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authorKevin Hilman <khilman@deeprootsystems.com>2010-04-07 18:52:46 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2010-04-07 23:15:05 (GMT)
commit3eac4abaa69949af0e2f64e5c55ee8a22bbdd3e7 (patch)
tree9620ae3c39a0870a010a08166e29823a7afbf262 /lib/rwsem-spinlock.c
parent04287f975e68038051eb9c79896866d36610b8e0 (diff)
rwsem generic spinlock: use IRQ save/restore spinlocks
rwsems can be used with IRQs disabled, particularily in early boot before IRQs are enabled. Currently the spin_unlock_irq() usage in the slow-patch will unconditionally enable interrupts and cause problems since interrupts are not yet initialized or enabled. This patch uses save/restore versions of IRQ spinlocks in the slowpath to ensure interrupts are not unintentionally disabled. Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/rwsem-spinlock.c')
-rw-r--r--lib/rwsem-spinlock.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/lib/rwsem-spinlock.c b/lib/rwsem-spinlock.c
index ccf95bf..ffc9fc7 100644
--- a/lib/rwsem-spinlock.c
+++ b/lib/rwsem-spinlock.c
@@ -143,13 +143,14 @@ void __sched __down_read(struct rw_semaphore *sem)
{
struct rwsem_waiter waiter;
struct task_struct *tsk;
+ unsigned long flags;
- spin_lock_irq(&sem->wait_lock);
+ spin_lock_irqsave(&sem->wait_lock, flags);
if (sem->activity >= 0 && list_empty(&sem->wait_list)) {
/* granted */
sem->activity++;
- spin_unlock_irq(&sem->wait_lock);
+ spin_unlock_irqrestore(&sem->wait_lock, flags);
goto out;
}
@@ -164,7 +165,7 @@ void __sched __down_read(struct rw_semaphore *sem)
list_add_tail(&waiter.list, &sem->wait_list);
/* we don't need to touch the semaphore struct anymore */
- spin_unlock_irq(&sem->wait_lock);
+ spin_unlock_irqrestore(&sem->wait_lock, flags);
/* wait to be given the lock */
for (;;) {
@@ -209,13 +210,14 @@ void __sched __down_write_nested(struct rw_semaphore *sem, int subclass)
{
struct rwsem_waiter waiter;
struct task_struct *tsk;
+ unsigned long flags;
- spin_lock_irq(&sem->wait_lock);
+ spin_lock_irqsave(&sem->wait_lock, flags);
if (sem->activity == 0 && list_empty(&sem->wait_list)) {
/* granted */
sem->activity = -1;
- spin_unlock_irq(&sem->wait_lock);
+ spin_unlock_irqrestore(&sem->wait_lock, flags);
goto out;
}
@@ -230,7 +232,7 @@ void __sched __down_write_nested(struct rw_semaphore *sem, int subclass)
list_add_tail(&waiter.list, &sem->wait_list);
/* we don't need to touch the semaphore struct anymore */
- spin_unlock_irq(&sem->wait_lock);
+ spin_unlock_irqrestore(&sem->wait_lock, flags);
/* wait to be given the lock */
for (;;) {

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