rtl_mutex.c : possible add : rtl_wait_sleep_irqrestore ?

[Edouard TISSERANT <tissered@esstin.uhp-nancy.fr>]

In some kinds of communication (see ArbraCan driver in CanFestival
project, http://www.esstin.uhp-nancy.fr/~tissered/CanFestival/) it is
usefull to stop IRQs while entering in a wait queue, and allowing them
while sleeping.

This could be possible by adding a rtl_wait_sleep_irqrestore function
in rtl_mutex.c.

This would look like this:
------8<------8<------8<------8<------8<------8<------8<
int rtl_wait_sleep_irqrestore (rtl_wait_t *wait, spinlock_t *lock,
unsigned long irq_state)
{
	pthread_t self = pthread_self();
	struct rtl_wait_struct wait_struct;

	self->abort = &rtl_wait_abort;
	self->abortdata = wait;

	wait_struct.magic = RTL_WAIT_MAGIC;
	wait_struct.waiter = self;
	wait_struct.next = wait->queue;
	wait->queue = &wait_struct;
	wait->p_lock = lock;

	RTL_MARK_SUSPENDED (self);

	rtl_spin_unlock_irqrestore(lock, irq_state);

	return rtl_schedule();
}
------8<------8<------8<------8<------8<------8<------8<
And the associated macro:

------8<------8<------8<------8<------8<------8<------8<
#define rtl_wait_event(wq, condition)\
	do{\
		unsigned long irq_state;\
		rtl_spin_lock_irqsave(wq->p_lock, irq_state);\
		if(!condition){\
			do{\
				rtl_wait_sleep_irqrestore(wq, wq->p_lock, irq_state);\
				rtl_spin_lock_irqsave(wq->p_lock, irq_state);\
			}while(!condition);\
		}\
		rtl_spin_unlock_irqrestore(wq->p_lock, irq_state);\
	}while(0)
------8<------8<------8<------8<------8<------8<------8<

I use it in the last version of ArbraCan.c and I think it could be
usefull for everyone.

Thanks,

				Edouard TISSERANT