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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2007-05-10 22:22:46 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-11 08:29:34 -0700
commit2d3fbbb391e280724f7f7804ab00ff61cf1b6a4c (patch)
tree218b942ae24cd22c7b8309a650d3e7273db3796c /include
parente1fa2e136ff64a3814a98c03d46320b9e80d29c8 (diff)
Add hard_irq_disable()
Some architectures, like powerpc, implement lazy disabling of interrupts. That means that on those, local_irq_disable() doesn't actually disable interrupts on the CPU, but only sets some per CPU flag which cause them to be disabled only if an interrupt actually occurs. However, in some cases, such as stop_machine, we really want interrupts to be fully disabled. For example, I have code using stop machine to do ECC error injection, used to verify operations of the ECC hardware, that sort of thing. It really needs to make sure that nothing is actually writing to memory while the injection happens. Similar examples can be found in other low level bits and pieces. This patch implements a generic hard_irq_disable() function which is meant to be called -after- local_irq_disable() and ensures that interrupts are fully disabled on that CPU. The default implementation is a nop, though powerpc does already provide an appropriate one. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/interrupt.h10
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index f7b01b9a35b..5323f627585 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -241,6 +241,16 @@ static inline void __deprecated save_and_cli(unsigned long *x)
#define save_and_cli(x) save_and_cli(&x)
#endif /* CONFIG_SMP */
+/* Some architectures might implement lazy enabling/disabling of
+ * interrupts. In some cases, such as stop_machine, we might want
+ * to ensure that after a local_irq_disable(), interrupts have
+ * really been disabled in hardware. Such architectures need to
+ * implement the following hook.
+ */
+#ifndef hard_irq_disable
+#define hard_irq_disable() do { } while(0)
+#endif
+
/* PLEASE, avoid to allocate new softirqs, if you need not _really_ high
frequency threaded job scheduling. For almost all the purposes
tasklets are more than enough. F.e. all serial device BHs et