Revision 1fd684346d41f6be2487c161f60d03a7feb68911 authored by Rafael J. Wysocki on 19 January 2009, 19:57:36 UTC, committed by Jeff Garzik on 27 January 2009, 07:15:51 UTC
Some notebooks from HP have the problem that their BIOSes attempt to spin down hard drives before entering ACPI system states S4 and S5. This leads to a yo-yo effect during system power-off shutdown and the last phase of hibernation when the disk is first spun down by the kernel and then almost immediately turned on and off by the BIOS. This, in turn, may result in shortening the disk's life times. To prevent this from happening we can blacklist the affected systems using DMI information. Blacklist HP nx6310 that uses the AHCI driver. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
1 parent 2a6e58d
rwsem.c
/* rwsem.c: R/W semaphores: contention handling functions
*
* Written by David Howells (dhowells@redhat.com).
* Derived from arch/i386/kernel/semaphore.c
*/
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/module.h>
/*
* Initialize an rwsem:
*/
void __init_rwsem(struct rw_semaphore *sem, const char *name,
struct lock_class_key *key)
{
#ifdef CONFIG_DEBUG_LOCK_ALLOC
/*
* Make sure we are not reinitializing a held semaphore:
*/
debug_check_no_locks_freed((void *)sem, sizeof(*sem));
lockdep_init_map(&sem->dep_map, name, key, 0);
#endif
sem->count = RWSEM_UNLOCKED_VALUE;
spin_lock_init(&sem->wait_lock);
INIT_LIST_HEAD(&sem->wait_list);
}
EXPORT_SYMBOL(__init_rwsem);
struct rwsem_waiter {
struct list_head list;
struct task_struct *task;
unsigned int flags;
#define RWSEM_WAITING_FOR_READ 0x00000001
#define RWSEM_WAITING_FOR_WRITE 0x00000002
};
/*
* handle the lock release when processes blocked on it that can now run
* - if we come here from up_xxxx(), then:
* - the 'active part' of count (&0x0000ffff) reached 0 (but may have changed)
* - the 'waiting part' of count (&0xffff0000) is -ve (and will still be so)
* - there must be someone on the queue
* - the spinlock must be held by the caller
* - woken process blocks are discarded from the list after having task zeroed
* - writers are only woken if downgrading is false
*/
static inline struct rw_semaphore *
__rwsem_do_wake(struct rw_semaphore *sem, int downgrading)
{
struct rwsem_waiter *waiter;
struct task_struct *tsk;
struct list_head *next;
signed long oldcount, woken, loop;
if (downgrading)
goto dont_wake_writers;
/* if we came through an up_xxxx() call, we only only wake someone up
* if we can transition the active part of the count from 0 -> 1
*/
try_again:
oldcount = rwsem_atomic_update(RWSEM_ACTIVE_BIAS, sem)
- RWSEM_ACTIVE_BIAS;
if (oldcount & RWSEM_ACTIVE_MASK)
goto undo;
waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
/* try to grant a single write lock if there's a writer at the front
* of the queue - note we leave the 'active part' of the count
* incremented by 1 and the waiting part incremented by 0x00010000
*/
if (!(waiter->flags & RWSEM_WAITING_FOR_WRITE))
goto readers_only;
/* We must be careful not to touch 'waiter' after we set ->task = NULL.
* It is an allocated on the waiter's stack and may become invalid at
* any time after that point (due to a wakeup from another source).
