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)

20 files changed, 30 insertions, 35 deletions

diff --git a/drivers/net/wireless/airo.c b/drivers/net/wireless/airo.c
index 39d09345027..0a33c8a56e1 100644
--- a/drivers/net/wireless/airo.c
+++ b/drivers/net/wireless/airo.c
@@ -1120,8 +1120,7 @@ static void mpi_receive_802_3(struct airo_info *ai);
 static void mpi_receive_802_11(struct airo_info *ai);
 static int waitbusy (struct airo_info *ai);
 
-static irqreturn_t airo_interrupt( int irq, void* dev_id, struct pt_regs
-			    *regs);
+static irqreturn_t airo_interrupt( int irq, void* dev_id);
 static int airo_thread(void *data);
 static void timer_func( struct net_device *dev );
 static int airo_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
@@ -3151,7 +3150,7 @@ static int airo_thread(void *data) {
 	return 0;
 }
 
-static irqreturn_t airo_interrupt ( int irq, void* dev_id, struct pt_regs *regs) {
+static irqreturn_t airo_interrupt ( int irq, void* dev_id) {
 	struct net_device *dev = (struct net_device *)dev_id;
 	u16 status;
 	u16 fid;
diff --git a/drivers/net/wireless/arlan-main.c b/drivers/net/wireless/arlan-main.c
index bb6bea4f323..4688e56b69c 100644
--- a/drivers/net/wireless/arlan-main.c
+++ b/drivers/net/wireless/arlan-main.c
@@ -78,7 +78,7 @@ static int arlans_found;
 
 static  int 	arlan_open(struct net_device *dev);
 static  int 	arlan_tx(struct sk_buff *skb, struct net_device *dev);
-static  irqreturn_t arlan_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static  irqreturn_t arlan_interrupt(int irq, void *dev_id);
 static  int 	arlan_close(struct net_device *dev);
 static  struct net_device_stats *
 		arlan_statistics		(struct net_device *dev);
@@ -1651,7 +1651,7 @@ end_int_process:
 	return;
 }
 
-static irqreturn_t arlan_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t arlan_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = dev_id;
 	struct arlan_private *priv = netdev_priv(dev);
diff --git a/drivers/net/wireless/atmel.c b/drivers/net/wireless/atmel.c
index 0fc267d626d..31eed85de60 100644
--- a/drivers/net/wireless/atmel.c
+++ b/drivers/net/wireless/atmel.c
@@ -1145,7 +1145,7 @@ next:
 	}
 }
 
-static irqreturn_t service_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t service_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *) dev_id;
 	struct atmel_private *priv = netdev_priv(dev);
diff --git a/drivers/net/wireless/bcm43xx/bcm43xx_main.c b/drivers/net/wireless/bcm43xx/bcm43xx_main.c
index eb65db7393b..bad3452ea89 100644
--- a/drivers/net/wireless/bcm43xx/bcm43xx_main.c
+++ b/drivers/net/wireless/bcm43xx/bcm43xx_main.c
@@ -1834,7 +1834,7 @@ static void bcm43xx_interrupt_ack(struct bcm43xx_private *bcm, u32 reason)
 }
 
 /* Interrupt handler top-half */
-static irqreturn_t bcm43xx_interrupt_handler(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t bcm43xx_interrupt_handler(int irq, void *dev_id)
 {
 	irqreturn_t ret = IRQ_HANDLED;
 	struct bcm43xx_private *bcm = dev_id;
@@ -3963,7 +3963,7 @@ static void bcm43xx_net_poll_controller(struct net_device *net_dev)
 
 	local_irq_save(flags);
 	if (bcm43xx_status(bcm) == BCM43xx_STAT_INITIALIZED)
-		bcm43xx_interrupt_handler(bcm->irq, bcm, NULL);
+		bcm43xx_interrupt_handler(bcm->irq, bcm);
 	local_irq_restore(flags);
 }
 #endif /* CONFIG_NET_POLL_CONTROLLER */
diff --git a/drivers/net/wireless/hostap/hostap_hw.c b/drivers/net/wireless/hostap/hostap_hw.c
index d500012fdc7..ed00ebb6e7f 100644
--- a/drivers/net/wireless/hostap/hostap_hw.c
+++ b/drivers/net/wireless/hostap/hostap_hw.c
@@ -2622,7 +2622,7 @@ static void prism2_check_magic(local_info_t *local)
 
