linux-toradex.git/kernel/printk.c, branch v2.6.27.50

printk: robustify printk, fix #2

2010-04-01T22:52:17+00:00

commit fa33507a22623b3bd543b15a21c362cf364b6cff upstream.

Dmitry Adamushko reported:

> [*] btw., with DEBUG being enabled, pr_debug() generates [1] when
> debug_smp_processor_id() is used (CONFIG_DEBUG_PREEMPT).
>
> the problem seems to be caused by the following commit:
> commit b845b517b5e3706a3729f6ea83b88ab85f0725b0
> Author: Peter Zijlstra 
> Date:   Fri Aug 8 21:47:09 2008 +0200
>
>     printk: robustify printk
>
>
> wake_up_klogd() -> __get_cpu_var() -> smp_processor_id()
>
> and that's being called from release_console_sem() which is, in turn,
> said to be "may be called from any context" [2]
>
> and in this case, it seems to be called from some non-preemptible
> context (although, it can't be printk()...
> although, I haven't looked carefully yet).
>
> Provided [2], __get_cpu_var() is perhaps not the right solution there.
>
>
> [1]
>
> [ 7697.942005] BUG: using smp_processor_id() in preemptible [00000000] code: syslogd/3542
> [ 7697.942005] caller is wake_up_klogd+0x1b/0x50
> [ 7697.942005] Pid: 3542, comm: syslogd Not tainted 2.6.27-rc3-tip-git #2
> [ 7697.942005] Call Trace:
> [ 7697.942005]  [] debug_smp_processor_id+0xe8/0xf0
> [ 7697.942005]  [] wake_up_klogd+0x1b/0x50
> [ 7697.942005]  [] release_console_sem+0x1e7/0x200
> [ 7697.942005]  [] do_con_write+0xb7/0x1f30
> [ 7697.942005]  [] ? show_trace+0x10/0x20
> [ 7697.942005]  [] ? dump_stack+0x72/0x80
> [ 7697.942005]  [] ? __ratelimit+0xbd/0xe0
> [ 7697.942005]  [] ? debug_smp_processor_id+0xe8/0xf0
> [ 7697.942005]  [] ? wake_up_klogd+0x1b/0x50
> [ 7697.942005]  [] ? release_console_sem+0x1e7/0x200
> [ 7697.942005]  [] con_write+0x19/0x30
> [ 7697.942005]  [] write_chan+0x276/0x3c0
> [ 7697.942005]  [] ? default_wake_function+0x0/0x10
> [ 7697.942005]  [] ? _spin_lock_irqsave+0x22/0x50
> [ 7697.942005]  [] tty_write+0x194/0x260
> [ 7697.942005]  [] ? write_chan+0x0/0x3c0
> [ 7697.942005]  [] redirected_tty_write+0xa4/0xb0
> [ 7697.942005]  [] ? redirected_tty_write+0x0/0xb0
> [ 7697.942005]  [] do_loop_readv_writev+0x52/0x80
> [ 7697.942005]  [] do_readv_writev+0x1bd/0x1d0
> [ 7697.942005]  [] vfs_writev+0x39/0x60
> [ 7697.942005]  [] sys_writev+0x50/0x90
> [ 7697.942005]  [] system_call_fastpath+0x16/0x1b

Signed-off-by: Peter Zijlstra 
Reported-by: Dmitry Adamushko 
Signed-off-by: Ingo Molnar 
Cc: Paul Gortmaker 
Signed-off-by: Greg Kroah-Hartman

printk: robustify printk

2009-11-10T00:52:43+00:00

commit b845b517b5e3706a3729f6ea83b88ab85f0725b0 upstream.

Avoid deadlocks against rq->lock and xtime_lock by deferring the klogd
wakeup by polling from the timer tick.

Signed-off-by: Peter Zijlstra 
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

System call wrappers part 27

2009-01-18T18:35:39+00:00

commit 1e7bfb2134dfec37ce04fb3a4ca89299e892d10c upstream.

Signed-off-by: Heiko Carstens 
Signed-off-by: Greg Kroah-Hartman

Make sys_syslog a conditional system call

2009-01-18T18:35:33+00:00

commit f627a741d24f12955fa2d9f8831c3b12860635bd upstream.

Remove the -ENOSYS implementation for !CONFIG_PRINTK and use
the cond_syscall infrastructure instead.

Acked-by: Kyle McMartin 
Signed-off-by: Heiko Carstens 
Signed-off-by: Greg Kroah-Hartman

printk: fix comment for printk ratelimiting

2008-07-30T16:41:45+00:00

The comment assumed the burst to be one and the ratelimit used to be named
printk_ratelimit_jiffies.

Signed-off-by: Uwe Kleine-König 
Cc: Dave Young 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

printk ratelimiting rewrite

2008-07-25T17:53:29+00:00

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 
Cc: "David S. Miller" 
Cc: "Paul E. McKenney" 
Cc: Dave Young 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

swsusp: provide users with a hint about the no_console_suspend option

2008-07-24T17:47:22+00:00

Tell the user about the no_console_suspend option, so that we don't have to
tell each bug reporter personally.

[akpm@linux-foundation.org: clarify the text a little]
Signed-off-by: Pavel Machek 
Cc: "Rafael J. Wysocki" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'core/printk' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2008-07-14T22:27:43+00:00

* 'core/printk' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, generic: mark early_printk as asmlinkage
  printk: export console_drivers
  printk: remember the message level for multi-line output
  printk: refactor processing of line severity tokens
  printk: don't prefer unsuited consoles on registration
  printk: clean up recursion check related static variables
  namespacecheck: more kernel/printk.c fixes
  namespacecheck: fix kernel printk.c

Merge branch 'auto-ftrace-next' into tracing/for-linus

2008-07-14T14:11:52+00:00

Conflicts:

	arch/x86/kernel/entry_32.S
	arch/x86/kernel/process_32.c
	arch/x86/kernel/process_64.c
	arch/x86/lib/Makefile
	include/asm-x86/irqflags.h
	kernel/Makefile
	kernel/sched.c

Signed-off-by: Ingo Molnar

Merge branch 'linus' into x86/core

2008-07-12T05:29:02+00:00

Conflicts:

	arch/x86/mm/ioremap.c

Signed-off-by: Ingo Molnar