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, 34 insertions, 42 deletions

diff --git a/drivers/net/irda/ali-ircc.c b/drivers/net/irda/ali-ircc.c
index 68d4c418cb9..971e2dee1e6 100644
--- a/drivers/net/irda/ali-ircc.c
+++ b/drivers/net/irda/ali-ircc.c
@@ -660,8 +660,7 @@ static int ali_ircc_read_dongle_id (int i, chipio_t *info)
  *    An interrupt from the chip has arrived. Time to do some work
  *
  */
-static irqreturn_t ali_ircc_interrupt(int irq, void *dev_id,
-					struct pt_regs *regs)
+static irqreturn_t ali_ircc_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *) dev_id;
 	struct ali_ircc_cb *self;
diff --git a/drivers/net/irda/au1k_ir.c b/drivers/net/irda/au1k_ir.c
index 7b2b4135bb2..37914dc5b90 100644
--- a/drivers/net/irda/au1k_ir.c
+++ b/drivers/net/irda/au1k_ir.c
@@ -51,7 +51,7 @@ static int au1k_irda_start(struct net_device *);
 static int au1k_irda_stop(struct net_device *dev);
 static int au1k_irda_hard_xmit(struct sk_buff *, struct net_device *);
 static int au1k_irda_rx(struct net_device *);
-static void au1k_irda_interrupt(int, void *, struct pt_regs *);
+static void au1k_irda_interrupt(int, void *);
 static void au1k_tx_timeout(struct net_device *);
 static struct net_device_stats *au1k_irda_stats(struct net_device *);
 static int au1k_irda_ioctl(struct net_device *, struct ifreq *, int);
@@ -627,7 +627,7 @@ static int au1k_irda_rx(struct net_device *dev)
 }
 
 
-void au1k_irda_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+void au1k_irda_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *) dev_id;
 
diff --git a/drivers/net/irda/donauboe.c b/drivers/net/irda/donauboe.c
index 33c07d5275d..7a9128181e6 100644
--- a/drivers/net/irda/donauboe.c
+++ b/drivers/net/irda/donauboe.c
@@ -709,7 +709,7 @@ stuff_byte (__u8 byte, __u8 * buf)
 }
 
 static irqreturn_t
-toshoboe_probeinterrupt (int irq, void *dev_id, struct pt_regs *regs)
+toshoboe_probeinterrupt (int irq, void *dev_id)
 {
   struct toshoboe_cb *self = (struct toshoboe_cb *) dev_id;
   __u8 irqstat;
@@ -1161,7 +1161,7 @@ dumpbufs(skb->data,skb->len,'>');
 
 /*interrupt handler */
 static irqreturn_t
-toshoboe_interrupt (int irq, void *dev_id, struct pt_regs *regs)
+toshoboe_interrupt (int irq, void *dev_id)
 {
   struct toshoboe_cb *self = (struct toshoboe_cb *) dev_id;
   __u8 irqstat;
diff --git a/drivers/net/irda/irda-usb.c b/drivers/net/irda/irda-usb.c
index 383cef1f599..14bda765c2f 100644
--- a/drivers/net/irda/irda-usb.c
+++ b/drivers/net/irda/irda-usb.c
@@ -114,9 +114,9 @@ static void irda_usb_change_speed_xbofs(struct irda_usb_cb *self);
 static int irda_usb_hard_xmit(struct sk_buff *skb, struct net_device *dev);
 static int irda_usb_open(struct irda_usb_cb *self);
 static void irda_usb_close(struct irda_usb_cb *self);
-static void speed_bulk_callback(struct urb *urb, struct pt_regs *regs);
-static void write_bulk_callback(struct urb *urb, struct pt_regs *regs);
-static void irda_usb_receive(struct urb *urb, struct pt_regs *regs);
+static void speed_bulk_callback(struct urb *urb);
+static void write_bulk_callback(struct urb *urb);
+static void irda_usb_receive(struct urb *urb);
 static void irda_usb_rx_defer_expired(unsigned long data);
 static int irda_usb_net_open(struct net_device *dev);
 static int irda_usb_net_close(struct net_device *dev);
@@ -343,7 +343,7 @@ static void irda_usb_change_speed_xbofs(struct irda_usb_cb *self)
  * Speed URB callback
  * Now, we can only get called for the speed URB.
  */
-static void speed_bulk_callback(struct urb *urb, struct pt_regs *regs)
+static void speed_bulk_callback(struct urb *urb)
 {
 	struct irda_usb_cb *self = urb->context;
 	
