[POWERPC] Fix device-tree locking vs. interrupts

Browse source

Lockdep found out that we can occasionally take the device-tree
lock for reading from softirq time (from rtas_token called
by the rtas real time clock code called by the NTP code),
while we take it occasionally for writing without masking
interrupts. The combination of those two can thus deadlock.

While some of those cases of interrupt read lock could be fixed
(such as caching the RTAS tokens) I figured that taking the
lock for writing is so rare (device-tree modification) that we
may as well penalize that case and allow reading from interrupts.

Thus, this turns all the writers to take the lock with irqs
masked to avoid the situation.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

...

This commit is contained in:

Benjamin Herrenschmidt 2008-04-09 17:21:36 +10:00 • committed by Paul Mackerras

parent f13f4ca803

commit f4ac7b5eb7

1 changed files with 17 additions and 11 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

28

arch/powerpc/kernel/prom.c

View file