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>
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04287f975e
Коммит
3eac4abaa6
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@ -143,13 +143,14 @@ void __sched __down_read(struct rw_semaphore *sem)
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{
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struct rwsem_waiter waiter;
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struct task_struct *tsk;
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unsigned long flags;
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spin_lock_irq(&sem->wait_lock);
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spin_lock_irqsave(&sem->wait_lock, flags);
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if (sem->activity >= 0 && list_empty(&sem->wait_list)) {
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/* granted */
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sem->activity++;
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spin_unlock_irq(&sem->wait_lock);
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spin_unlock_irqrestore(&sem->wait_lock, flags);
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goto out;
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}
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@ -164,7 +165,7 @@ void __sched __down_read(struct rw_semaphore *sem)
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list_add_tail(&waiter.list, &sem->wait_list);
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/* we don't need to touch the semaphore struct anymore */
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spin_unlock_irq(&sem->wait_lock);
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spin_unlock_irqrestore(&sem->wait_lock, flags);
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/* wait to be given the lock */
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for (;;) {
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@ -209,13 +210,14 @@ void __sched __down_write_nested(struct rw_semaphore *sem, int subclass)
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{
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struct rwsem_waiter waiter;
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struct task_struct *tsk;
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unsigned long flags;
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spin_lock_irq(&sem->wait_lock);
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spin_lock_irqsave(&sem->wait_lock, flags);
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if (sem->activity == 0 && list_empty(&sem->wait_list)) {
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/* granted */
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sem->activity = -1;
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spin_unlock_irq(&sem->wait_lock);
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spin_unlock_irqrestore(&sem->wait_lock, flags);
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goto out;
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}
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@ -230,7 +232,7 @@ void __sched __down_write_nested(struct rw_semaphore *sem, int subclass)
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list_add_tail(&waiter.list, &sem->wait_list);
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/* we don't need to touch the semaphore struct anymore */
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spin_unlock_irq(&sem->wait_lock);
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spin_unlock_irqrestore(&sem->wait_lock, flags);
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/* wait to be given the lock */
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for (;;) {
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