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/usb/usbaudio.c | 4 ++-- sound/usb/usbmidi.c | 4 ++-- sound/usb/usbmixer.c | 5 ++--- sound/usb/usx2y/usbusx2y.c | 4 ++-- sound/usb/usx2y/usbusx2yaudio.c | 10 +++++----- sound/usb/usx2y/usx2yhwdeppcm.c | 6 +++--- 6 files changed, 16 insertions(+), 17 deletions(-) (limited to 'sound/usb') diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c index a42acf6d7b6..c82b01c7ad3 100644 --- a/sound/usb/usbaudio.c +++ b/sound/usb/usbaudio.c @@ -653,7 +653,7 @@ static struct snd_urb_ops audio_urb_ops_high_speed[2] = { /* * complete callback from data urb */ -static void snd_complete_urb(struct urb *urb, struct pt_regs *regs) +static void snd_complete_urb(struct urb *urb) { struct snd_urb_ctx *ctx = (struct snd_urb_ctx *)urb->context; struct snd_usb_substream *subs = ctx->subs; @@ -676,7 +676,7 @@ static void snd_complete_urb(struct urb *urb, struct pt_regs *regs) /* * complete callback from sync urb */ -static void snd_complete_sync_urb(struct urb *urb, struct pt_regs *regs) +static void snd_complete_sync_urb(struct urb *urb) { struct snd_urb_ctx *ctx = (struct snd_urb_ctx *)urb->context; struct snd_usb_substream *subs = ctx->subs; diff --git a/sound/usb/usbmidi.c b/sound/usb/usbmidi.c index 0dcf78adb99..b7c5e59b229 100644 --- a/sound/usb/usbmidi.c +++ b/sound/usb/usbmidi.c @@ -223,7 +223,7 @@ static void dump_urb(const char *type, const u8 *data, int length) /* * Processes the data read from the device. */ -static void snd_usbmidi_in_urb_complete(struct urb* urb, struct pt_regs *regs) +static void snd_usbmidi_in_urb_complete(struct urb* urb) { struct snd_usb_midi_in_endpoint* ep = urb->context; @@ -247,7 +247,7 @@ static void snd_usbmidi_in_urb_complete(struct urb* urb, struct pt_regs *regs) snd_usbmidi_submit_urb(urb, GFP_ATOMIC); } -static void snd_usbmidi_out_urb_complete(struct urb* urb, struct pt_regs *regs) +static void snd_usbmidi_out_urb_complete(struct urb* urb) { struct snd_usb_midi_out_endpoint* ep = urb->context; diff --git a/sound/usb/usbmixer.c b/sound/usb/usbmixer.c index e516d6adbb2..1024c178f5c 100644 --- a/sound/usb/usbmixer.c +++ b/sound/usb/usbmixer.c @@ -1710,7 +1710,7 @@ static void snd_usb_mixer_memory_change(struct usb_mixer_interface *mixer, } } -static void snd_usb_mixer_status_complete(struct urb *urb, struct pt_regs *regs) +static void snd_usb_mixer_status_complete(struct urb *urb) { struct usb_mixer_interface *mixer = urb->context; @@ -1772,8 +1772,7 @@ static int snd_usb_mixer_status_create(struct usb_mixer_interface *mixer) return 0; } -static void snd_usb_soundblaster_remote_complete(struct urb *urb, - struct pt_regs *regs) +static void snd_usb_soundblaster_remote_complete(struct urb *urb) { struct usb_mixer_interface *mixer = urb->context; const struct rc_config *rc = mixer->rc_cfg; diff --git a/sound/usb/usx2y/usbusx2y.c b/sound/usb/usx2y/usbusx2y.c index cfec38d7839..e011fcacce9 100644 --- a/sound/usb/usx2y/usbusx2y.c +++ b/sound/usb/usx2y/usbusx2y.c @@ -172,7 +172,7 @@ static void snd_usX2Y_card_private_free(struct snd_card *card); /* * pipe 4 is used for switching the lamps, setting samplerate, volumes .... */ -static void