From 7d12e780e003f93433d49ce78cfedf4b4c52adc5 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 5 Oct 2006 14:55:46 +0100 Subject: 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 (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit) --- sound/aoa/soundbus/i2sbus/i2sbus-core.c | 5 ++--- sound/aoa/soundbus/i2sbus/i2sbus-pcm.c | 4 ++-- sound/aoa/soundbus/i2sbus/i2sbus.h | 4 ++-- 3 files changed, 6 insertions(+), 7 deletions(-) (limited to 'sound/aoa/soundbus/i2sbus') diff --git a/sound/aoa/soundbus/i2sbus/i2sbus-core.c b/sound/aoa/soundbus/i2sbus/i2sbus-core.c index 23190aa6bc7b..e593a1333fe3 100644 --- a/sound/aoa/soundbus/i2sbus/i2sbus-core.c +++ b/sound/aoa/soundbus/i2sbus/i2sbus-core.c @@ -93,7 +93,7 @@ static void i2sbus_release_dev(struct device *dev) kfree(i2sdev); } -static irqreturn_t i2sbus_bus_intr(int irq, void *devid, struct pt_regs *regs) +static irqreturn_t i2sbus_bus_intr(int irq, void *devid) { struct i2sbus_dev *dev = devid; u32 intreg; @@ -165,8 +165,7 @@ static int i2sbus_add_dev(struct macio_dev *macio, static const char *rnames[] = { "i2sbus: %s (control)", "i2sbus: %s (tx)", "i2sbus: %s (rx)" }; - static irqreturn_t (*ints[])(int irq, void *devid, - struct pt_regs *regs) = { + static irq_handler_t ints[] = { i2sbus_bus_intr, i2sbus_tx_intr, i2sbus_rx_intr diff --git a/sound/aoa/soundbus/i2sbus/i2sbus-pcm.c b/sound/aoa/soundbus/i2sbus/i2sbus-pcm.c index 3049015a04f1..5eff30b10201 100644 --- a/sound/aoa/soundbus/i2sbus/i2sbus-pcm.c +++ b/sound/aoa/soundbus/i2sbus/i2sbus-pcm.c @@ -642,13 +642,13 @@ static inline void handle_interrupt(struct i2sbus_dev *i2sdev, int in) spin_unlock(&i2sdev->low_lock); } -irqreturn_t i2sbus_tx_intr(int irq, void *devid, struct pt_regs *regs) +irqreturn_t i2sbus_tx_intr(int irq, void *devid) { handle_interrupt((struct i2sbus_dev *)devid, 0); return IRQ_HANDLED; } -irqreturn_t i2sbus_rx_intr(int irq, void *devid, struct pt_regs * regs) +irqreturn_t i2sbus_rx_intr(int irq, void *devid) { handle_interrupt((struct i2sbus_dev *)devid, 1); return IRQ_HANDLED; diff --git a/sound/aoa/soundbus/i2sbus/i2sbus.h b/sound/aoa/soundbus/i2sbus/i2sbus.h index 0c69d209be50..ec20ee615d7f 100644 --- a/sound/aoa/soundbus/i2sbus/i2sbus.h +++ b/sound/aoa/soundbus/i2sbus/i2sbus.h @@ -97,9 +97,9 @@ i2sbus_attach_codec(struct soundbus_dev *dev, struct snd_card *card, extern void i2sbus_detach_codec(struct soundbus_dev *dev, void *data); extern irqreturn_t -i2sbus_tx_intr(int irq, void *devid, struct pt_regs *regs); +i2sbus_tx_intr(int irq, void *devid); extern irqreturn_t -i2sbus_rx_intr(int irq, void *devid, struct pt_regs *regs); +i2sbus_rx_intr(int irq, void *devid); /* control specific functions */ extern int i2sbus_control_init(struct macio_dev* dev, -- cgit v1.2.3