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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/pci/hotplug
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/pci/hotplug')
-rw-r--r--drivers/pci/hotplug/cpci_hotplug_core.c2
-rw-r--r--drivers/pci/hotplug/cpqphp.h2
-rw-r--r--drivers/pci/hotplug/cpqphp_ctrl.c2
-rw-r--r--drivers/pci/hotplug/pciehp_hpc.c6
-rw-r--r--drivers/pci/hotplug/shpchp_hpc.c6
5 files changed, 9 insertions, 9 deletions
diff --git a/drivers/pci/hotplug/cpci_hotplug_core.c b/drivers/pci/hotplug/cpci_hotplug_core.c
index d5df5871cfa2..d06ab4045134 100644
--- a/drivers/pci/hotplug/cpci_hotplug_core.c
+++ b/drivers/pci/hotplug/cpci_hotplug_core.c
@@ -342,7 +342,7 @@ cpci_hp_unregister_bus(struct pci_bus *bus)
342 342
343/* This is the interrupt mode interrupt handler */ 343/* This is the interrupt mode interrupt handler */
344static irqreturn_t 344static irqreturn_t
345cpci_hp_intr(int irq, void *data, struct pt_regs *regs) 345cpci_hp_intr(int irq, void *data)
346{ 346{
347 dbg("entered cpci_hp_intr"); 347 dbg("entered cpci_hp_intr");
348 348
diff --git a/drivers/pci/hotplug/cpqphp.h b/drivers/pci/hotplug/cpqphp.h
index c74e9e37e76b..ea040c32f47d 100644
--- a/drivers/pci/hotplug/cpqphp.h
+++ b/drivers/pci/hotplug/cpqphp.h
@@ -409,7 +409,7 @@ extern void cpqhp_remove_debugfs_files (struct controller *ctrl);
409 409
410/* controller functions */ 410/* controller functions */
411extern void cpqhp_pushbutton_thread (unsigned long event_pointer); 411extern void cpqhp_pushbutton_thread (unsigned long event_pointer);
412extern irqreturn_t cpqhp_ctrl_intr (int IRQ, void *data, struct pt_regs *regs); 412extern irqreturn_t cpqhp_ctrl_intr (int IRQ, void *data);
413extern int cpqhp_find_available_resources (struct controller *ctrl, void __iomem *rom_start); 413extern int cpqhp_find_available_resources (struct controller *ctrl, void __iomem *rom_start);
414extern int cpqhp_event_start_thread (void); 414extern int cpqhp_event_start_thread (void);
415extern void cpqhp_event_stop_thread (void); 415extern void cpqhp_event_stop_thread (void);
diff --git a/drivers/pci/hotplug/cpqphp_ctrl.c b/drivers/pci/hotplug/cpqphp_ctrl.c
index ae2dd36efef2..3ec2ad7db49a 100644
--- a/drivers/pci/hotplug/cpqphp_ctrl.c
+++ b/drivers/pci/hotplug/cpqphp_ctrl.c
@@ -889,7 +889,7 @@ int cpqhp_resource_sort_and_combine(struct pci_resource **head)
889} 889}
890 890
891 891
892irqreturn_t cpqhp_ctrl_intr(int IRQ, void *data, struct pt_regs *regs) 892irqreturn_t cpqhp_ctrl_intr(int IRQ, void *data)
893{ 893{
894 struct controller *ctrl = data; 894 struct controller *ctrl = data;
895 u8 schedule_flag = 0; 895 u8 schedule_flag = 0;
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 6ab3b6cd2b54..703a64a39fe8 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -222,7 +222,7 @@ static struct php_ctlr_state_s *php_ctlr_list_head; /* HPC state linked list */
222static int ctlr_seq_num = 0; /* Controller sequence # */ 222static int ctlr_seq_num = 0; /* Controller sequence # */
