IRQ: Maintain regs pointer globally rather than passing to IRQ handlers

Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.

The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around.  On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).

Where appropriate, an arch may override the generic storage facility and do
something different with the variable.  On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.

Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions.  Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller.  A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.

I've build this code with allyesconfig for x86_64 and i386.  I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.

This will affect all archs.  Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:

	struct pt_regs *old_regs = set_irq_regs(regs);

And put the old one back at the end:

	set_irq_regs(old_regs);

Don't pass regs through to generic_handle_irq() or __do_IRQ().

In timer_interrupt(), this sort of change will be necessary:

	-	update_process_times(user_mode(regs));
	-	profile_tick(CPU_PROFILING, regs);
	+	update_process_times(user_mode(get_irq_regs()));
	+	profile_tick(CPU_PROFILING);

I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().

Some notes on the interrupt handling in the drivers:

 (*) input_dev() is now gone entirely.  The regs pointer is no longer stored in
     the input_dev struct.

 (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking.  It does
     something different depending on whether it's been supplied with a regs
     pointer or not.

 (*) Various IRQ handler function pointers have been moved to type
     irq_handler_t.

Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)

16 files changed, 24 insertions, 27 deletions

diff --git a/sound/isa/ad1816a/ad1816a_lib.c b/sound/isa/ad1816a/ad1816a_lib.c
index fd9b61e..b524e0d 100644
--- a/sound/isa/ad1816a/ad1816a_lib.c
+++ b/sound/isa/ad1816a/ad1816a_lib.c
@@ -315,7 +315,7 @@ static snd_pcm_uframes_t snd_ad1816a_capture_pointer(struct snd_pcm_substream *s
 }
 
 
-static irqreturn_t snd_ad1816a_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t snd_ad1816a_interrupt(int irq, void *dev_id)
 {
 	struct snd_ad1816a *chip = dev_id;
 	unsigned char status;
diff --git a/sound/isa/ad1848/ad1848_lib.c b/sound/isa/ad1848/ad1848_lib.c
index a6fbd5d..666b3bc 100644
--- a/sound/isa/ad1848/ad1848_lib.c
+++ b/sound/isa/ad1848/ad1848_lib.c
@@ -583,7 +583,7 @@ static int snd_ad1848_capture_prepare(struct snd_pcm_substream *substream)
 	return 0;
 }
 
-static irqreturn_t snd_ad1848_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t snd_ad1848_interrupt(int irq, void *dev_id)
 {
 	struct snd_ad1848 *chip = dev_id;
 
diff --git a/sound/isa/cs423x/cs4231_lib.c b/sound/isa/cs423x/cs4231_lib.c
index fbb2017..75c7c5f 100644
--- a/sound/isa/cs423x/cs4231_lib.c
+++ b/sound/isa/cs423x/cs4231_lib.c
@@ -920,7 +920,7 @@ static void snd_cs4231_overrange(struct snd_cs4231 *chip)
 		chip->capture_substream->runtime->overrange++;
 }
 
-irqreturn_t snd_cs4231_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+irqreturn_t snd_cs4231_interrupt(int irq, void *dev_id)
 {
 	struct snd_cs4231 *chip = dev_id;
 	unsigned char status;
diff --git a/sound/isa/es1688/es1688_lib.c b/sound/isa/es1688/es1688_lib.c
index 7e985d3..a2ab99f 100644
--- a/sound/isa/es1688/es1688_lib.c
+++ b/sound/isa/es1688/es1688_lib.c
@@ -479,7 +479,7 @@ static int snd_es1688_capture_trigger(struct snd_pcm_substream *substream,
 	return snd_es1688_trigger(chip, cmd, 0x0f);
 }
 
-static irqreturn_t snd_es1688_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t snd_es1688_interrupt(int irq, void *dev_id)
 {
 	struct snd_es1688 *chip = dev_id;
 
diff --git a/sound/isa/es18xx.c b/sound/isa/es18xx.c
index 8581820..2398d2c 100644
--- a/sound/isa/es18xx.c
+++ b/sound/isa/es18xx.c
@@ -754,7 +754,7 @@ static int snd_es18xx_playback_trigger(struct snd_pcm_substream *substream,
 		return snd_es18xx_playback2_trigger(chip, substream, cmd);
 }
 
-static irqreturn_t snd_es18xx_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t snd_es18xx_interrupt(int irq, void *dev_id)
 {
 	struct snd_es18xx *chip = dev_id;
 	unsigned char status;
@@ -799,7 +799,7 @@ static irqreturn_t snd_es18xx_interrupt(int irq, void *dev_id, struct pt_regs *r
 
 	/* MPU */
 	if ((status & MPU_IRQ) && chip->rmidi)
-		snd_mpu401_uart_interrupt(irq, chip->rmidi->private_data, regs);
+		snd_mpu401_uart_interrupt(irq, chip->rmidi->private_data);
 