*/
list_del(&waiter->list);
tsk = waiter->task;
smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
goto out;
/* don't want to wake any writers */
dont_wake_writers:
waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
if (waiter->flags & RWSEM_WAITING_FOR_WRITE)
goto out;
/* grant an infinite number of read locks to the readers at the front
* of the queue
* - note we increment the 'active part' of the count by the number of
* readers before waking any processes up
*/
readers_only:
woken = 0;
do {
woken++;
if (waiter->list.next == &sem->wait_list)
break;
waiter = list_entry(waiter->list.next,
struct rwsem_waiter, list);
} while (waiter->flags & RWSEM_WAITING_FOR_READ);
loop = woken;
woken *= RWSEM_ACTIVE_BIAS - RWSEM_WAITING_BIAS;
if (!downgrading)
/* we'd already done one increment earlier */
woken -= RWSEM_ACTIVE_BIAS;
rwsem_atomic_add(woken, sem);
next = sem->wait_list.next;
for (; loop > 0; loop--) {
waiter = list_entry(next, struct rwsem_waiter, list);
next = waiter->list.next;
tsk = waiter->task;
smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
}
sem->wait_list.next = next;
next->prev = &sem->wait_list;
out:
return sem;
/* undo the change to count, but check for a transition 1->0 */
undo:
if (rwsem_atomic_update(-RWSEM_ACTIVE_BIAS, sem) != 0)
goto out;
goto try_again;
}
/*
* wait for a lock to be granted
*/
static struct rw_semaphore __sched *
rwsem_down_failed_common(struct rw_semaphore *sem,
struct rwsem_waiter *waiter, signed long adjustment)
{
struct task_struct *tsk = current;
signed long count;
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
/* set up my own style of waitqueue */
spin_lock_irq(&sem->wait_lock);
waiter->task = tsk;
get_task_struct(tsk);
list_add_tail(&waiter->list, &sem->wait_list);
/* we're now waiting on the lock, but no longer actively read-locking */
count = rwsem_atomic_update(adjustment, sem);
/* if there are no active locks, wake the front queued process(es) up */
if (!(count & RWSEM_ACTIVE_MASK))
sem = __rwsem_do_wake(sem, 0);
spin_unlock_irq(&sem->wait_lock);
/* wait to be given the lock */
for (;;) {
if (!waiter->task)
break;
schedule();
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
}
tsk->state = TASK_RUNNING;
return sem;
}
/*
* wait for the read lock to be granted
*/
asmregparm struct rw_semaphore __sched *
rwsem_down_read_failed(struct rw_semaphore *sem)
{
struct rwsem_waiter waiter;
waiter.flags = RWSEM_WAITING_FOR_READ;
rwsem_down_failed_common(sem, &waiter,
RWSEM_WAITING_BIAS - RWSEM_ACTIVE_BIAS);
return sem;
}
/*
* wait for the write lock to be granted
*/
asmregparm struct rw_semaphore __sched *
rwsem_down_write_failed(struct rw_semaphore *sem)
{
struct rwsem_waiter waiter;
waiter.flags = RWSEM_WAITING_FOR_WRITE;
rwsem_down_failed_common(sem, &waiter, -RWSEM_ACTIVE_BIAS);
return sem;
}
/*
* handle waking up a waiter on the semaphore
* - up_read/up_write has decremented the active part of count if we come here
*/
asmregparm struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem)
{
unsigned long flags;
spin_lock_irqsave(&sem->wait_lock, flags);
/* do nothing if list empty */
if (!list_empty(&sem->wait_list))
sem = __rwsem_do_wake(sem, 0);
spin_unlock_irqrestore(&sem->wait_lock, flags);
return sem;
}
/*
* downgrade a write lock into a read lock
* - caller incremented waiting part of count and discovered it still negative
* - just wake up any readers at the front of the queue
*/
asmregparm struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem)
{
unsigned long flags;
spin_lock_irqsave(&sem->wait_lock, flags);
/* do nothing if list empty */
if (!list_empty(&sem->wait_list))
sem = __rwsem_do_wake(sem, 1);
spin_unlock_irqrestore(&sem->wait_lock, flags);
return sem;
}
EXPORT_SYMBOL(rwsem_down_read_failed);
EXPORT_SYMBOL(rwsem_down_write_failed);
EXPORT_SYMBOL(rwsem_wake);
EXPORT_SYMBOL(rwsem_downgrade_wake);
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