[MIPS] SMTC: Instant IPI replay.
SMTC pseudo-interrupts between TCs are deferred and queued if the target
TC is interrupt-inhibited (IXMT). In the first SMTC prototypes, these
queued IPIs were serviced on return to user mode, or on entry into the
kernel idle loop. The INSTANT_REPLAY option dispatches them as part of
local_irq_restore() processing, which adds runtime overhead (hence the
option to turn it off), but ensures that IPIs are handled promptly even
under heavy I/O interrupt load.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/include/asm-mips/irqflags.h b/include/asm-mips/irqflags.h
index 46bf5de..af3b07d 100644
--- a/include/asm-mips/irqflags.h
+++ b/include/asm-mips/irqflags.h
@@ -15,6 +15,27 @@
#include <asm/hazards.h>
+/*
+ * CONFIG_MIPS_MT_SMTC_INSTANT_REPLAY does prompt replay of deferred IPIs,
+ * at the cost of branch and call overhead on each local_irq_restore()
+ */
+
+#ifdef CONFIG_MIPS_MT_SMTC_INSTANT_REPLAY
+
+extern void smtc_ipi_replay(void);
+
+#define irq_restore_epilog(flags) \
+do { \
+ if (!(flags & 0x0400)) \
+ smtc_ipi_replay(); \
+} while (0)
+
+#else
+
+#define irq_restore_epilog(ignore) do { } while (0)
+
+#endif /* CONFIG_MIPS_MT_SMTC_INSTANT_REPLAY */
+
__asm__ (
" .macro raw_local_irq_enable \n"
" .set push \n"
@@ -193,6 +214,7 @@
: "=r" (__tmp1) \
: "0" (flags) \
: "memory"); \
+ irq_restore_epilog(flags); \
} while(0)
static inline int raw_irqs_disabled_flags(unsigned long flags)