 	/* Hardware volume */
 	if (status & HWV_IRQ) {
diff --git a/sound/isa/gus/gus_irq.c b/sound/isa/gus/gus_irq.c
index 42db375..537d3cf 100644
--- a/sound/isa/gus/gus_irq.c
+++ b/sound/isa/gus/gus_irq.c
@@ -30,7 +30,7 @@
 #define STAT_ADD(x)	while (0) { ; }
 #endif
 
-irqreturn_t snd_gus_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+irqreturn_t snd_gus_interrupt(int irq, void *dev_id)
 {
 	struct snd_gus_card * gus = dev_id;
 	unsigned char status;
diff --git a/sound/isa/gus/gusmax.c b/sound/isa/gus/gusmax.c
index ac11cae..52498c9 100644
--- a/sound/isa/gus/gusmax.c
+++ b/sound/isa/gus/gusmax.c
@@ -105,7 +105,7 @@ static int __init snd_gusmax_detect(struct snd_gus_card * gus)
 	return 0;
 }
 
-static irqreturn_t snd_gusmax_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t snd_gusmax_interrupt(int irq, void *dev_id)
 {
 	struct snd_gusmax *maxcard = (struct snd_gusmax *) dev_id;
 	int loop, max = 5;
@@ -115,12 +115,12 @@ static irqreturn_t snd_gusmax_interrupt(int irq, void *dev_id, struct pt_regs *r
 		loop = 0;
 		if (inb(maxcard->gus_status_reg)) {
 			handled = 1;
-			snd_gus_interrupt(irq, maxcard->gus, regs);
+			snd_gus_interrupt(irq, maxcard->gus);
 			loop++;
 		}
 		if (inb(maxcard->pcm_status_reg) & 0x01) { /* IRQ bit is set? */
 			handled = 1;
-			snd_cs4231_interrupt(irq, maxcard->cs4231, regs);
+			snd_cs4231_interrupt(irq, maxcard->cs4231);
 			loop++;
 		}
 	} while (loop && --max > 0);
diff --git a/sound/isa/gus/interwave.c b/sound/isa/gus/interwave.c
index ea69f25..5c474b8 100644
--- a/sound/isa/gus/interwave.c
+++ b/sound/isa/gus/interwave.c
@@ -299,7 +299,7 @@ static int __devinit snd_interwave_detect(struct snd_interwave *iwcard,
 	return -ENODEV;
 }
 
-static irqreturn_t snd_interwave_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t snd_interwave_interrupt(int irq, void *dev_id)
 {
 	struct snd_interwave *iwcard = (struct snd_interwave *) dev_id;
 	int loop, max = 5;
@@ -309,12 +309,12 @@ static irqreturn_t snd_interwave_interrupt(int irq, void *dev_id, struct pt_regs
 		loop = 0;
 		if (inb(iwcard->gus_status_reg)) {
 			handled = 1;
-			snd_gus_interrupt(irq, iwcard->gus, regs);
+			snd_gus_interrupt(irq, iwcard->gus);
 			loop++;
 		}
 		if (inb(iwcard->pcm_status_reg) & 0x01) {	/* IRQ bit is set? */
 			handled = 1;
-			snd_cs4231_interrupt(irq, iwcard->cs4231, regs);
+			snd_cs4231_interrupt(irq, iwcard->cs4231);
 			loop++;
 		}
 	} while (loop && --max > 0);
diff --git a/sound/isa/opl3sa2.c b/sound/isa/opl3sa2.c
index da92bf6..419b4eb 100644
--- a/sound/isa/opl3sa2.c
+++ b/sound/isa/opl3sa2.c
@@ -294,7 +294,7 @@ static int __devinit snd_opl3sa2_detect(struct snd_opl3sa2 *chip)
 	return 0;
 }
 
-static irqreturn_t snd_opl3sa2_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t snd_opl3sa2_interrupt(int irq, void *dev_id)
 {
 	unsigned short status;
 	struct snd_opl3sa2 *chip = dev_id;
@@ -312,12 +312,12 @@ static irqreturn_t snd_opl3sa2_interrupt(int irq, void *dev_id, struct pt_regs *
 
 	if ((status & 0x10) && chip->rmidi != NULL) {
 		handled = 1;
-		snd_mpu401_uart_interrupt(irq, chip->rmidi->private_data, regs);
+		snd_mpu401_uart_interrupt(irq, chip->rmidi->private_data);
 	}
 
 	if (status & 0x07) {	/* TI,CI,PI */
 		handled = 1;
-		snd_cs4231_interrupt(irq, chip->cs4231, regs);
+		snd_cs4231_interrupt(irq, chip->cs4231);
 	}
 
 	if (status & 0x40) { /* hardware volume change */
diff --git a/sound/isa/opti9xx/opti92x-ad1848.c b/sound/isa/opti9xx/opti92x-ad1848.c
index 9d528ae..a1ad39a 100644
--- a/sound/isa/opti9xx/opti92x-ad1848.c
+++ b/sound/isa/opti9xx/opti92x-ad1848.c
@@ -1090,7 +1090,7 @@ static void snd_opti93x_overrange(struct snd_opti93x *chip)
 	spin_unlock_irqrestore(&chip->lock, flags);
 }
 
