design with spin_locks

["anubhav rakshit" <anubhavrocks@xxxxxxxxx>]

I am writing a driver,it has a data structure which is modified in both
interrupt context and user context.My current design is some thing like this:

struct shared_data;

interrupt_context{
                            spin_lock_irqsave(&xxx_lock,flags);
                                 ....modify shared_data....
                            spin_unlock_irqrestore(&xxx_lock, flags);

}

user_context{
                            spin_lock_irqsave(&xxx_lock,flags);
                                 ....modify shared_data....
                            spin_unlock_irqrestore(&xxx_lock, flags);
}


Now when user_context has the ability to sleep,i am wondering if there
is a way to
safely sleep in the user context while waiting for the spinlock to be
released by the interrupt_context?Something like this

interrupt_context{
                            spin_lock_irqsave(&xxx_lock,flags);
                                 ....modify shared_data....
                            spin_unlock_irqrestore(&xxx_lock, flags);
                            wake_up_interruptible(&wait_queue);
}



user_context{

                           if(wait_event_interruptible(&wait_queue,\

spin_trylock_irqsave(&xxx_lock,flags))
                               return -ERESTARTSYS;
                                 ....modify shared_data....
                            spin_unlock_irqrestore(&xxx_lock, flags);
}


Here the function spin_trylock_irqsave() will try to grab the spinlock
if it succeeds it returns true and behaves just like
spin_lock_irqsave(),if  it is unable to grab the spinlock,the function
returns false and the process is put to sleep.
This way i dont waste cpu cycles,by spinning uselessly.Is this
possible and will it be more efficient than the previous case?




--
Anubhav Rakshit

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