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authorDavid Howells <dhowells@redhat.com>2006-10-05 09:55:46 -0400
committerDavid Howells <dhowells@warthog.cambridge.redhat.com>2006-10-05 10:10:12 -0400
commit7d12e780e003f93433d49ce78cfedf4b4c52adc5 (patch)
tree6748550400445c11a306b132009f3001e3525df8 /drivers/input/serio/i8042.c
parentda482792a6d1a3fbaaa25fae867b343fb4db3246 (diff)
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)
Diffstat (limited to 'drivers/input/serio/i8042.c')
-rw-r--r--drivers/input/serio/i8042.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 1bb0c76a9259..09b06e605b50 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -108,7 +108,7 @@ static unsigned char i8042_kbd_irq_registered;
108static unsigned char i8042_aux_irq_registered; 108static unsigned char i8042_aux_irq_registered;
109static struct platform_device *i8042_platform_device; 109static struct platform_device *i8042_platform_device;
110 110
111static irqreturn_t i8042_interrupt(int irq, void *dev_id, struct pt_regs *regs); 111static irqreturn_t i8042_interrupt(int irq, void *dev_id);
112 112
113/* 113/*
114 * The i8042_wait_read() and i8042_wait_write functions wait for the i8042 to 114 * The i8042_wait_read() and i8042_wait_write functions wait for the i8042 to
@@ -271,7 +271,7 @@ static int i8042_aux_write(struct serio *serio, unsigned char c)
271 * characters later. 271 * characters later.
272 */ 272 */
273 273
274 i8042_interrupt(0, NULL, NULL); 274 i8042_interrupt(0, NULL);
275 return retval; 275 return retval;
276} 276}
277 277
@@ -309,7 +309,7 @@ static void i8042_stop(struct serio *serio)
309 * to the upper layers. 309 * to the upper layers.
310 */ 310 */
311 311
312static irqreturn_t i8042_interrupt(int irq, void *dev_id, struct pt_regs *regs) 312static irqreturn_t i8042_interrupt(int irq, void *dev_id)
313{ 313{
314 struct i8042_port *port; 314 struct i8042_port *port;
315 unsigned long flags; 315 unsigned long flags;
@@ -379,7 +379,7 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id, struct pt_regs *regs)
379 dfl & SERIO_TIMEOUT ? ", timeout" : ""); 379 dfl & SERIO_TIMEOUT ? ", timeout" : "");
380 380
381 if (likely(port->exists)) 381 if (likely(port->exists))
382 serio_interrupt(port->serio, data, dfl, regs); 382 serio_interrupt(port->serio, data, dfl);
383 383
384 ret = 1; 384 ret = 1;
385 out: 385 out:
@@ -519,7 +519,7 @@ static int __devinit i8042_check_mux(void)
519static struct completion i8042_aux_irq_delivered __devinitdata; 519static struct completion i8042_aux_irq_delivered __devinitdata;
520static int i8042_irq_being_tested __devinitdata; 520static int i8042_irq_being_tested __devinitdata;
521 521
522static irqreturn_t __devinit i8042_aux_test_irq(int irq, void *dev_id, struct pt_regs *regs) 522static irqreturn_t __devinit i8042_aux_test_irq(int irq, void *dev_id)
523{ 523{
524 unsigned long flags; 524 unsigned long flags;
525 unsigned char str, data; 525 unsigned char str, data;
@@ -905,7 +905,7 @@ static int i8042_resume(struct platform_device *dev)
905 if (i8042_ports[I8042_KBD_PORT_NO].serio) 905 if (i8042_ports[I8042_KBD_PORT_NO].serio)
906 i8042_enable_kbd_port(); 906 i8042_enable_kbd_port();
907 907
908 i8042_interrupt(0, NULL, NULL); 908 i8042_interrupt(0, NULL);
909 909
910 return 0; 910 return 0;
911} 911}