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| author | Thomas Zimmermann <tzimmermann@suse.de> | 2018-07-31 13:06:57 +0200 |
|---|---|---|
| committer | Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> | 2018-07-31 13:06:57 +0200 |
| commit | 56e6c104e4f151e19eb410004405ec52b4f8605a (patch) | |
| tree | ae7567c188e3306e7cc02bcd6db5f9025edef48b /kernel/printk | |
| parent | cb782a3fa952478177341e67275885ae52340f99 (diff) | |
| download | lwn-56e6c104e4f151e19eb410004405ec52b4f8605a.tar.gz lwn-56e6c104e4f151e19eb410004405ec52b4f8605a.zip | |
console: Replace #if 0 with atomic var 'ignore_console_lock_warning'
The macro WARN_CONSOLE_UNLOCKED prints a warning when a thread enters
the console's critical section without having acquired the console
lock. The console lock can be ignored when debugging the console using
printk, but this makes WARN_CONSOLE_UNLOCKED generate unnecessary
warnings.
The variable ignore_console_lock_warning temporarily disables
WARN_CONSOLE_UNLOCKED. Developers interested in debugging the console's
critical sections should increment it before entering the CS and
decrement it after leaving the CS. Setting ignore_console_lock_warning
is only for debugging. Regular operation should not manipulate it.
Acknoledgements: This patch is based on an earlier version by Steven
Rostedt. The use of atomic increment/decrement was suggested by Petr
Mladek.
Link: http://lkml.kernel.org/r/717e6337-e7a6-7a92-1c1b-8929a25696b5@suse.de
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
[b.zolnierkie: use <linux/atomic.h>]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Diffstat (limited to 'kernel/printk')
| -rw-r--r-- | kernel/printk/printk.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 3f041e7cbfc9..7d32a86758cd 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -66,6 +66,9 @@ int console_printk[4] = { CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ }; +atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0); +EXPORT_SYMBOL(ignore_console_lock_warning); + /* * Low level drivers may need that to know if they can schedule in * their unblank() callback or not. So let's export it. |