Using a #define ending in a semicolon is poor style and can lead to
unexpected code paths being executed.

Warn on uses of these #define types:

	#define foo[(...)] bar;
	#define foo[(...)]	\
		bar;

Based on a patch from Borislav Petkov.
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Networking files are generally more strictly conformant to linux-kernel
style so make checkpatch more verbose by default for patches to files or
when checking files in these directories.
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make the test system wide, modify the message too.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We attempt to search for compatible strings which use a variable token in
the documented name such as <chip> or <soc>.  While this was attempted to
be handled, it's utterly broken.

The desired forms of matching are:

vendor,<chip>-*
vendor,name<part#>-*

For <chip>, lower case characters and numbers are permitted.  For <part#>,
only numeric values are allowed.

With this change, the number of missing compatible strings reported in
arch/arm/boot/dts is reduced from 1071 to 960.
Reported-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: NRob Herring <robh@kernel.org>
Tested-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Cc: Florian Vaussard <florian.vaussard@epfl.ch>
Cc: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix 4 checkpatch warnings
WARNING: sizeof *tv should be sizeof(*tv)
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Convert printk to current pr_foo() logging functions.

Also add pr_fmt based on KBUILD_MODNAME to avoid repeating prefix.  Prefix
is now "atomic64_test: "
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Cc: Luca Barbieri <luca@luca-barbieri.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

- Coalesce formats

- "WARNING:" prefix unchanged to keep bug format.

- printk(KERN_DEFAULT not converted.

- define pr_fmt without prefix to avoid any default prefix update
  (suggested by Joe Perches).
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix checkpatch warning:
"WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable"
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix some checkpatch warnings:
WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Cc: Pablo Neira <pablo@netfilter.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Small typo and @return: -> Returns ...
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Cc: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use cpu_to_le32 instead of __constant_cpu_to_le32.
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

index has been removed from __radix_tree_delete_node in 449dd698
("mm: keep page cache radix tree nodes in check")
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change CONFIG_DEBUG_PI_LIST to be user-selectable, and add a title and
description.  Remove the dependency on DEBUG_RT_MUTEXES since they were
changed to use rbtrees, and there are other users of plists now.
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I use btree from 3.14-rc2 in my own module.  When the btree module is
removed, a warning arises:

 kmem_cache_destroy btree_node: Slab cache still has objects
 CPU: 13 PID: 9150 Comm: rmmod Tainted: GF          O 3.14.0-rc2 #1
 Hardware name: Inspur NF5270M3/NF5270M3, BIOS CHEETAH_2.1.3 09/10/2013
 Call Trace:
   dump_stack+0x49/0x5d
   kmem_cache_destroy+0xcf/0xe0
   btree_module_exit+0x10/0x12 [btree]
   SyS_delete_module+0x198/0x1f0
   system_call_fastpath+0x16/0x1b

The cause is that it doesn't release the last btree node, when height = 1
and fill = 1.

[akpm@linux-foundation.org: remove unneeded test of NULL]
Signed-off-by: NMinfei Huang <huangminfei@ucloud.cn>
Cc: Joern Engel <joern@logfs.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fixing 2 coccinelle warnings:
lib/vsprintf.c:2350:2-9: WARNING: Assignment of bool to 0/1
lib/vsprintf.c:2389:3-10: WARNING: Assignment of bool to 0/1
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

replace IS_ERR/PTR_ERR
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This restores the old behavior that existed before 2013-02-22, when
changes were made by 64dbfb44 ("decompressors: drop dependency on
CONFIG_EXPERT") and 5dc49c75 ("decompressors: make the default
XZ_DEC_* config match the selected architecture").

Disabling the filters only makes sense on embedded systems.
Signed-off-by: NLasse Collin <lasse.collin@tukaani.org>
Acked-by: NKyle McMartin <kyle@infradead.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Phillip Lougher <phillip@lougher.demon.co.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Replace pr_debug() in lib/plist.c test function plist_test() with
printk(KERN_DEBUG ...).

Without DEBUG defined, pr_debug() is complied out, but the entire
plist_test() function is already inside CONFIG_DEBUG_PI_LIST, so printk
should just be used directly.
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Reviewed-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NLasse Collin <lasse.collin@tukaani.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

For strncpy() and friends the source string may or may not have an actual
NUL character at the end.  The documentation is confusing in this because
it specifically mentions that you are passing a "NUL-terminated" string.
Wikipedia says that "C-string" is an alternative name we can use instead.

http://en.wikipedia.org/wiki/Null-terminated_stringSigned-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

... instead of naked numbers.

Stuff in sysrq.c used to set it to 8 which is supposed to mean above
default level so set it to DEBUG instead as we're terminating/killing all
tasks and we want to be verbose there.

Also, correct the check in x86_64_start_kernel which should be >= as
we're clearly issuing the string there for all debug levels, not only
the magical 10.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: Joe Perches <joe@perches.com>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If the log ring buffer becomes full, we silently overwrite old messages
with new data.  console_unlock will detect this case and fast-forward the
console_* pointers to skip over the corrupted data, but nothing will be
reported to the user.