@@ -562,7 +562,7 @@ drop:
 /*
  * Note : this function will be called only for tx_urb...
  */
-static void write_bulk_callback(struct urb *urb, struct pt_regs *regs)
+static void write_bulk_callback(struct urb *urb)
 {
 	unsigned long flags;
 	struct sk_buff *skb = urb->context;
@@ -809,7 +809,7 @@ static void irda_usb_submit(struct irda_usb_cb *self, struct sk_buff *skb, struc
  *     Called by the USB subsystem when a frame has been received
  *
  */
-static void irda_usb_receive(struct urb *urb, struct pt_regs *regs)
+static void irda_usb_receive(struct urb *urb)
 {
 	struct sk_buff *skb = (struct sk_buff *) urb->context;
 	struct irda_usb_cb *self; 
diff --git a/drivers/net/irda/irport.c b/drivers/net/irda/irport.c
index ba4f3eb988b..6ea78ececca 100644
--- a/drivers/net/irda/irport.c
+++ b/drivers/net/irda/irport.c
@@ -87,8 +87,7 @@ static struct net_device_stats *irport_net_get_stats(struct net_device *dev);
 static int irport_change_speed_complete(struct irda_task *task);
 static void irport_timeout(struct net_device *dev);
 
-static irqreturn_t irport_interrupt(int irq, void *dev_id,
-				    struct pt_regs *regs);
+static irqreturn_t irport_interrupt(int irq, void *dev_id);
 static int irport_hard_xmit(struct sk_buff *skb, struct net_device *dev);
 static void irport_change_speed(void *priv, __u32 speed);
 static int irport_net_open(struct net_device *dev);
@@ -761,12 +760,11 @@ static inline void irport_receive(struct irport_cb *self)
 }
 
 /*
- * Function irport_interrupt (irq, dev_id, regs)
+ * Function irport_interrupt (irq, dev_id)
  *
  *    Interrupt handler
  */
-static irqreturn_t irport_interrupt(int irq, void *dev_id,
-				    struct pt_regs *regs) 
+static irqreturn_t irport_interrupt(int irq, void *dev_id) 
 {
 	struct net_device *dev = (struct net_device *) dev_id;
 	struct irport_cb *self;
diff --git a/drivers/net/irda/irport.h b/drivers/net/irda/irport.h
index fc89c8c3dd7..4393168347e 100644
--- a/drivers/net/irda/irport.h
+++ b/drivers/net/irda/irport.h
@@ -74,7 +74,7 @@ struct irport_cb {
 	/* For piggyback drivers */
 	void *priv;                
 	void (*change_speed)(void *priv, __u32 speed);
-	int (*interrupt)(int irq, void *dev_id, struct pt_regs *regs);
+	int (*interrupt)(int irq, void *dev_id);
 };
 
 #endif /* IRPORT_H */
diff --git a/drivers/net/irda/mcs7780.c b/drivers/net/irda/mcs7780.c
index 415ba8dc94c..b32c52ed19d 100644
--- a/drivers/net/irda/mcs7780.c
+++ b/drivers/net/irda/mcs7780.c
@@ -764,7 +764,7 @@ static struct net_device_stats *mcs_net_get_stats(struct net_device *netdev)
 }
 
 /* Receive callback function.  */
-static void mcs_receive_irq(struct urb *urb, struct pt_regs *regs)
+static void mcs_receive_irq(struct urb *urb)
 {
 	__u8 *bytes;
 	struct mcs_cb *mcs = urb->context;
@@ -813,7 +813,7 @@ static void mcs_receive_irq(struct urb *urb, struct pt_regs *regs)
 }
 
 /* Transmit callback funtion.  */
-static void mcs_send_irq(struct urb *urb, struct pt_regs *regs)
+static void mcs_send_irq(struct urb *urb)
 {
 	struct mcs_cb *mcs = urb->context;
 	struct net_device *ndev = mcs->netdev;
diff --git a/drivers/net/irda/mcs7780.h b/drivers/net/irda/mcs7780.h
index 1a723d725c2..b18148cee63 100644
--- a/drivers/net/irda/mcs7780.h
+++ b/drivers/net/irda/mcs7780.h
@@ -156,8 +156,8 @@ static int mcs_net_close(struct net_device *netdev);
 static int mcs_net_open(struct net_device *netdev);
 static struct net_device_stats *mcs_net_get_stats(struct net_device *netdev);
 