 
 /* Called only from hardware IRQ */
-static irqreturn_t prism2_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t prism2_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *) dev_id;
 	struct hostap_interface *iface;
diff --git a/drivers/net/wireless/ipw2100.c b/drivers/net/wireless/ipw2100.c
index 599e2fe7618..4e4eaa2a99c 100644
--- a/drivers/net/wireless/ipw2100.c
+++ b/drivers/net/wireless/ipw2100.c
@@ -3255,7 +3255,7 @@ static void ipw2100_irq_tasklet(struct ipw2100_priv *priv)
 	IPW_DEBUG_ISR("exit\n");
 }
 
-static irqreturn_t ipw2100_interrupt(int irq, void *data, struct pt_regs *regs)
+static irqreturn_t ipw2100_interrupt(int irq, void *data)
 {
 	struct ipw2100_priv *priv = data;
 	u32 inta, inta_mask;
diff --git a/drivers/net/wireless/ipw2200.c b/drivers/net/wireless/ipw2200.c
index 5685d7ba55b..1f742814a01 100644
--- a/drivers/net/wireless/ipw2200.c
+++ b/drivers/net/wireless/ipw2200.c
@@ -10467,7 +10467,7 @@ static const struct ethtool_ops ipw_ethtool_ops = {
 	.set_eeprom = ipw_ethtool_set_eeprom,
 };
 
-static irqreturn_t ipw_isr(int irq, void *data, struct pt_regs *regs)
+static irqreturn_t ipw_isr(int irq, void *data)
 {
 	struct ipw_priv *priv = data;
 	u32 inta, inta_mask;
diff --git a/drivers/net/wireless/netwave_cs.c b/drivers/net/wireless/netwave_cs.c
index 36b5e004305..6714e0dfa8d 100644
--- a/drivers/net/wireless/netwave_cs.c
+++ b/drivers/net/wireless/netwave_cs.c
@@ -207,7 +207,7 @@ static int netwave_start_xmit( struct sk_buff *skb, struct net_device *dev);
 static int netwave_rx( struct net_device *dev);
 
 /* Interrupt routines */
-static irqreturn_t netwave_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static irqreturn_t netwave_interrupt(int irq, void *dev_id);
 static void netwave_watchdog(struct net_device *);
 
 /* Statistics */
@@ -1072,7 +1072,7 @@ static int netwave_start_xmit(struct sk_buff *skb, struct net_device *dev) {
 } /* netwave_start_xmit */
 
 /*
- * Function netwave_interrupt (irq, dev_id, regs)
+ * Function netwave_interrupt (irq, dev_id)
  *
  *    This function is the interrupt handler for the Netwave card. This
  *    routine will be called whenever: 
@@ -1081,7 +1081,7 @@ static int netwave_start_xmit(struct sk_buff *skb, struct net_device *dev) {
  *	     ready to transmit another packet.
  *	  3. A command has completed execution.
  */
-static irqreturn_t netwave_interrupt(int irq, void* dev_id, struct pt_regs *regs)
+static irqreturn_t netwave_interrupt(int irq, void* dev_id)
 {
     kio_addr_t iobase;
     u_char __iomem *ramBase;
diff --git a/drivers/net/wireless/orinoco.c b/drivers/net/wireless/orinoco.c
index 9e19a963feb..793da5f6934 100644
--- a/drivers/net/wireless/orinoco.c
+++ b/drivers/net/wireless/orinoco.c
@@ -1952,7 +1952,7 @@ static void __orinoco_ev_wterr(struct net_device *dev, hermes_t *hw)
 	       dev->name);
 }
 
-irqreturn_t orinoco_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+irqreturn_t orinoco_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *)dev_id;
 	struct orinoco_private *priv = netdev_priv(dev);
diff --git a/drivers/net/wireless/orinoco.h b/drivers/net/wireless/orinoco.h
index fb5700d6c45..4720fb20d66 100644
--- a/drivers/net/wireless/orinoco.h
+++ b/drivers/net/wireless/orinoco.h
@@ -128,7 +128,7 @@ extern void free_orinocodev(struct net_device *dev);
 extern int __orinoco_up(struct net_device *dev);
 extern int __orinoco_down(struct net_device *dev);
 extern int orinoco_reinit_firmware(struct net_device *dev);
-extern irqreturn_t orinoco_interrupt(int irq, void * dev_id, struct pt_regs *regs);
+extern irqreturn_t orinoco_interrupt(int irq, void * dev_id);
 
