printk: release lockbuf_lock before calling console_trylock_for_printk()
authorJan Kara <jack@suse.cz>
Wed, 4 Jun 2014 23:11:35 +0000 (16:11 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 4 Jun 2014 23:54:16 +0000 (16:54 -0700)
commit608873cacb9d0d2811586fcc79a38b64eabd6d32
treea72babb6839139ec4aaefcacc2fa19690c668414
parentca1d432ad8a527fabc5c7ceed8526e3a28de121c
printk: release lockbuf_lock before calling console_trylock_for_printk()

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: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/printk/printk.c