Skip to main content

Browse the archive

https://github.com/torvalds/linux
05 April 2024, 19:05:47 UTC
Revision e8129c642155616d9e2160a75f103e127c8c3708 authored by Heiko Carstens on 25 November 2010, 08:52:45 UTC, committed by Martin Schwidefsky on 25 November 2010, 08:52:59 UTC 
[S390] nmi: fix clock comparator revalidation
 
On each machine check all registers are revalidated. The save area for
the clock comparator however only contains the upper most seven bytes
of the former contents, if valid.
Therefore the machine check handler uses a store clock instruction to
get the current time and writes that to the clock comparator register
which in turn will generate an immediate timer interrupt.
However within the lowcore the expected time of the next timer
interrupt is stored. If the interrupt happens before that time the
handler won't be called. In turn the clock comparator won't be
reprogrammed and therefore the interrupt condition stays pending which
causes an interrupt loop until the expected time is reached.

On NOHZ machines this can result in unresponsive machines since the
time of the next expected interrupted can be a couple of days in the
future.

To fix this just revalidate the clock comparator register with the
expected value.
In addition the special handling for udelay must be changed as well.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
1 parent 698fd6a
History
Tip revision: e8129c642155616d9e2160a75f103e127c8c3708 authored by Heiko Carstens on 25 November 2010, 08:52:45 UTC
[S390] nmi: fix clock comparator revalidation
Tip revision: e8129c6
File Mode Size
Documentation
arch
block
crypto
drivers
firmware
fs
include
init
ipc
kernel
lib
mm
net
samples
scripts
security
sound
tools
usr
virt
.gitignore -rw-r--r-- 936 bytes
.mailmap -rw-r--r-- 3.9 KB
COPYING -rw-r--r-- 18.3 KB
CREDITS -rw-r--r-- 91.8 KB
Kbuild -rw-r--r-- 2.4 KB
Kconfig -rw-r--r-- 252 bytes
MAINTAINERS -rw-r--r-- 178.4 KB
Makefile -rw-r--r-- 50.9 KB
README -rw-r--r-- 17.1 KB
REPORTING-BUGS -rw-r--r-- 3.3 KB

README

back to top