 /********************************************************************/
 /* Locking and synchronization functions                            */
diff --git a/drivers/net/wireless/prism54/islpci_dev.c b/drivers/net/wireless/prism54/islpci_dev.c
index ab3c5a27efd..ec1c00f19eb 100644
--- a/drivers/net/wireless/prism54/islpci_dev.c
+++ b/drivers/net/wireless/prism54/islpci_dev.c
@@ -182,7 +182,7 @@ isl_upload_firmware(islpci_private *priv)
 ******************************************************************************/
 
 irqreturn_t
-islpci_interrupt(int irq, void *config, struct pt_regs *regs)
+islpci_interrupt(int irq, void *config)
 {
 	u32 reg;
 	islpci_private *priv = config;
diff --git a/drivers/net/wireless/prism54/islpci_dev.h b/drivers/net/wireless/prism54/islpci_dev.h
index 5049f37455b..2f7e525d0cf 100644
--- a/drivers/net/wireless/prism54/islpci_dev.h
+++ b/drivers/net/wireless/prism54/islpci_dev.h
@@ -198,7 +198,7 @@ islpci_state_t islpci_set_state(islpci_private *priv, islpci_state_t new_state);
 
 #define ISLPCI_TX_TIMEOUT               (2*HZ)
 
-irqreturn_t islpci_interrupt(int, void *, struct pt_regs *);
+irqreturn_t islpci_interrupt(int, void *);
 
 int prism54_post_setup(islpci_private *, int);
 int islpci_reset(islpci_private *, int);
diff --git a/drivers/net/wireless/ray_cs.c b/drivers/net/wireless/ray_cs.c
index e82548ea609..0b381d77015 100644
--- a/drivers/net/wireless/ray_cs.c
+++ b/drivers/net/wireless/ray_cs.c
@@ -130,7 +130,7 @@ static void ray_update_parm(struct net_device *dev, UCHAR objid, UCHAR *value, i
 static void verify_dl_startup(u_long);
 
 /* Prototypes for interrpt time functions **********************************/
-static irqreturn_t ray_interrupt (int reg, void *dev_id, struct pt_regs *regs);
+static irqreturn_t ray_interrupt (int reg, void *dev_id);
 static void clear_interrupt(ray_dev_t *local);
 static void rx_deauthenticate(ray_dev_t *local, struct rcs __iomem *prcs, 
                        unsigned int pkt_addr, int rx_len);
@@ -1940,7 +1940,7 @@ static void set_multicast_list(struct net_device *dev)
 /*=============================================================================
  * All routines below here are run at interrupt time.
 =============================================================================*/
-static irqreturn_t ray_interrupt(int irq, void *dev_id, struct pt_regs * regs)
+static irqreturn_t ray_interrupt(int irq, void *dev_id)
 {
     struct net_device *dev = (struct net_device *)dev_id;
     struct pcmcia_device *link;
diff --git a/drivers/net/wireless/wavelan.c b/drivers/net/wireless/wavelan.c
index 5b69befdab7..24221e476cd 100644
--- a/drivers/net/wireless/wavelan.c
+++ b/drivers/net/wireless/wavelan.c
@@ -3768,7 +3768,7 @@ static int wv_check_ioaddr(unsigned long ioaddr, u8 * mac)
  * This function is the interrupt handler for the WaveLAN card. This
  * routine will be called whenever: 
  */
-static irqreturn_t wavelan_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t wavelan_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev;
 	unsigned long ioaddr;
diff --git a/drivers/net/wireless/wavelan.p.h b/drivers/net/wireless/wavelan.p.h
index 5cb0bc8bb12..72b646c77d5 100644
--- a/drivers/net/wireless/wavelan.p.h
+++ b/drivers/net/wireless/wavelan.p.h
@@ -642,8 +642,7 @@ static int
 /* ---------------------- INTERRUPT HANDLING ---------------------- */
 static irqreturn_t
 	wavelan_interrupt(int,		/* interrupt handler */
-			  void *,
-			  struct pt_regs *);
+			  void *);
 static void
 	wavelan_watchdog(struct net_device *);	/* transmission watchdog */
 /* ------------------- CONFIGURATION CALLBACKS ------------------- */
diff --git a/drivers/net/wireless/wavelan_cs.c b/drivers/net/wireless/wavelan_cs.c
index 0065f057bb1..cadfe132db8 100644
--- a/drivers/net/wireless/wavelan_cs.c
+++ b/drivers/net/wireless/wavelan_cs.c
@@ -4117,8 +4117,7 @@ wv_pcmcia_release(struct pcmcia_device *link)
  */
 static irqreturn_t
 wavelan_interrupt(int		irq,
-		  void *	dev_id,
-		  struct pt_regs * regs)
+		  void *	dev_id)
 {
   struct net_device *	dev;
   net_local *	lp;
diff --git a/drivers/net/wireless/wavelan_cs.p.h b/drivers/net/wireless/wavelan_cs.p.h
index f34a36b0c7b..4d1c4905c74 100644
--- a/drivers/net/wireless/wavelan_cs.p.h
+++ b/drivers/net/wireless/wavelan_cs.p.h
@@ -738,8 +738,7 @@ static void
 /* ---------------------- INTERRUPT HANDLING ---------------------- */
 static irqreturn_t
 	wavelan_interrupt(int,	/* Interrupt handler */
-			  void *,
-			  struct pt_regs *);
+			  void *);
 static void
 	wavelan_watchdog(struct net_device *);	/* Transmission watchdog */
 /* ------------------- CONFIGURATION CALLBACKS ------------------- */
diff --git a/drivers/net/wireless/wl3501_cs.c b/drivers/net/wireless/wl3501_cs.c
index e3ae5f60d5b..a1430352169 100644
--- a/drivers/net/wireless/wl3501_cs.c
+++ b/drivers/net/wireless/wl3501_cs.c
@@ -1145,7 +1145,6 @@ static inline void wl3501_ack_interrupt(struct wl3501_card *this)
  * wl3501_interrupt - Hardware interrupt from card.
  * @irq - Interrupt number
  * @dev_id - net_device
- * @regs - registers
  *
  * We must acknowledge the interrupt as soon as possible, and block the
  * interrupt from the same card immediately to prevent re-entry.
@@ -1154,7 +1153,7 @@ static inline void wl3501_ack_interrupt(struct wl3501_card *this)
  * On the other hand, to prevent SUTRO from malfunctioning, we must
  * unlock the SUTRO as soon as possible.
  */
-static irqreturn_t wl3501_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t wl3501_interrupt(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *)dev_id;
 	struct wl3501_card *this;
diff --git a/drivers/net/wireless/zd1201.c b/drivers/net/wireless/zd1201.c
index 80af9a9fcbb..30057a335a7 100644
--- a/drivers/net/wireless/zd1201.c
+++ b/drivers/net/wireless/zd1201.c
@@ -112,7 +112,7 @@ exit:
 	return err;
 }
 
