Commit Graph

10 Commits

Author SHA1 Message Date
David Howells
7d12e780e0 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)
2006-10-05 15:10:12 +01:00
Samuel Tardieu
795b89d207 [WATCHDOG] use ENOTTY instead of ENOIOCTLCMD in ioctl()
Return ENOTTY instead of ENOIOCTLCMD in user-visible ioctl() results

The watchdog drivers used to return ENOIOCTLCMD for bad ioctl() commands.
ENOIOCTLCMD should not be visible by the user, so use ENOTTY instead.

Signed-off-by: Samuel Tardieu <sam@rfc1149.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
2006-10-02 23:08:34 +02:00
Arjan van de Ven
62322d2554 [PATCH] make more file_operation structs static
Mark the static struct file_operations in drivers/char as const.  Making
them const prevents accidental bugs, and moves them to the .rodata section
so that they no longer do any false sharing; in addition with the proper
debug option they are then protected against corruption..

[akpm@osdl.org: build fix]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-03 15:26:59 -07:00
Jörn Engel
6ab3d5624e Remove obsolete #include <linux/config.h>
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-06-30 19:25:36 +02:00
Wim Van Sebroeck
58b519f3e5 [WATCHDOG] add WDIOC_GETTIMELEFT ioctl
Some watchdog drivers have the ability to report the remaining time
before the system will reboot. With the WDIOC_GETTIMELEFT ioctl
you can now read the time left before the watchdog would reboot
your system.

The following drivers support this new IOCTL:
i8xx_tco.c, pcwd_pci.c and pcwd_usb.c .

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@osdl.org>
2006-06-20 19:00:30 +02:00
Adrian Bunk
c9d1a0b8d5 [WATCHDOG] pcwd_usb.c: fix a NULL pointer dereference
The Coverity checker noted that this resulted in a NULL pointer
reference if we were coming from

        if (usb_pcwd == NULL) {
                printk(KERN_ERR PFX "Out of memory\n");
                    goto error;
        }

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@osdl.org>
2006-04-02 18:51:50 +02:00
Ingo Molnar
6f87f0deeb [PATCH] sem2mutex: drivers/char/
Semaphore to mutex conversion.

The conversion was generated via scripts, and the result was validated
automatically via a script as well.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-23 07:38:11 -08:00
Greg Kroah-Hartman
75318d2d7c [PATCH] USB: remove .owner field from struct usb_driver
It is no longer needed, so let's remove it, saving a bit of memory.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-01-04 13:48:34 -08:00
Andrey Panin
4bfdf37830 [PATCH] consolidate CONFIG_WATCHDOG_NOWAYOUT handling
Attached patch removes #ifdef CONFIG_WATCHDOG_NOWAYOUT mess duplicated in
almost every watchdog driver and replaces it with common define in
linux/watchdog.h.

Signed-off-by: Andrey Panin <pazke@donpac.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-27 16:25:54 -07:00
Linus Torvalds
1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00