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authorBenjamin Herrenschmidt <benh@ozlabs.org>2008-04-09 17:21:36 +1000
committerPaul Mackerras <paulus@samba.org>2008-04-18 15:37:16 +1000
commitf4ac7b5eb79ef15819c966b1f6b84bf443949123 (patch)
treecfc81caaa2d1d50f0986c99cf59764060993eb60 /arch/powerpc/kernel/head_32.S
parentf13f4ca8036516ca1b99a41f95f7dea7e4dce104 (diff)
[POWERPC] Fix device-tree locking vs. interrupts
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>
Diffstat (limited to 'arch/powerpc/kernel/head_32.S')
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