-static void mcs_receive_irq(struct urb *urb, struct pt_regs *regs);
-static void mcs_send_irq(struct urb *urb, struct pt_regs *regs);
+static void mcs_receive_irq(struct urb *urb);
+static void mcs_send_irq(struct urb *urb);
 static int mcs_hard_xmit(struct sk_buff *skb, struct net_device *netdev);
 
 static int mcs_probe(struct usb_interface *intf,
diff --git a/drivers/net/irda/nsc-ircc.c b/drivers/net/irda/nsc-ircc.c
index 7185a4ee3c1..ea12e999814 100644
--- a/drivers/net/irda/nsc-ircc.c
+++ b/drivers/net/irda/nsc-ircc.c
@@ -2066,8 +2066,7 @@ static void nsc_ircc_fir_interrupt(struct nsc_ircc_cb *self, int iobase,
  *    An interrupt from the chip has arrived. Time to do some work
  *
  */
-static irqreturn_t nsc_ircc_interrupt(int irq, void *dev_id,
-				struct pt_regs *regs)
+static irqreturn_t nsc_ircc_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *) dev_id;
 	struct nsc_ircc_cb *self;
diff --git a/drivers/net/irda/pxaficp_ir.c b/drivers/net/irda/pxaficp_ir.c
index afb19e8d95c..f9a1c88a428 100644
--- a/drivers/net/irda/pxaficp_ir.c
+++ b/drivers/net/irda/pxaficp_ir.c
@@ -199,7 +199,7 @@ static int pxa_irda_set_speed(struct pxa_irda *si, int speed)
 }
 
 /* SIR interrupt service routine. */
-static irqreturn_t pxa_irda_sir_irq(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t pxa_irda_sir_irq(int irq, void *dev_id)
 {
 	struct net_device *dev = dev_id;
 	struct pxa_irda *si = netdev_priv(dev);
@@ -281,7 +281,7 @@ static irqreturn_t pxa_irda_sir_irq(int irq, void *dev_id, struct pt_regs *regs)
 }
 
 /* FIR Receive DMA interrupt handler */
-static void pxa_irda_fir_dma_rx_irq(int channel, void *data, struct pt_regs *regs)
+static void pxa_irda_fir_dma_rx_irq(int channel, void *data)
 {
 	int dcsr = DCSR(channel);
 
@@ -291,7 +291,7 @@ static void pxa_irda_fir_dma_rx_irq(int channel, void *data, struct pt_regs *reg
 }
 
 /* FIR Transmit DMA interrupt handler */
-static void pxa_irda_fir_dma_tx_irq(int channel, void *data, struct pt_regs *regs)
+static void pxa_irda_fir_dma_tx_irq(int channel, void *data)
 {
 	struct net_device *dev = data;
 	struct pxa_irda *si = netdev_priv(dev);
@@ -388,7 +388,7 @@ static void pxa_irda_fir_irq_eif(struct pxa_irda *si, struct net_device *dev)
 }
 
 /* FIR interrupt handler */
-static irqreturn_t pxa_irda_fir_irq(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t pxa_irda_fir_irq(int irq, void *dev_id)
 {
 	struct net_device *dev = dev_id;
 	struct pxa_irda *si = netdev_priv(dev);
diff --git a/drivers/net/irda/sa1100_ir.c b/drivers/net/irda/sa1100_ir.c
index 8d5a288d797..937372d0039 100644
--- a/drivers/net/irda/sa1100_ir.c
+++ b/drivers/net/irda/sa1100_ir.c
@@ -579,7 +579,7 @@ static void sa1100_irda_fir_irq(struct net_device *dev)
 	sa1100_irda_rx_dma_start(si);
 }
 
-static irqreturn_t sa1100_irda_irq(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t sa1100_irda_irq(int irq, void *dev_id)
 {
 	struct net_device *dev = dev_id;
 	if (IS_FIR(((struct sa1100_irda *)dev->priv)))
diff --git a/drivers/net/irda/smsc-ircc2.c b/drivers/net/irda/smsc-ircc2.c
index 22358ff68c4..31c623381ea 100644
--- a/drivers/net/irda/smsc-ircc2.c
+++ b/drivers/net/irda/smsc-ircc2.c
@@ -196,7 +196,7 @@ static void smsc_ircc_dma_xmit(struct smsc_ircc_cb *self, int bofs);
 static void smsc_ircc_dma_xmit_complete(struct smsc_ircc_cb *self);
 static void smsc_ircc_change_speed(struct smsc_ircc_cb *self, u32 speed);
 static void smsc_ircc_set_sir_speed(struct smsc_ircc_cb *self, u32 speed);
-static irqreturn_t smsc_ircc_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t smsc_ircc_interrupt(int irq, void *dev_id);
 static irqreturn_t smsc_ircc_interrupt_sir(struct net_device *dev);
 static void smsc_ircc_sir_start(struct smsc_ircc_cb *self);
 #if SMSC_IRCC2_C_SIR_STOP
@@ -1455,7 +1455,7 @@ static void smsc_ircc_sir_receive(struct smsc_ircc_cb *self)
  *    An interrupt from the chip has arrived. Time to do some work
  *
  */
-static irqreturn_t smsc_ircc_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t smsc_ircc_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *) dev_id;
 	struct smsc_ircc_cb *self;
@@ -1520,7 +1520,7 @@ static irqreturn_t smsc_ircc_interrupt(int irq, void *dev_id, struct pt_regs *re
 }
 
