Hi Janis! :-)

[...]
 JK> If it fails to obtain the lock, it waits 
 JK> (sleeps, spins it's wheels) until the thread which holds the lock 
 JK> releases it.
The difference is exactly in the "sleeps, spins it's wheels"
part. A spinlock is a lock which you cannot sleep on, only busy-waiting in
a tight loop is allowed. A lock you can sleep on is called a semaphore - at
least those are the right terms when talking about the Linux kernel.

Spinlocks are used to synchronize between different interrupt handlers or
between interrupt handlers and normal kernel code - an interrupt handler
*cannot* sleep, therefore a semaphore would not work.

Ciao
Pascal

--- Msged/LNX 6.1.1