kernel/linux.git/arch/um/os-Linux/time.c, branch v6.18.21

um: Remove unused timeval_to_ns() function

2022-03-11T09:49:50+00:00

The timeval_to_ns() function doesn't appear to be used anywhere, as far as I (or git grep) can tell, and clang throws up a warning about it: ../arch/um/os-Linux/time.c:21:25: warning: unused function 'timeval_to_ns' [-Wunused-function] static inline long long timeval_to_ns(const struct timeval *tv) ^ 1 warning generated. Signed-off-by: David Gow Acked-By: Anton Ivanov Signed-off-by: Richard Weinberger

um: fix os_idle_sleep() to not hang

2021-01-26T21:11:38+00:00

Changing os_idle_sleep() to use pause() (I accidentally described it as an empty select() in the commit log because I had changed it from that to pause() in a later revision) exposed a race condition in the idle code. The following can happen: timer_settime(0, 0, {it_interval={tv_sec=0, tv_nsec=0}, it_value={tv_sec=0, tv_nsec=624017}}, NULL) = 0 ... pause() and we now hang forever. This was previously possible as well, but it could never cause UML to hang for more than a second since we could only sleep for that much, so at most you'd notice a "hiccup" in the UML. Obviously, any sort of external interrupt also "saves" it and interrupts pause(). Fix this by properly handling the race, rather than papering over it again: - first, block SIGALRM, and obtain the old signal set - check the timer - suspend, waiting for any signal out of the old set, if, and only if, the timer will fire in the future - restore the old signal mask This ensures race-free operation: as it's blocked, the signal won't be delivered while we're looking at the timer even if it were to be triggered right _after_ we've returned from timer_gettime() with a non-zero value (telling us the timer will trigger). Thus, despite getting to sigsuspend() because timer_gettime() told us we're still waiting, we'll not hang because sigsuspend() will return immediately due to the pending signal. Fixes: 49da38a3ef33 ("um: Simplify os_idle_sleep() and sleep longer") Signed-off-by: Johannes Berg Acked-By: Anton Ivanov Signed-off-by: Richard Weinberger

um: Simplify os_idle_sleep() and sleep longer

2020-12-13T21:22:37+00:00

There really is no reason to pass the amount of time we should sleep, especially since it's just hard-coded to one second. Additionally, one second isn't really all that long, and as we are expecting to be woken up by a signal, we can sleep longer and avoid doing some work every second, so replace the current clock_nanosleep() with just an empty select() that can _only_ be woken up by a signal. We can also remove the deliver_alarm() since we don't need to do that when we got e.g. SIGIO that woke us up, and if we got SIGALRM the signal handler will actually (have) run, so it's just unnecessary extra work. Similarly, in time-travel mode, just program the wakeup event from idle to be S64_MAX, which is basically the most you could ever simulate to. Of course, you should already have an event in the list that's earlier and will cause a wakeup, normally that's the regular timer interrupt, though in suspend it may (later) also be an RTC event. Since actually getting to this point would be a bug and you can't ever get out again, panic() on it in the time control code. Signed-off-by: Johannes Berg Acked-By: Anton Ivanov Signed-off-by: Richard Weinberger

um: Move timer-internal.h to non-shared

2020-03-29T21:28:43+00:00

This file isn't really shared, it's only used on the kernel side, not on the user side. Remove the include from the user-side and move the file to a better place. While at it, rename it to time-internal.h, it's not really just timers but all kinds of things related to timekeeping. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

um: Add SPDX headers for files in arch/um/os-Linux

2019-09-15T19:37:17+00:00

Convert files to use SPDX header. All files are licensed under the GPLv2. Signed-off-by: Alex Dewar Signed-off-by: Richard Weinberger

um: Pass nsecs to os timer functions

2019-07-02T21:27:29+00:00

This makes the code clearer and lets the time travel patch have the actual time used for these functions in just one place. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

um: Timer code cleanup

2019-07-02T21:27:00+00:00

There are some unused functions, and some others that have unused arguments; clean up the timer code a bit. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

um: fix os_timer_one_shot()

2019-07-02T21:26:57+00:00

os_timer_one_shot() gets passed a value "unsigned long delta", so must not have an "int ticks" as that actually ends up being -1, and thus triggering a timer over and over again. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

um: Switch clocksource to hrtimers

2015-11-06T21:54:49+00:00

UML is using an obsolete itimer call for all timers and "polls" for kernel space timer firing in its userspace portion resulting in a long list of bugs and incorrect behaviour(s). It also uses ITIMER_VIRTUAL for its timer which results in the timer being dependent on it running and the cpu load. This patch fixes this by moving to posix high resolution timers firing off CLOCK_MONOTONIC and relaying the timer correctly to the UML userspace. Fixes: - crashes when hosts suspends/resumes - broken userspace timers - effecive ~40Hz instead of what they should be. Note - this modifies skas behavior by no longer setting an itimer per clone(). Timer events are relayed instead. - kernel network packet scheduling disciplines - tcp behaviour especially under load - various timer related corner cases Finally, overall responsiveness of userspace is better. Signed-off-by: Thomas Meyer Signed-off-by: Anton Ivanov [rw: massaged commit message] Signed-off-by: Richard Weinberger

nohz: Rename CONFIG_NO_HZ to CONFIG_NO_HZ_COMMON

2013-04-03T11:56:03+00:00

We are planning to convert the dynticks Kconfig options layout into a choice menu. The user must be able to easily pick any of the following implementations: constant periodic tick, idle dynticks, full dynticks. As this implies a mutual exclusion, the two dynticks implementions need to converge on the selection of a common Kconfig option in order to ease the sharing of a common infrastructure. It would thus seem pretty natural to reuse CONFIG_NO_HZ to that end. It already implements all the idle dynticks code and the full dynticks depends on all that code for now. So ideally the choice menu would propose CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED then both would select CONFIG_NO_HZ. On the other hand we want to stay backward compatible: if CONFIG_NO_HZ is set in an older config file, we want to enable CONFIG_NO_HZ_IDLE by default. But we can't afford both at the same time or we run into a circular dependency: 1) CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED both select CONFIG_NO_HZ 2) If CONFIG_NO_HZ is set, we default to CONFIG_NO_HZ_IDLE We might be able to support that from Kconfig/Kbuild but it may not be wise to introduce such a confusing behaviour. So to solve this, create a new CONFIG_NO_HZ_COMMON option which gathers the common code between idle and full dynticks (that common code for now is simply the idle dynticks code) and select it from their referring Kconfig. Then we'll later create CONFIG_NO_HZ_IDLE and map CONFIG_NO_HZ to it for backward compatibility. Signed-off-by: Frederic Weisbecker Cc: Andrew Morton Cc: Chris Metcalf Cc: Christoph Lameter Cc: Geoff Levand Cc: Gilad Ben Yossef Cc: Hakan Akkan Cc: Ingo Molnar Cc: Kevin Hilman Cc: Li Zhong Cc: Namhyung Kim Cc: Paul E. McKenney Cc: Paul Gortmaker Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner