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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/usb/host/ehci-hcd.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/usb/host/ehci-hcd.c')
-rw-r--r--drivers/usb/host/ehci-hcd.c26
1 files changed, 13 insertions, 13 deletions
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 5ac918591131..aac6ec5dd7cf 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -254,8 +254,8 @@ static void ehci_quiesce (struct ehci_hcd *ehci)
254 254
255/*-------------------------------------------------------------------------*/ 255/*-------------------------------------------------------------------------*/
256 256
257static void end_unlink_async (struct ehci_hcd *ehci, struct pt_regs *regs); 257static void end_unlink_async (struct ehci_hcd *ehci);
258static void ehci_work(struct ehci_hcd *ehci, struct pt_regs *regs); 258static void ehci_work(struct ehci_hcd *ehci);
259 259
260#include "ehci-hub.c" 260#include "ehci-hub.c"
261#include "ehci-mem.c" 261#include "ehci-mem.c"
@@ -280,7 +280,7 @@ static void ehci_iaa_watchdog (unsigned long param)
280 ehci_vdbg (ehci, "lost IAA\n"); 280 ehci_vdbg (ehci, "lost IAA\n");
281 COUNT (ehci->stats.lost_iaa); 281 COUNT (ehci->stats.lost_iaa);
282 writel (STS_IAA, &ehci->regs->status); 282 writel (STS_IAA, &ehci->regs->status);
283 end_unlink_async (ehci, NULL); 283 end_unlink_async (ehci);
284 } 284 }
285 } 285 }
286 286
@@ -299,7 +299,7 @@ static void ehci_watchdog (unsigned long param)
299 start_unlink_async (ehci, ehci->async); 299 start_unlink_async (ehci, ehci->async);
300 300
301 /* ehci could run by timer, without IRQs ... */ 301 /* ehci could run by timer, without IRQs ... */
302 ehci_work (ehci, NULL); 302 ehci_work (ehci);
303 303
304 spin_unlock_irqrestore (&ehci->lock, flags); 304 spin_unlock_irqrestore (&ehci->lock, flags);
305} 305}
@@ -342,7 +342,7 @@ static void ehci_port_power (struct ehci_hcd *ehci, int is_on)
342 * ehci_work is called from some interrupts, timers, and so on. 342 * ehci_work is called from some interrupts, timers, and so on.
343 * it calls driver completion functions, after dropping ehci->lock. 343 * it calls driver completion functions, after dropping ehci->lock.
344 */ 344 */
345static void ehci_work (struct ehci_hcd *ehci, struct pt_regs *regs) 345static void ehci_work (struct ehci_hcd *ehci)
346{ 346{
347 timer_action_done (ehci, TIMER_IO_WATCHDOG); 347 timer_action_done (ehci, TIMER_IO_WATCHDOG);
348 348
@@ -353,9 +353,9 @@ static void ehci_work (struct ehci_hcd *ehci, struct pt_regs *regs)
353 if (ehci->scanning) 353 if (ehci->scanning)
354 return; 354 return;
355 ehci->scanning = 1; 355 ehci->scanning = 1;
356 scan_async (ehci, regs); 356 scan_async (ehci);
357 if (ehci->next_uframe != -1) 357 if (ehci->next_uframe != -1)
358 scan_periodic (ehci, regs); 358 scan_periodic (ehci);
359 ehci->scanning = 0; 359 ehci->scanning = 0;
360 360
361 /* the IO watchdog guards against hardware or driver bugs that 361 /* the IO watchdog guards against hardware or driver bugs that
@@ -397,7 +397,7 @@ static void ehci_stop (struct usb_hcd *hcd)
397 /* root hub is shut down separately (first, when possible) */ 397 /* root hub is shut down separately (first, when possible) */
398 spin_lock_irq (&ehci->lock); 398 spin_lock_irq (&ehci->lock);
399 if (ehci->async) 399 if (ehci->async)
400 ehci_work (ehci, NULL); 400 ehci_work (ehci);
401 spin_unlock_irq (&ehci->lock); 401 spin_unlock_irq (&ehci->lock);
402 ehci_mem_cleanup (ehci); 402 ehci_mem_cleanup (ehci);
403 403
@@ -573,7 +573,7 @@ static int ehci_run (struct usb_hcd *hcd)
573 573
574/*-------------------------------------------------------------------------*/ 574/*-------------------------------------------------------------------------*/
575 575
576static irqreturn_t ehci_irq (struct usb_hcd *hcd, struct pt_regs *regs) 576static irqreturn_t ehci_irq (struct usb_hcd *hcd)
577{ 577{
578 struct ehci_hcd *ehci = hcd_to_ehci (hcd); 578 struct ehci_hcd *ehci = hcd_to_ehci (hcd);
579 u32 status; 579 u32 status;
@@ -619,7 +619,7 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd, struct pt_regs *regs)
619 /* complete the unlinking of some qh [4.15.2.3] */ 619 /* complete the unlinking of some qh [4.15.2.3] */
620 if (status & STS_IAA) { 620 if (status & STS_IAA) {
621 COUNT (ehci->stats.reclaim); 621 COUNT (ehci->stats.reclaim);
622 end_unlink_async (ehci, regs); 622 end_unlink_async (ehci);
623 bh = 1; 623 bh = 1;
624 } 624 }
625 625
@@ -670,7 +670,7 @@ dead:
670 } 670 }
671 671
672 if (bh) 672 if (bh)
673 ehci_work (ehci, regs); 673 ehci_work (ehci);
674 spin_unlock (&ehci->lock); 674 spin_unlock (&ehci->lock);
675 return IRQ_HANDLED; 675 return IRQ_HANDLED;
676} 676}
@@ -727,7 +727,7 @@ static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
727 727
728 /* failfast */ 728 /* failfast */
729 if (!HC_IS_RUNNING (ehci_to_hcd(ehci)->state)) 729 if (!HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
730 end_unlink_async (ehci, NULL); 730 end_unlink_async (ehci);
731 731
732 /* defer till later if busy */ 732 /* defer till later if busy */
733 else if (ehci->reclaim) { 733 else if (ehci->reclaim) {
@@ -787,7 +787,7 @@ static int ehci_urb_dequeue (struct usb_hcd *hcd, struct urb *urb)
787 intr_deschedule (ehci, qh); 787 intr_deschedule (ehci, qh);
788 /* FALL THROUGH */ 788 /* FALL THROUGH */
789 case QH_STATE_IDLE: 789 case QH_STATE_IDLE:
790 qh_completions (ehci, qh, NULL); 790 qh_completions (ehci, qh);
791 break; 791 break;
792 default: 792 default:
793 ehci_dbg (ehci, "bogus qh %p state %d\n", 793 ehci_dbg (ehci, "bogus qh %p state %d\n",