linux-toradex.git/kernel/posix-timers.c, branch v2.6.22.13

posix-timers: Prevent softirq starvation by small intervals and SIG_IGN

2007-06-21T22:57:04+00:00

posix-timers which deliver an ignored signal are currently rearmed in
the timer softirq: This is necessary because the timer needs to be
delivered again when SIG_IGN is removed. This is not a problem, when
the interval is reasonable.

With high resolution timers enabled one might arm a posix timer with a
very small interval and ignore the signal. This might lead to a
softirq starvation when the interval is so small that the timer is
requeued onto the softirq pending list right away.

This problem was pointed out by Jan Kiszka. Thanks Jan !

The correct solution would be to stop the timer, when the signal is
ignored and rearm it when SIG_IGN is removed. Unfortunately this
requires modification in sigaction and involves non trivial sighand
locking. It's too late in the release cycle for such a change.

For now we just keep the timer running and enforce that the timer only
fires every jiffie. This does not break anything as we keep the
overrun counter correct. It adds a little inaccuracy to the
timer_gettime() interface, but...

The more complex change is necessary anyway to fix another short
coming of the current implementation, which I discovered while looking
at this problem: A pending signal is discarded when SIG_IGN is set. In
case that a posixtimer signal is pending then it is discarded as well,
but when SIG_IGN is removed later nothing rearms the timer. This is
not new, it's that way since posix timers have been merged. So nothing
to worry about right now.

I have a working solution to fix all of this, but the impact is too
large for both stable and 2.6.22. I'm going to send it out for review
in the next days.

This should go into 2.6.21.stable as well.

Signed-off-by: Thomas Gleixner 
Acked-by: Ingo Molnar 
Cc: Jan Kiszka 
Cc: Ulrich Drepper 
Cc: Stable Team 
Signed-off-by: Linus Torvalds

header cleaning: don't include smp_lock.h when not used

2007-05-08T18:15:07+00:00

Remove includes of  where it is not used/needed.
Suggested by Al Viro.

Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).

Signed-off-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] hrtimers: add high resolution timer support

2007-02-16T16:13:59+00:00

Implement high resolution timers on top of the hrtimers infrastructure and the
clockevents / tick-management framework.  This provides accurate timers for
all hrtimer subsystem users.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Cc: john stultz 
Cc: Roman Zippel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] hrtimers: namespace and enum cleanup

2007-02-16T16:13:58+00:00

- hrtimers did not use the hrtimer_restart enum and relied on the implict
  int representation. Fix the prototypes and the functions using the enums.
- Use seperate name spaces for the enumerations
- Convert hrtimer_restart macro to inline function
- Add comments

No functional changes.

[akpm@osdl.org: fix input driver]
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Cc: john stultz 
Cc: Roman Zippel 
Cc: Dmitry Torokhov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc().

2007-02-11T18:51:27+00:00

Replace appropriate pairs of "kmem_cache_alloc()" + "memset(0)" with the
corresponding "kmem_cache_zalloc()" call.

Signed-off-by: Robert P. J. Day 
Cc: "Luck, Tony" 
Cc: Andi Kleen 
Cc: Roland McGrath 
Cc: James Bottomley 
Cc: Greg KH 
Acked-by: Joel Becker 
Cc: Steven Whitehouse 
Cc: Jan Kara 
Cc: Michael Halcrow 
Cc: "David S. Miller" 
Cc: Stephen Smalley 
Cc: James Morris 
Cc: Chris Wright 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] slab: remove kmem_cache_t

2006-12-07T16:39:25+00:00

Replace all uses of kmem_cache_t with struct kmem_cache.

The patch was generated using the following script:

	#!/bin/sh
	#
	# Replace one string by another in all the kernel sources.
	#

	set -e

	for file in `find * -name "*.c" -o -name "*.h"|xargs grep -l $1`; do
		quilt add $file
		sed -e "1,\$s/$1/$2/g" $file >/tmp/$$
		mv /tmp/$$ $file
		quilt refresh
	done

The script was run like this

	sh replace kmem_cache_t "struct kmem_cache"

Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fix file specification in comments

2006-10-03T21:01:26+00:00

Many files include the filename at the beginning, serveral used a wrong one.

Signed-off-by: Uwe Zeisberger 
Signed-off-by: Adrian Bunk

[PATCH] posix-timers: Fix clock_nanosleep() doesn't return the remaining time in compatibility mode

2006-09-29T16:18:15+00:00

The clock_nanosleep() function does not return the time remaining when the
sleep is interrupted by a signal.

This patch creates a new call out, compat_clock_nanosleep_restart(), which
handles returning the remaining time after a sleep is interrupted.  This
patch revives clock_nanosleep_restart().  It is now accessed via the new
call out.  The compat_clock_nanosleep_restart() is used for compatibility
access.

Since this is implemented in compatibility mode the normal path is
virtually unaffected - no real performance impact.

Signed-off-by: Toyo Abe 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] hrtimers: remove data field

2006-03-26T16:57:03+00:00

The nanosleep cleanup allows to remove the data field of hrtimer.  The
callback function can use container_of() to get it's own data.  Since the
hrtimer structure is anyway embedded in other structures, this adds no
overhead.

Signed-off-by: Roman Zippel 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] hrtimers: posix-timer: cleanup common_timer_get()

2006-03-26T16:57:02+00:00

Cleanup common_timer_get() a little.

Signed-off-by: Roman Zippel 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds