spinlock

Finally, if your kernel thread shares data with a bottom half, then you can use another variant of the spinlock.

First you create a new spinlock through a simple declaration.

In this example, an array is created of spinlock_t with a size of LOCK_COUNT.

This version of the spinlock disables soft interrupts on the local CPU.

The spin_unlock_irqrestore function releases the spinlock and restores the interrupts (via the flags argument).

The task in the session is waiting for a spinlock to become free.

Make sure this copying happens inside the critical section by holding a spinlock.

The spin_lock_irqsave function acquires the spinlock and disables interrupts on the local processor (in the SMP case).

The spinlock is needed here, because the kernel thread will be running independently and will access the global structure.

Yes folks, there is a pseudo-spin lock and call to Threading. Sleep in there.

I've used a combination of mutexes and spinlocks to keep things synchronized.

Now that you have a spinlock defined, there are a number of locking variants that you can use.

There are also four ways to release a spinlock; the one you use must correspond to the function you used to take the lock

There are actually four functions that can lock a spinlock