-static void zd1201_usbfree(struct urb *urb, struct pt_regs *regs)
+static void zd1201_usbfree(struct urb *urb)
 {
 	struct zd1201 *zd = urb->context;
 
@@ -177,7 +177,7 @@ static int zd1201_docmd(struct zd1201 *zd, int cmd, int parm0,
 }
 
 /* Callback after sending out a packet */
-static void zd1201_usbtx(struct urb *urb, struct pt_regs *regs)
+static void zd1201_usbtx(struct urb *urb)
 {
 	struct zd1201 *zd = urb->context;
 	netif_wake_queue(zd->dev);
@@ -185,7 +185,7 @@ static void zd1201_usbtx(struct urb *urb, struct pt_regs *regs)
 }
 
 /* Incoming data */
-static void zd1201_usbrx(struct urb *urb, struct pt_regs *regs)
+static void zd1201_usbrx(struct urb *urb)
 {
 	struct zd1201 *zd = urb->context;
 	int free = 0;
diff --git a/drivers/net/wireless/zd1211rw/zd_usb.c b/drivers/net/wireless/zd1211rw/zd_usb.c
index 5c265ad0485..3faaeb2b7c8 100644
--- a/drivers/net/wireless/zd1211rw/zd_usb.c
+++ b/drivers/net/wireless/zd1211rw/zd_usb.c
@@ -408,7 +408,7 @@ static inline void handle_retry_failed_int(struct urb *urb)
 }
 
 
-static void int_urb_complete(struct urb *urb, struct pt_regs *pt_regs)
+static void int_urb_complete(struct urb *urb)
 {
 	int r;
 	struct usb_int_header *hdr;
@@ -609,7 +609,7 @@ static void handle_rx_packet(struct zd_usb *usb, const u8 *buffer,
 	}
 }
 
-static void rx_urb_complete(struct urb *urb, struct pt_regs *pt_regs)
+static void rx_urb_complete(struct urb *urb)
 {
 	struct zd_usb *usb;
 	struct zd_usb_rx *rx;
@@ -779,7 +779,7 @@ void zd_usb_disable_rx(struct zd_usb *usb)
 	spin_unlock_irqrestore(&rx->lock, flags);
 }
 
-static void tx_urb_complete(struct urb *urb, struct pt_regs *pt_regs)
+static void tx_urb_complete(struct urb *urb)
 {
 	int r;