 /*
- * Function irport_interrupt_sir (irq, dev_id, regs)
+ * Function irport_interrupt_sir (irq, dev_id)
  *
  *    Interrupt handler for SIR modes
  */
diff --git a/drivers/net/irda/stir4200.c b/drivers/net/irda/stir4200.c
index 12103c93f7e..be8a66e702b 100644
--- a/drivers/net/irda/stir4200.c
+++ b/drivers/net/irda/stir4200.c
@@ -804,7 +804,7 @@ static int stir_transmit_thread(void *arg)
  * Wakes up every ms (usb round trip) with wrapped 
  * data.
  */
-static void stir_rcv_irq(struct urb *urb, struct pt_regs *regs)
+static void stir_rcv_irq(struct urb *urb)
 {
 	struct stir_cb *stir = urb->context;
 	int err;
diff --git a/drivers/net/irda/via-ircc.c b/drivers/net/irda/via-ircc.c
index d916e1257c4..c3ed9b3067e 100644
--- a/drivers/net/irda/via-ircc.c
+++ b/drivers/net/irda/via-ircc.c
@@ -93,8 +93,7 @@ static int via_ircc_hard_xmit_fir(struct sk_buff *skb,
 				  struct net_device *dev);
 static void via_hw_init(struct via_ircc_cb *self);
 static void via_ircc_change_speed(struct via_ircc_cb *self, __u32 baud);
-static irqreturn_t via_ircc_interrupt(int irq, void *dev_id,
-				      struct pt_regs *regs);
+static irqreturn_t via_ircc_interrupt(int irq, void *dev_id);
 static int via_ircc_is_receiving(struct via_ircc_cb *self);
 static int via_ircc_read_dongle_id(int iobase);
 
@@ -1345,13 +1344,12 @@ static int RxTimerHandler(struct via_ircc_cb *self, int iobase)
 
 
 /*
- * Function via_ircc_interrupt (irq, dev_id, regs)
+ * Function via_ircc_interrupt (irq, dev_id)
  *
  *    An interrupt from the chip has arrived. Time to do some work
  *
  */
-static irqreturn_t via_ircc_interrupt(int irq, void *dev_id,
-				      struct pt_regs *regs)
+static irqreturn_t via_ircc_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *) dev_id;
 	struct via_ircc_cb *self;
diff --git a/drivers/net/irda/vlsi_ir.c b/drivers/net/irda/vlsi_ir.c
index 92d646cc9ed..18c68193bf1 100644
--- a/drivers/net/irda/vlsi_ir.c
+++ b/drivers/net/irda/vlsi_ir.c
@@ -1455,8 +1455,7 @@ static int vlsi_ioctl(struct net_device *ndev, struct ifreq *rq, int cmd)
 
 /********************************************************/
 
-static irqreturn_t vlsi_interrupt(int irq, void *dev_instance,
-					struct pt_regs *regs)
+static irqreturn_t vlsi_interrupt(int irq, void *dev_instance)
 {
 	struct net_device *ndev = dev_instance;
 	vlsi_irda_dev_t *idev = ndev->priv;
diff --git a/drivers/net/irda/w83977af_ir.c b/drivers/net/irda/w83977af_ir.c
index 7de1afdeec3..b4fb92a7baa 100644
--- a/drivers/net/irda/w83977af_ir.c
+++ b/drivers/net/irda/w83977af_ir.c
@@ -1111,8 +1111,7 @@ static __u8 w83977af_fir_interrupt(struct w83977af_ir *self, int isr)
  *    An interrupt from the chip has arrived. Time to do some work
  *
  */
-static irqreturn_t w83977af_interrupt(int irq, void *dev_id,
-					struct pt_regs *regs)
+static irqreturn_t w83977af_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *) dev_id;
 	struct w83977af_ir *self;