i_usX2Y_Out04Int(struct urb *urb, struct pt_regs *regs) +static void i_usX2Y_Out04Int(struct urb *urb) { #ifdef CONFIG_SND_DEBUG if (urb->status) { @@ -184,7 +184,7 @@ static void i_usX2Y_Out04Int(struct urb *urb, struct pt_regs *regs) #endif } -static void i_usX2Y_In04Int(struct urb *urb, struct pt_regs *regs) +static void i_usX2Y_In04Int(struct urb *urb) { int err = 0; struct usX2Ydev *usX2Y = urb->context; diff --git a/sound/usb/usx2y/usbusx2yaudio.c b/sound/usb/usx2y/usbusx2yaudio.c index f6bd0dee563..e662281a751 100644 --- a/sound/usb/usx2y/usbusx2yaudio.c +++ b/sound/usb/usx2y/usbusx2yaudio.c @@ -306,7 +306,7 @@ static void usX2Y_error_sequence(struct usX2Ydev *usX2Y, usX2Y_clients_stop(usX2Y); } -static void i_usX2Y_urb_complete(struct urb *urb, struct pt_regs *regs) +static void i_usX2Y_urb_complete(struct urb *urb) { struct snd_usX2Y_substream *subs = urb->context; struct usX2Ydev *usX2Y = subs->usX2Y; @@ -350,7 +350,7 @@ static void i_usX2Y_urb_complete(struct urb *urb, struct pt_regs *regs) } static void usX2Y_urbs_set_complete(struct usX2Ydev * usX2Y, - void (*complete)(struct urb *, struct pt_regs *)) + void (*complete)(struct urb *)) { int s, u; for (s = 0; s < 4; s++) { @@ -370,7 +370,7 @@ static void usX2Y_subs_startup_finish(struct usX2Ydev * usX2Y) usX2Y->prepare_subs = NULL; } -static void i_usX2Y_subs_startup(struct urb *urb, struct pt_regs *regs) +static void i_usX2Y_subs_startup(struct urb *urb) { struct snd_usX2Y_substream *subs = urb->context; struct usX2Ydev *usX2Y = subs->usX2Y; @@ -382,7 +382,7 @@ static void i_usX2Y_subs_startup(struct urb *urb, struct pt_regs *regs) wake_up(&usX2Y->prepare_wait_queue); } - i_usX2Y_urb_complete(urb, regs); + i_usX2Y_urb_complete(urb); } static void usX2Y_subs_prepare(struct snd_usX2Y_substream *subs) @@ -663,7 +663,7 @@ static struct s_c2 SetRate48000[] = }; #define NOOF_SETRATE_URBS ARRAY_SIZE(SetRate48000) -static void i_usX2Y_04Int(struct urb *urb, struct pt_regs *regs) +static void i_usX2Y_04Int(struct urb *urb) { struct usX2Ydev *usX2Y = urb->context; diff --git a/sound/usb/usx2y/usx2yhwdeppcm.c b/sound/usb/usx2y/usx2yhwdeppcm.c index 88b72b52590..9acef9d9054 100644 --- a/sound/usb/usx2y/usx2yhwdeppcm.c +++ b/sound/usb/usx2y/usx2yhwdeppcm.c @@ -226,7 +226,7 @@ static inline int usX2Y_usbpcm_usbframe_complete(struct snd_usX2Y_substream *cap } -static void i_usX2Y_usbpcm_urb_complete(struct urb *urb, struct pt_regs *regs) +static void i_usX2Y_usbpcm_urb_complete(struct urb *urb) { struct snd_usX2Y_substream *subs = urb->context; struct usX2Ydev *usX2Y = subs->usX2Y; @@ -294,7 +294,7 @@ static void usX2Y_usbpcm_subs_startup_finish(struct usX2Ydev * usX2Y) usX2Y->prepare_subs = NULL; } -static void i_usX2Y_usbpcm_subs_startup(struct urb *urb, struct pt_regs *regs) +static void i_usX2Y_usbpcm_subs_startup(struct urb *urb) { struct snd_usX2Y_substream *subs = urb->context; struct usX2Ydev *usX2Y = subs->usX2Y; @@ -311,7 +311,7 @@ static void i_usX2Y_usbpcm_subs_startup(struct urb *urb, struct pt_regs *regs) wake_up(&usX2Y->prepare_wait_queue); } - i_usX2Y_usbpcm_urb_complete(urb, regs); + i_usX2Y_usbpcm_urb_complete(urb); } /* -- cgit v1.2.3-70-g09d2