Interrupts and spinlocks

The full locking API is:

void spin_lock(spinlock_t *lock);
The normal locking function

void spin_lock_irqsave(spinlock_t *lock,
                       unsigned long flags);
Disables interrupts, saves previous state
Note flags is passed "by value"

void spin_lock_irq(spinlock_t *lock);
Disables interrupts without saving state
Use when you know interrupts are enabled

void spin_lock_bh(spinlock_t *lock);
Only disables software interrupts