linux-toradex.git/lib/ratelimit.c, branch v4.9.16

ratelimit: extend to print suppressed messages on release

2016-08-02T23:35:06+00:00

Extend the ratelimiting facility to print the amount of suppressed lines
when it is being released.

This use case is aimed at short-termed, burst-like users for which we
want to output the suppressed lines stats only once, after it has been
disposed of.  For an example, see /dev/kmsg usage in a follow-on patch.

Also, change the printk() line we issue on release to not use
"callbacks" as it is misleading: we're not suppressing callbacks but
printk() calls.

This has been separated from a previous patch by Linus.

Link: http://lkml.kernel.org/r/20160716061745.15795-2-bp@alien8.de
Signed-off-by: Borislav Petkov 
Cc: Dave Young 
Cc: Franck Bui 
Cc: Greg Kroah-Hartman 
Cc: Ingo Molnar 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Uwe Kleine-König 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ratelimit: fix bug in time interval by resetting right begin time

2016-01-22T01:20:51+00:00

rs->begin in ratelimit is set in two cases.
 1) when rs->begin was not initialized
 2) when rs->interval was passed

For case #2, current ratelimit sets the begin to 0.  This incurrs
improper suppression.  The begin value will be set in the next ratelimit
call by 1).  Then the time interval check will be always false, and
rs->printed will not be initialized.  Although enough time passed,
ratelimit may return 0 if rs->printed is not less than rs->burst.  To
reset interval properly, begin should be jiffies rather than 0.

For an example code below:

    static DEFINE_RATELIMIT_STATE(mylimit, 1, 1);
    for (i = 1; i <= 10; i++) {
        if (__ratelimit(&mylimit))
            printk("ratelimit test count %d\n", i);
        msleep(3000);
    }

test result in the current code shows suppression even there is 3 seconds sleep.

  [  78.391148] ratelimit test count 1
  [  81.295988] ratelimit test count 2
  [  87.315981] ratelimit test count 4
  [  93.336267] ratelimit test count 6
  [  99.356031] ratelimit test count 8
  [ 105.376367] ratelimit test count 10

Signed-off-by: Jaewon Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lib: reduce the use of module.h wherever possible

2012-03-07T20:04:04+00:00

For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include.  Fix up any implicit
include dependencies that were being masked by module.h along
the way.

Signed-off-by: Paul Gortmaker

locking, printk: Annotate logbuf_lock as raw

2011-09-13T09:11:54+00:00

The logbuf_lock lock can be taken in atomic context and therefore
cannot be preempted on -rt - annotate it.

In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.

Signed-off-by: Thomas Gleixner 
[ merged and fixed it ]
Signed-off-by: Ingo Molnar

ratelimit: fix the return value when __ratelimit() fails to acquire the lock

2010-04-07T15:38:04+00:00

The log of commit edaac8e3167501cda336231d00611bf59c164346 ("ratelimit:
Fix/allow use in atomic contexts"), indicates that we want to suppress the
callback when the trylock fails.

Signed-off-by: Yong Zhang 
Cc: Ingo Molnar 
Cc: Christian Borntraeger 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ratelimit: annotate ___ratelimit()

2010-04-07T15:38:04+00:00

To prevent from wrongly using the return value.

[akpm@linux-foundation.org: fix spello]
Signed-off-by: Yong Zhang 
Cc: Ingo Molnar 
Cc: Dave Young 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ratelimit: Make suppressed output messages more useful

2009-10-23T15:26:37+00:00

Today I got:

  [39648.224782] Registered led device: iwl-phy0::TX
  [40676.545099] __ratelimit: 246 callbacks suppressed
  [40676.545103] abcdef[23675]: segfault at 0 ...

as you can see the ratelimit message contains a function prefix.
Since this is always __ratelimit, this wont help much.

This patch changes __ratelimit and printk_ratelimit to print the
function name that calls ratelimit.

This will pinpoint the responsible function, as long as not several
different places call ratelimit with the same ratelimit state at
the same time. In that case we catch only one random function that
calls ratelimit after the wait period.

Signed-off-by: Christian Borntraeger 
Cc: Dave Young 
Cc: Linus Torvalds 
CC: Andrew Morton 
LKML-Reference: <200910231458.11832.borntraeger@de.ibm.com>
Signed-off-by: Ingo Molnar

printk: Remove ratelimit.h from kernel.h

2009-09-22T14:18:09+00:00

Decouple kernel.h from ratelimit.h: the global declaration of
printk's ratelimit_state is not needed, and it leads to messy
circular dependencies due to ratelimit.h's (new) adding of a
spinlock_types.h include.

Cc: Peter Zijlstra 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: David S. Miller 
LKML-Reference: 
Signed-off-by: Ingo Molnar

ratelimit: Fix/allow use in atomic contexts

2009-09-22T12:05:48+00:00

I'd like to use printk_ratelimit() in NMI context, but it's not
robust right now due to spinlock usage in lib/ratelimit.c. If an
NMI is unlucky enough to hit just that spot we might lock up trying
to take the spinlock again.

Fix that by using a trylock variant. If we contend on that lock we
can genuinely skip the message because the state is just being
accessed by another CPU (or by this CPU).

( We could use atomics for the suppressed messages field, but
  i doubt it matters in practice and it makes the code heavier. )

Cc: Peter Zijlstra 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: David S. Miller 
LKML-Reference: 
Signed-off-by: Ingo Molnar

ratelimit: Use per ratelimit context locking

2009-09-22T13:31:34+00:00

I'd like to use printk_ratelimit() in atomic context, but that's
not possible right now due to the spinlock usage this commit
introduced more than a year ago:

  717115e: printk ratelimiting rewrite

As a first step push the lock into the ratelimit state structure.
This allows us to deal with locking failures to be considered as an
event related to that state being too busy.

Also clean up the code a bit (without changing functionality):

 - tidy up the definitions

 - clean up the code flow

This also shrinks the code a tiny bit:

   text	   data	    bss	    dec	    hex	filename
    264	      0	      4	    268	    10c	ratelimit.o.before
    255	      0	      0	    255	     ff	ratelimit.o.after

( Whole-kernel data size got a bit larger, because we have
  two ratelimit-state data structures right now. )

Cc: Peter Zijlstra 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: David S. Miller 
LKML-Reference: 
Signed-off-by: Ingo Molnar