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)
The purpose of this patch is to split off the case when a device does
not reply on the lower level (which is reported by HC hardware), and
a case when the device accepted the request, but does not reply at
upper level. This redefinition allows to diagnose issues easier,
without asking the user if the -110 happened "immediately".
The usbmon splits such cases already thanks to its timestamp, but
it's not always available.
I adjusted all drivers which I found affected (by searching for "urb").
Out of tree drivers may suffer a little bit, but I do not expect much
breakage. At worst they may print a few messages.
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Making structs const prevents accidental bugs and with the proper debug
options they're protected against corruption.
Signed-off-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Add device support for a couple more Auerswald TK-devices.
Via Thomas Jackle <dj-tj@gmx.de>, typed in from
http://bugzilla.kernel.org/show_bug.cgi?id=5908.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Remove kmalloc() return value casts that we don't need from
drivers/usb/*
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This lets us remove a lot of code in the drivers that were all checking
the same thing. It also found some bugs in a few of the drivers, which
has been fixed up.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
29 July 2005, Cambridge, MA:
This afternoon Alan Stern submitted a patch to remove the URB_ASYNC_UNLINK
flag from the Linux kernel. Mr. Stern explained, "This flag is a relic
from an earlier, less-well-designed system. For over a year it hasn't
been used for anything other than printing warning messages."
An anonymous spokesman for the Linux kernel development community
commented, "This is exactly the sort of thing we see happening all the
time. As the kernel evolves, support for old techniques and old code can
be jettisoned and replaced by newer, better approaches. Proprietary
operating systems do not have the freedom or flexibility to change so
quickly."
Mr. Stern, a staff member at Harvard University's Rowland Institute who
works on Linux only as a hobby, noted that the patch (labelled as548) did
not update two files, keyspan.c and option.c, in the USB drivers' "serial"
subdirectory. "Those files need more extensive changes," he remarked.
"They examine the status field of several URBs at times when they're not
supposed to. That will need to be fixed before the URB_ASYNC_UNLINK flag
is removed."
Greg Kroah-Hartman, the kernel maintainer responsible for overseeing all
of Linux's USB drivers, did not respond to our inquiries or return our
calls. His only comment was "Applied, thanks."
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Get rid of a bunch of redundant NULL pointer checks in drivers/usb/*,
there's no need to check a pointer for NULL before calling kfree() on it.
Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Index: gregkh-2.6/drivers/usb/class/audio.c
===================================================================
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!
