.h]
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andi Kleen <ak@muc.de>
Cc: Hugh Dickens <hugh@veritas.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 08:28:39 -08:00
Ralf Baechle 8c7c7c9bf3 [PATCH] Fix warnings for WARN_ON if CONFIG_BUG is disabled
In most cases the return value of WARN_ON() is ignored.  If the generic
definition for the !CONFIG_BUG case is used this will result in a warning:

  CC      kernel/sched.o
In file included from include/linux/bio.h:25,
                 from include/linux/blkdev.h:14,
                 from kernel/sched.c:39:
include/linux/ioprio.h: In function ‘task_ioprio’:
include/linux/ioprio.h:50: warning: statement with no effect
kernel/sched.c: In function ‘context_switch’:
kernel/sched.c:1834: warning: statement with no effect

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-20 10:26:38 -07:00
Andrew Morton d69a892268 [PATCH] Fix WARN_ON / WARN_ON_ONCE regression
Tim and Ananiev report that the recent WARN_ON_ONCE changes cause increased
cache misses with the tbench workload.  Apparently due to the access to the
newly-added static variable.

Rearrange the code so that we don't touch that variable unless the warning is
going to trigger.

Also rework the logic so that the static variable starts out at zero, so we
can move it into bss.

It would seem logical to mark the static variable as __read_mostly too.  But
it would be wrong, because that would put it back into the vmlinux image, and
the kernel will never read from this variable in normal operation anyway.
Unless the compiler or hardware go and do some prefetching on us?

For some reason this patch shrinks softirq.o text by 40 bytes.

Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "Ananiev, Leonid I" <leonid.i.ananiev@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-06 08:53:39 -07:00
Herbert Xu 684f978347 [PATCH] Let WARN_ON/WARN_ON_ONCE return the condition
Letting WARN_ON/WARN_ON_ONCE return the condition means that you could do

if (WARN_ON(blah)) {
	handle_impossible_case
}

Rather than

if (unlikely(blah)) {
	WARN_ON(1)
	handle_impossible_case
}

I checked all the newly added WARN_ON_ONCE users and none of them test the
return status so we can still change it.

[akpm@osdl.org: warning fix]
[akpm@osdl.org: build fix]
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-29 09:18:06 -07:00
Ingo Molnar 8eb94f80dd [PATCH] pi-futex: introduce WARN_ON_SMP
Introduce a new WARN_ON variant: WARN_ON_SMP(cond).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27 17:32:46 -07:00
Ingo Molnar 74bb6a09b2 [PATCH] introduce WARN_ON_ONCE(cond)
Add WARN_ON_ONCE(cond) to print once-per-bootup messages.

[rostedt@goodmis.org: improve code generation]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-25 10:01:11 -07:00
David Woodhouse 62c4f0a2d5 Don't include linux/config.h from anywhere else in include/
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2006-04-26 12:56:16 +01:00
Ingo Molnar 91368d73e4 [PATCH] make bug messages more consistent
Consolidate all kernel bug printouts to begin with the "BUG: " string.
Makes it easier to find them in large bootup logs.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-23 07:38:16 -08:00
Matt Mackall cd7619d6bf [PATCH] Exterminate PAGE_BUG
Remove PAGE_BUG - repalce it with BUG and BUG_ON.

Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-01 08:59:01 -07:00
Matt Mackall c8538a7aa5 [PATCH] remove all kernel BUGs
This patch eliminates all kernel BUGs, trims about 35k off the typical
kernel, and makes the system slightly faster.

Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-01 08:59:01 -07:00
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00