Merge branch 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus

* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus:
  [MIPS] Vr41xx: Fix after GENERIC_HARDIRQS_NO__DO_IRQ change
  [MIPS] SMTC: Instant IPI replay.

3 files changed, 56 insertions, 24 deletions

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index fd2ff0698a85..bbd386f572d9 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1568,6 +1568,20 @@ config MIPS_MT_FPAFF
 	depends on MIPS_MT
 	default y
 
+config MIPS_MT_SMTC_INSTANT_REPLAY
+	bool "Low-latency Dispatch of Deferred SMTC IPIs"
+	depends on MIPS_MT_SMTC
+	default y
+	help
+	  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.
+
 config MIPS_VPE_LOADER_TOM
 	bool "Load VPE program into memory hidden from linux"
 	depends on MIPS_VPE_LOADER
diff --git a/arch/mips/kernel/smtc.c b/arch/mips/kernel/smtc.c
index a8b387197d5b..44238ab2fc99 100644
--- a/arch/mips/kernel/smtc.c
+++ b/arch/mips/kernel/smtc.c
@@ -1017,6 +1017,33 @@ void setup_cross_vpe_interrupts(void)
  * SMTC-specific hacks invoked from elsewhere in the kernel.
  */
 
+void smtc_ipi_replay(void)
+{
+	/*
+	 * To the extent that we've ever turned interrupts off,
+	 * we may have accumulated deferred IPIs.  This is subtle.
+	 * If we use the smtc_ipi_qdepth() macro, we'll get an
+	 * exact number - but we'll also disable interrupts
+	 * and create a window of failure where a new IPI gets
+	 * queued after we test the depth but before we re-enable
+	 * interrupts. So long as IXMT never gets set, however,
+	 * we should be OK:  If we pick up something and dispatch
+	 * it here, that's great. If we see nothing, but concurrent
+	 * with this operation, another TC sends us an IPI, IXMT
+	 * is clear, and we'll handle it as a real pseudo-interrupt
+	 * and not a pseudo-pseudo interrupt.
+	 */
+	if (IPIQ[smp_processor_id()].depth > 0) {
+		struct smtc_ipi *pipi;
+		extern void self_ipi(struct smtc_ipi *);
+
+		while ((pipi = smtc_ipi_dq(&IPIQ[smp_processor_id()]))) {
+			self_ipi(pipi);
+			smtc_cpu_stats[smp_processor_id()].selfipis++;
+		}
+	}
+}
+
 void smtc_idle_loop_hook(void)
 {
 #ifdef SMTC_IDLE_HOOK_DEBUG
@@ -1113,29 +1140,14 @@ void smtc_idle_loop_hook(void)
 	if (pdb_msg != &id_ho_db_msg[0])
 		printk("CPU%d: %s", smp_processor_id(), id_ho_db_msg);
 #endif /* SMTC_IDLE_HOOK_DEBUG */
+
 	/*
-	 * To the extent that we've ever turned interrupts off,
-	 * we may have accumulated deferred IPIs.  This is subtle.
-	 * If we use the smtc_ipi_qdepth() macro, we'll get an
-	 * exact number - but we'll also disable interrupts
-	 * and create a window of failure where a new IPI gets
-	 * queued after we test the depth but before we re-enable
-	 * interrupts. So long as IXMT never gets set, however,
-	 * we should be OK:  If we pick up something and dispatch
-	 * it here, that's great. If we see nothing, but concurrent
-	 * with this operation, another TC sends us an IPI, IXMT
-	 * is clear, and we'll handle it as a real pseudo-interrupt
-	 * and not a pseudo-pseudo interrupt.
+	 * Replay any accumulated deferred IPIs. If "Instant Replay"
+	 * is in use, there should never be any.
 	 */
-	if (IPIQ[smp_processor_id()].depth > 0) {
-		struct smtc_ipi *pipi;
-		extern void self_ipi(struct smtc_ipi *);
-
-		if ((pipi = smtc_ipi_dq(&IPIQ[smp_processor_id()])) != NULL) {
-			self_ipi(pipi);
-			smtc_cpu_stats[smp_processor_id()].selfipis++;
-		}
-	}
+#ifndef CONFIG_MIPS_MT_SMTC_INSTANT_REPLAY
+	smtc_ipi_replay();
+#endif /* CONFIG_MIPS_MT_SMTC_INSTANT_REPLAY */
 }
 
 void smtc_soft_dump(void)
diff --git a/arch/mips/vr41xx/common/irq.c b/arch/mips/vr41xx/common/irq.c
index 397ba94cd7ec..16decf4ac2f4 100644
--- a/arch/mips/vr41xx/common/irq.c
+++ b/arch/mips/vr41xx/common/irq.c
@@ -1,7 +1,7 @@
 /*
  *  Interrupt handing routines for NEC VR4100 series.
  *
- *  Copyright (C) 2005  Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
+ *  Copyright (C) 2005-2007  Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -73,13 +73,19 @@ static void irq_dispatch(unsigned int irq)
 	if (cascade->get_irq != NULL) {
 		unsigned int source_irq = irq;
 		desc = irq_desc + source_irq;
-		desc->chip->ack(source_irq);
+		if (desc->chip->mask_ack)
+			desc->chip->mask_ack(source_irq);
+		else {
+			desc->chip->mask(source_irq);
+			desc->chip->ack(source_irq);
+		}
 		irq = cascade->get_irq(irq);
 		if (irq < 0)
 			atomic_inc(&irq_err_count);
 		else
 			irq_dispatch(irq);
-		desc->chip->end(source_irq);
+		if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
+			desc->chip->unmask(source_irq);
 	} else
 		do_IRQ(irq);
 }