This patch hijacks the first valid log message after detecting that we
dropped messages and prefixes it with a note detailing how many messages
were dropped.  For long (~1000 char) messages, this will result in some
truncation of the real message, but given that we're dropping things
anyway, that doesn't seem to be the end of the world.
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The pr_debug() and related debug print macros all differ from the normal
pr_XXX() macros, in that the normal ones print unconditionally, while
the debug macros are compiled out unless DEBUG is defined or
CONFIG_DYNAMIC_DEBUG is set.  This isn't obvious, and the only way to
find this out is either to review the actual printk.h code or to read
CodingStyle, and the message there doesn't highlight the fact.

Change Documentation/CodingStyle to clearly indicate that pr_debug() and
related debug printing macros behave differently than all other pr_XXX()
macros, and attempt to clarify when and where the different debug
printing methods might be used.

Add short comment to printk.h above the pr_XXX() macros indicating that
while these macros print unconditionally, pr_debug() does not.
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Cc: Joe Perches <joe@perches.com>
Cc: Fabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Jiri Bohac pointed out that there are rare but potential deadlock
possibilities when calling printk while holding the timekeeping
seqlock.

This is due to printk() triggering console sem wakeup, which can
cause scheduling code to trigger hrtimers which may try to read
the time.

Specifically, as Jiri pointed out, that path is:
  printk
    vprintk_emit
      console_unlock
        up(&console_sem)
          __up
	    wake_up_process
	      try_to_wake_up
	        ttwu_do_activate
		  ttwu_activate
		    activate_task
		      enqueue_task
		        enqueue_task_fair
			  hrtick_update
			    hrtick_start_fair
			      hrtick_start_fair
			        get_time
				  ktime_get
				    --> endless loop on
				    read_seqcount_retry(&timekeeper_seq, ...)

This patch tries to avoid this issue by using printk_deferred (previously
named printk_sched) which should defer printing via a irq_work_queue.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Reported-by: NJiri Bohac <jbohac@suse.cz>
Reviewed-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Two of the three prink_deferred uses are really printk_once style
uses, so add a printk_deferred_once macro to simplify those call
sites.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Reviewed-by: NSteven Rostedt <rostedt@goodmis.org>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

After learning we'll need some sort of deferred printk functionality in
the timekeeping core, Peter suggested we rename the printk_sched function
so it can be reused by needed subsystems.

This only changes the function name. No logic changes.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Reviewed-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

An earlier change in -mm (printk: remove separate printk_sched
buffers...), removed the printk_sched irqsave/restore lines since it was
safe for current users.  Since we may be expanding usage of
printk_sched(), disable preepmtion for this function to make it more
generally safe to call.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

To prevent deadlocks with doing a printk inside the scheduler,
printk_sched() was created.  The issue is that printk has a console_sem
that it can grab and release.  The release does a wake up if there's a
task pending on the sem, and this wake up grabs the rq locks that is
held in the scheduler.  This leads to a possible deadlock if the wake up
uses the same rq as the one with the rq lock held already.

What printk_sched() does is to save the printk write in a per cpu buffer
and sets the PRINTK_PENDING_SCHED flag.  On a timer tick, if this flag is
set, the printk() is done against the buffer.

There's a couple of issues with this approach.

1) If two printk_sched()s are called before the tick, the second one
   will overwrite the first one.

2) The temporary buffer is 512 bytes and is per cpu.  This is a quite a
   bit of space wasted for something that is seldom used.

In order to remove this, the printk_sched() can use the printk buffer
instead, and delay the console_trylock()/console_unlock() to the queued
work.

Because printk_sched() would then be taking the logbuf_lock, the
logbuf_lock must not be held while doing anything that may call into the
scheduler functions, which includes wake ups.  Unfortunately, printk()
also has a console_sem that it uses, and on release, the up(&console_sem)
may do a wake up of any pending waiters.  This must be avoided while
holding the logbuf_lock.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We need interrupts disabled when calling console_trylock_for_printk()
only so that cpu id we pass to can_use_console() remains valid (for
other things console_sem provides all the exclusion we need and
deadlocks on console_sem due to interrupts are impossible because we use
down_trylock()).  However if we are rescheduled, we are guaranteed to
run on an online cpu so we can easily just get the cpu id in
can_use_console().

We can lose a bit of performance when we enable interrupts in
vprintk_emit() and then disable them again in console_unlock() but OTOH
it can somewhat reduce interrupt latency caused by console_unlock()
especially since later in the patch series we will want to spin on
console_sem in console_trylock_for_printk().
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Printk calls mutex_acquire() / mutex_release() by hand to instrument
lockdep about console_sem.  However in some corner cases the
instrumentation is missing.  Fix the problem by creating helper functions
for locking / unlocking console_sem which take care of lockdep
instrumentation as well.
Signed-off-by: NJan Kara <jack@suse.cz>
Reported-by: NFabio Estevam <festevam@gmail.com>
Reported-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: NFabio Estevam <fabio.estevam@freescale.com>
Tested-By: NValdis Kletnieks <valdis.kletnieks@vt.edu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There's no reason to hold lockbuf_lock when entering
console_trylock_for_printk().

