tree d0b0d72691d4e2e3df0e9f4d2e335bebc378fdeb
parent c6f70d3b8a32fdec60d3f78cb59423f056f16688
author Martin Schwidefsky <schwidefsky@de.ibm.com> 1447927785 +0100
committer Martin Schwidefsky <schwidefsky@de.ibm.com> 1448612658 +0100

s390/spinlock: do not yield to a CPU in udelay/mdelay

It does not make sense to try to relinquish the time slice with diag 0x9c
to a CPU in a state that does not allow to schedule the CPU. The scenario
where this can happen is a CPU waiting in udelay/mdelay while holding a
spin-lock.

Add a CIF bit to tag a CPU in enabled wait and use it to detect that the
yield of a CPU will not be successful and skip the diagnose call.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>