tree d7c62f412b1e99b2ebb5d37e8f86539b7dc03d9d
parent 9e280f6693083baf1b7741c2b820be8d4109509e
author Jan Glauber <jang@linux.vnet.ibm.com> 1311497307 +0200
committer Martin Schwidefsky <schwidefsky@de.ibm.com> 1311497302 +0200

[S390] race safe external interrupt registration

The (un-)register_external_interrupt functions are not race safe if
more than one interrupt handler is added or deleted for an external
interrupt concurrently.

Make the registration / unregistration of external interrupts race safe
by using RCU and a spinlock. RCU is used to avoid a performance penalty
in the external interrupt handler, the register and unregister functions
are protected by the spinlock and are not performance critical.
call_rcu must be used since the SCLP driver uses the interface with
IRQs disabled. Also use the generic list implementation rather than
homebrewn list code.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>