The first thing this function does is to call down_trylock(console_sem)
and if that fails it immediately unlocks lockbuf_lock.  So lockbuf_lock
isn't needed for that branch.  When down_trylock() succeeds, the rest of
console_trylock() is OK without lockbuf_lock (it is called without it
from other places), and the only remaining thing in
console_trylock_for_printk() is can_use_console() call.  For that call
console_sem is enough (it iterates all consoles and checks CON_ANYTIME
flag).

So we drop logbuf_lock before entering console_trylock_for_printk() which
simplifies the code.

[akpm@linux-foundation.org: fix have_callable_console() comment]
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Comment about interesting interlocking between lockbuf_lock and
console_sem is outdated.

It was added in 2002 by commit a880f45a48be during conversion of
console_lock to console_sem + lockbuf_lock.

At that time release_console_sem() (today's equivalent is
console_unlock()) was indeed using lockbuf_lock to avoid races between
trylock on console_sem in printk() and unlock of console_sem.  However
these days the interlocking is gone and the races are avoided by
rechecking logbuf state after releasing console_sem.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I wonder if anyone uses printk return value but it is there and should be
counted correctly.

This patch modifies log_store() to return the number of really stored
bytes from the 'text' part.  Also it handles the return value in
vprintk_emit().

Note that log_store() is used also in cont_flush() but we could ignore the
return value there.  The function works with characters that were already
counted earlier.  In addition, the store could newer fail here because the
length of the printed text is limited by the "cont" buffer and "dict" is
NULL.
Signed-off-by: NPetr Mladek <pmladek@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We might want to print at least part of too long messages and add some
warning for debugging purpose.

The question is how long the shrunken message should be.  If we use the
whole buffer, it might get rotated too soon.  Let's try to use only 1/4 of
the buffer for now.

Also shrink the whole dictionary.  We do not want to parse it or break it
in the middle of some pair of values.  It would not cause any real harm
but still.
Signed-off-by: NPetr Mladek <pmladek@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We will want to recompute the message size when shrinking too long
messages.  Let's put the code into separate function.

The side effect of setting "pad_len" is not nice but it is worth removing
the code duplication.  Note that I will probably have one more usage for
this function when handling messages safe way in NMI context.

This patch does not change the existing behavior.
Signed-off-by: NPetr Mladek <pmladek@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There was no check for too long messages.  The check for free space always
passed when first_seq and next_seq were equal.  Enough free space was not
guaranteed, though.

log_store() might be called to store messages up to 64kB + 64kB + 16B.
This is sum of maximal text_len, dict_len values, and the size of the
structure printk_log.

On the other hand, the minimal size for the main log buffer currently is
4kB and it is enforced only by Kconfig.

The good news is that the usage looks safe right now.  log_store() is
called only from vprintk_emit() and cont_flush().  Here the "text" part is
always passed via a static buffer and the length is limited to
LOG_LINE_MAX which is 1024.  The "dict" part is NULL in most cases.  The
only exceptions is when vprintk_emit() is called from printk_emit() and
dev_vprintk_emit().  But printk_emit() is currently used only in
devkmsg_writev() and here "dict" is NULL as well.  In dev_vprintk_emit(),
"dict" is limited by the static buffer "hdr" of the size 128 bytes.  It
meas that the current maximal printed text is 1024B + 128B + 16B and it
always fit the log buffer.

But it is only matter of time when someone calls printk_emit() with unsafe
parameters, especially the "dict" one.

This patch adds a check for the free space when the buffer is empty.  It
reuses the already existing log_has_space() function but it has to add an
extra parameter.  It defines whether the buffer is empty.  Note that the
same values of "first_idx" and "next_idx" might also mean that the buffer
is full.

If the buffer is empty, we must respect the current position of the
indexes.  We cannot reset them to the beginning of the buffer.  Otherwise,
the functions reading the buffer would get crazy.

The question is what to do when the message is too long.  This patch uses
the easiest solution and just ignores the problematic message.  Let's do
something better in a followup patch.
Signed-off-by: NPetr Mladek <pmladek@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The check for free space in the log buffer always passes when "first_seq"
and "next_seq" are equal.  In theory, it might cause writing outside of
the log buffer.

Fortunately, the current usage looks safe because the used "text" and
"dict" buffers are quite limited.  See the second patch for more details.

Anyway, it is better to be on the safe side and add a check.  An easy
solution is done in the 2nd patch and it is improved in the 4th patch.

5th patch fixes the computation of the printed message length.

1st and 3rd patches just do some code refactoring to make the other
patches easier.

This patch (of 5):

There will be needed some fixes in the check for free space.  They will be
easier if the code is moved outside of the quite long log_store()
function.

This patch does not change the existing behavior.
Signed-off-by: NPetr Mladek <pmladek@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Nobody seems uses it for a long time. Let's drop it.
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

sysctl_hung_task_panic has been changed to unsigned int.  use kstrtouint
instead of obsolete simple_strtoul
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>