223static spinlock_t list_lock; 223static spinlock_t list_lock;
224 224
225static irqreturn_t pcie_isr(int IRQ, void *dev_id, struct pt_regs *regs); 225static irqreturn_t pcie_isr(int IRQ, void *dev_id);
226 226
227static void start_int_poll_timer(struct php_ctlr_state_s *php_ctlr, int seconds); 227static void start_int_poll_timer(struct php_ctlr_state_s *php_ctlr, int seconds);
228 228
@@ -239,7 +239,7 @@ static void int_poll_timeout(unsigned long lphp_ctlr)
239 } 239 }
240 240
241 /* Poll for interrupt events. regs == NULL => polling */ 241 /* Poll for interrupt events. regs == NULL => polling */
242 pcie_isr( 0, (void *)php_ctlr, NULL ); 242 pcie_isr( 0, (void *)php_ctlr );
243 243
244 init_timer(&php_ctlr->int_poll_timer); 244 init_timer(&php_ctlr->int_poll_timer);
245 245
@@ -863,7 +863,7 @@ static int hpc_power_off_slot(struct slot * slot)
863 return retval; 863 return retval;
864} 864}
865 865
866static irqreturn_t pcie_isr(int IRQ, void *dev_id, struct pt_regs *regs) 866static irqreturn_t pcie_isr(int IRQ, void *dev_id)
867{ 867{
868 struct controller *ctrl = NULL; 868 struct controller *ctrl = NULL;
869 struct php_ctlr_state_s *php_ctlr; 869 struct php_ctlr_state_s *php_ctlr;
diff --git a/drivers/pci/hotplug/shpchp_hpc.c b/drivers/pci/hotplug/shpchp_hpc.c
index 0f9798df4704..4d8aee119134 100644
--- a/drivers/pci/hotplug/shpchp_hpc.c
+++ b/drivers/pci/hotplug/shpchp_hpc.c
@@ -218,7 +218,7 @@ static spinlock_t list_lock;
218 218
219static atomic_t shpchp_num_controllers = ATOMIC_INIT(0); 219static atomic_t shpchp_num_controllers = ATOMIC_INIT(0);
220 220
221static irqreturn_t shpc_isr(int irq, void *dev_id, struct pt_regs *regs); 221static irqreturn_t shpc_isr(int irq, void *dev_id);
222static void start_int_poll_timer(struct php_ctlr_state_s *php_ctlr, int sec); 222static void start_int_poll_timer(struct php_ctlr_state_s *php_ctlr, int sec);
223static int hpc_check_cmd_status(struct controller *ctrl); 223static int hpc_check_cmd_status(struct controller *ctrl);
224 224
@@ -276,7 +276,7 @@ static void int_poll_timeout(unsigned long lphp_ctlr)
276 DBG_ENTER_ROUTINE 276 DBG_ENTER_ROUTINE
277 277
278 /* Poll for interrupt events. regs == NULL => polling */ 278 /* Poll for interrupt events. regs == NULL => polling */
279 shpc_isr(0, php_ctlr->callback_instance_id, NULL); 279 shpc_isr(0, php_ctlr->callback_instance_id);
280 280
281 init_timer(&php_ctlr->int_poll_timer); 281 init_timer(&php_ctlr->int_poll_timer);
282 if (!shpchp_poll_time) 282 if (!shpchp_poll_time)
@@ -870,7 +870,7 @@ static int hpc_set_bus_speed_mode(struct slot * slot, enum pci_bus_speed value)
870 return retval; 870 return retval;
871} 871}
872 872
873static irqreturn_t shpc_isr(int irq, void *dev_id, struct pt_regs *regs) 873static irqreturn_t shpc_isr(int irq, void *dev_id)
874{ 874{
875 struct controller *ctrl = (struct controller *)dev_id; 875 struct controller *ctrl = (struct controller *)dev_id;
876 struct php_ctlr_state_s *php_ctlr = ctrl->hpc_ctlr_handle; 876 struct php_ctlr_state_s *php_ctlr = ctrl->hpc_ctlr_handle;