Search notes:
Kernel lock: spinlock
A spinlock is a simple single-holder lock. If the lock can not be acquired, the process keeps trying (=spinning) until it is possible.
Spinlocks are small, fast and can be used anywhere.
spinlock_t the_lock;
spinlock_init(&the_lock);
spin_lock(&the_lock);
do_something();
do_more();
spin_unlock(&the_lock);
CONFIG_SMP and CONFIG_PREEMPT
Kernels without
CONFIG_SMP and
CONFIG_PREEMPT do not have spinlocks because no other process can run at the sime time anyway.