tree dea63b1eb9ce709790e9fd97cbefd130ed3403b5
parent 4c89d86b4df8e4f2cdccb72495e2f4664118ebf1
author Hendrik Brueckner <brueckner@linux.vnet.ibm.com> 1253075843 +0000
committer David S. Miller <davem@davemloft.net> 1253159851 -0700

iucv: fix iucv_buffer_cpumask check when calling IUCV functions

Prior to calling IUCV functions, the DECLARE BUFFER function must have been
called for at least one CPU to receive IUCV interrupts.

With commit "iucv: establish reboot notifier" (6c005961), a check has been
introduced to avoid calling IUCV functions if the current CPU does not have
an interrupt buffer declared.
Because one interrupt buffer is sufficient, change the condition to ensure
that one interrupt buffer is available.

In addition, checking the buffer on the current CPU creates a race with
CPU up/down notifications: before checking the buffer, the IUCV function
might be interrupted by an smp_call_function() that retrieves the interrupt
buffer for the current CPU.
When the IUCV function continues, the check fails and -EIO is returned. If a
buffer is available on any other CPU, the IUCV function call must be invoked
(instead of failing with -EIO).

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>