-static irqreturn_t snd_opti93x_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t snd_opti93x_interrupt(int irq, void *dev_id)
 {
 	struct snd_opti93x *codec = dev_id;
 	unsigned char status;
diff --git a/sound/isa/sb/es968.c b/sound/isa/sb/es968.c
index d4d65b8..d4b2187 100644
--- a/sound/isa/sb/es968.c
+++ b/sound/isa/sb/es968.c
@@ -70,8 +70,7 @@ MODULE_DEVICE_TABLE(pnp_card, snd_es968_pnpids);
 
 #define	DRIVER_NAME	"snd-card-es968"
 
-static irqreturn_t snd_card_es968_interrupt(int irq, void *dev_id,
-					    struct pt_regs *regs)
+static irqreturn_t snd_card_es968_interrupt(int irq, void *dev_id)
 {
 	struct snd_sb *chip = dev_id;
 
diff --git a/sound/isa/sb/sb16_main.c b/sound/isa/sb/sb16_main.c
index f183f18..383911b 100644
--- a/sound/isa/sb/sb16_main.c
+++ b/sound/isa/sb/sb16_main.c
@@ -395,7 +395,7 @@ static int snd_sb16_capture_trigger(struct snd_pcm_substream *substream,
 	return result;
 }
 
-irqreturn_t snd_sb16dsp_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+irqreturn_t snd_sb16dsp_interrupt(int irq, void *dev_id)
 {
 	struct snd_sb *chip = dev_id;
 	unsigned char status;
@@ -405,7 +405,7 @@ irqreturn_t snd_sb16dsp_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 	status = snd_sbmixer_read(chip, SB_DSP4_IRQSTATUS);
 	spin_unlock(&chip->mixer_lock);
 	if ((status & SB_IRQTYPE_MPUIN) && chip->rmidi_callback)
-		chip->rmidi_callback(irq, chip->rmidi->private_data, regs);
+		chip->rmidi_callback(irq, chip->rmidi->private_data);
 	if (status & SB_IRQTYPE_8BIT) {
 		ok = 0;
 		if (chip->mode & SB_MODE_PLAYBACK_8) {
diff --git a/sound/isa/sb/sb8.c b/sound/isa/sb/sb8.c
index 141400c..268ebd3 100644
--- a/sound/isa/sb/sb8.c
+++ b/sound/isa/sb/sb8.c
@@ -63,7 +63,7 @@ struct snd_sb8 {
 	struct snd_sb *chip;
 };
 
-static irqreturn_t snd_sb8_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t snd_sb8_interrupt(int irq, void *dev_id)
 {
 	struct snd_sb *chip = dev_id;
 
diff --git a/sound/isa/sb/sb_common.c b/sound/isa/sb/sb_common.c
index f17de2b..c62a9e3 100644
--- a/sound/isa/sb/sb_common.c
+++ b/sound/isa/sb/sb_common.c
@@ -205,7 +205,7 @@ static int snd_sbdsp_dev_free(struct snd_device *device)
 int snd_sbdsp_create(struct snd_card *card,
 		     unsigned long port,
 		     int irq,
-		     irqreturn_t (*irq_handler)(int, void *, struct pt_regs *),
+		     irq_handler_t irq_handler,
 		     int dma8,
 		     int dma16,
 		     unsigned short hardware,
diff --git a/sound/isa/sgalaxy.c b/sound/isa/sgalaxy.c
index 8742fa5..4fcd0f4 100644
--- a/sound/isa/sgalaxy.c
+++ b/sound/isa/sgalaxy.c
@@ -109,7 +109,7 @@ static int __init snd_sgalaxy_sbdsp_command(unsigned long port, unsigned char va
 	return 0;
 }
 
-static irqreturn_t snd_sgalaxy_dummy_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t snd_sgalaxy_dummy_interrupt(int irq, void *dev_id)
 {
 	return IRQ_NONE;
 }
diff --git a/sound/isa/wavefront/wavefront.c b/sound/isa/wavefront/wavefront.c
index a8f8d2f..85db535 100644
--- a/sound/isa/wavefront/wavefront.c
+++ b/sound/isa/wavefront/wavefront.c
@@ -263,9 +263,7 @@ snd_wavefront_pnp (int dev, snd_wavefront_card_t *acard, struct pnp_card_link *c
 
 #endif /* CONFIG_PNP */
 
-static irqreturn_t snd_wavefront_ics2115_interrupt(int irq, 
-					    void *dev_id, 
-					    struct pt_regs *regs)
+static irqreturn_t snd_wavefront_ics2115_interrupt(int irq, void *dev_id)
 {
 	snd_wavefront_card_t *acard;