linux-toradex.git/kernel/time/alarmtimer.c, branch Colibri_T30_LinuxImageV2.3Beta1_20140804

alarmtimers: Fix time comparison

2011-12-21T20:58:19+00:00

commit c9c024b3f3e07d087974db4c0dc46217fff3a6c0 upstream.

The expiry function compares the timer against current time and does
not expire the timer when the expiry time is >= now. That's wrong. If
the timer is set for now, then it must expire.

Make the condition expiry > now for breaking out the loop.

Signed-off-by: Thomas Gleixner 
Acked-by: John Stultz 
Signed-off-by: Greg Kroah-Hartman

alarmtimers: Avoid possible denial of service with high freq periodic timers

2011-08-10T17:26:09+00:00

Its possible to jam up the alarm timers by setting very small interval
timers, which will cause the alarmtimer subsystem to spend all of its time
firing and restarting timers. This can effectivly lock up a box.

A deeper fix is needed, closely mimicking the hrtimer code, but for now
just cap the interval to 100us to avoid userland hanging the system.

CC: Thomas Gleixner 
CC: stable@kernel.org
Signed-off-by: John Stultz

alarmtimers: Memset itimerspec passed into alarm_timer_get

2011-08-10T14:10:09+00:00

Following common_timer_get, zero out the itimerspec passed in.

CC: Thomas Gleixner 
CC: stable@kernel.org
Signed-off-by: John Stultz

alarmtimers: Avoid possible null pointer traversal

2011-08-10T14:09:53+00:00

We don't check if old_setting is non null before assigning it, so
correct this.

CC: Thomas Gleixner 
CC: stable@kernel.org
Signed-off-by: John Stultz

alarmtimers: Return -ENOTSUPP if no RTC device is present

2011-06-21T23:32:28+00:00

Toralf Förster and Richard Weinberger noted that if there is
no RTC device, the alarm timers core prints out an annoying
"ALARM timers will not wake from suspend" message.

This warning has been removed in a previous patch, however
the issue still remains:  The original idea was to support
alarm timers even if there was no rtc device, as long as the
system didn't go into suspend.

However, after further consideration, communicating to the application
that alarmtimers are not fully functional seems like the better
solution.

So this patch makes it so we return -ENOTSUPP to any posix _ALARM
clockid calls if there is no backing RTC device on the system.

Further this changes the behavior where when there is no rtc device
we will check for one on clock_getres, clock_gettime, timer_create,
and timer_nsleep instead of on suspend.

CC: Toralf Förster 
CC: Richard Weinberger 
CC: Thomas Gleixner 
Reported-by: Toralf Förster 
Reported by: Richard Weinberger 
Signed-off-by: John Stultz

alarmtimers: Handle late rtc module loading

2011-06-21T22:38:33+00:00

The alarmtimers code currently picks a rtc device to use at
late init time. However, if your rtc driver is loaded as a module,
it may be registered after the alarmtimers late init code, leaving
the alarmtimers nonfunctional.

This patch moves the the rtcdevice selection to when we actually try
to use it, allowing us to make use of rtc modules that may have been
loaded at any point since bootup.

CC: Thomas Gleixner 
CC: Meelis Roos 
Reported-by: Meelis Roos 
Signed-off-by: John Stultz

hrtimers: Avoid touching inactive timer bases

2011-05-23T11:59:54+00:00

Instead of iterating over all possible timer bases avoid it by marking
the active bases in the cpu base.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Peter Zijlstra

alarmtimer: Drop device refcount after rtc_open()

2011-05-04T06:18:34+00:00

class_find_device() takes a refcount on the rtc device. rtc_open()
takes another one, so we can drop it after the rtc_open() call.

Signed-off-by: Thomas Gleixner 
Cc: John Stultz

alarmtimer: Check return value of class_find_device()

2011-05-04T06:18:17+00:00

alarmtimer_late_init() uses class_find_device() to find a alarm
capable rtc device. The match callback stores a pointer to the name in
the char pointer handed in from the call site. alarmtimer_late_init()
checks the char pointer for NULL, but the pointer is on the stack and
not initialized to NULL before the call. So it can have random content
when the match function did not identify a device, which leads to
random access in the following rtc_open() call where the pointer is
dereferenced

Instead of relying on the char pointer, check the return value of
class_find_device. If a device is found then the name pointer is valid
as well.

Reported-by: Ingo Molnar 
Cc: John Stultz 
Signed-off-by: Thomas Gleixner

timers: Fix alarmtimer build issues when CONFIG_RTC_CLASS=n

2011-05-02T19:36:57+00:00

Ingo pointed out that the alarmtimers won't build if CONFIG_RTC_CLASS=n.
This patch adds proper ifdefs to the alarmtimer code to disable the rtc
usage if it is not built in.

Reported-by: Ingo Molnar 
Signed-off-by: John Stultz 
Signed-off-by: Thomas Gleixner