Covert leds_list_lock to a rw_sempahore to match previous LED trigger
locking fixes, fixing lock ordering.
Signed-off-by: NRichard Purdie <rpurdie@rpsys.net>

Convert part of the led trigger core from rw spinlocks to rw
semaphores. We're calling functions which can sleep from invalid
contexts otherwise. Fixes bug #9264.
Signed-off-by: NRichard Purdie <rpurdie@rpsys.net>

Convert the LEDs class from struct class_device to struct device
since class_device is scheduled for removal.
Signed-off-by: NRichard Purdie <rpurdie@rpsys.net>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>

Add warning printks if led_trigger_register_simple() fails.
Signed-off-by: NRichard Purdie <rpurdie@rpsys.net>

Fix led_trigger_unregister_simple to handle the case where
led_trigger_register_simple fails, avoiding a NULL pointer
dereference.
Signed-off-by: NRichard Purdie <rpurdie@rpsys.net>

I was playing with LED triggers when I noticed that changing from heartbeat
(or ide-disk) to "none" at the right moment would leave the LED stuck on.
This is easy to reproduce by doing "find / >/dev/null" with the ide-disk
trigger enabled and then switching to "none".

Here is a patch that fixes the problem by explicitly turning the LED off
after removing the existing trigger.
Signed-off-by: NPaul Collins <paul@ondioline.org>
Acked-by: NRichard Purdie <rpurdie@rpsys.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NJörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

locking init cleanups:

 - convert " = SPIN_LOCK_UNLOCKED" to spin_lock_init() or DEFINE_SPINLOCK()
 - convert rwlocks in a similar manner

this patch was generated automatically.

Motivation:

 - cleanliness
 - lockdep needs control of lock initialization, which the open-coded
   variants do not give
 - it's also useful for -rt and for lock debugging in general
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add support for LED triggers to the LED subsystem.  "Triggers" are events
which change the state of an LED.  Two kinds of trigger are available, simple
ones which can be added to exising code with minimum disruption and complex
ones for implementing new or more complex functionality.
Signed-off-by: NRichard Purdie <rpurdie@rpsys.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>