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hpilo: add locking comment

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Add explanation about lock nesting and purpose of each lock in hpilo.

Signed-off-by: David Altobelli <david.altobelli@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
David Altobelli 2009-09-18 12:46:26 -07:00 committed by Greg Kroah-Hartman
parent d71cb81af3
commit 68ea809af4
1 changed files with 12 additions and 1 deletions
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13
drivers/misc/hpilo.h
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@ -44,9 +44,20 @@ struct ilo_hwinfo {
struct pci_dev *ilo_dev;
/*
* open_lock serializes ccb_cnt during open and close
* [ irq disabled ]
* -> alloc_lock used when adding/removing/searching ccb_alloc,
* which represents all ccbs open on the device
* --> fifo_lock controls access to fifo queues shared with hw
*
* Locks must be taken in this order, but open_lock and alloc_lock
* are optional, they do not need to be held in order to take a
* lower level lock.
*/
spinlock_t open_lock;
spinlock_t alloc_lock;
spinlock_t fifo_lock;
spinlock_t open_lock;
struct cdev cdev;
};