user/sven/linux.git/fs/timerfd.c, branch v4.9.296

timerfd: Protect the might cancel mechanism proper

2017-05-08T05:47:54Z

commit 1e38da300e1e395a15048b0af1e5305bd91402f6 upstream. The handling of the might_cancel queueing is not properly protected, so parallel operations on the file descriptor can race with each other and lead to list corruptions or use after free. Protect the context for these operations with a seperate lock. The wait queue lock cannot be reused for this because that would create a lock inversion scenario vs. the cancel lock. Replacing might_cancel with an atomic (atomic_t or atomic bit) does not help either because it still can race vs. the actual list operation. Reported-by: Dmitry Vyukov Signed-off-by: Thomas Gleixner Cc: "linux-fsdevel@vger.kernel.org" Cc: syzkaller Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1701311521430.3457@nanos Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

timerfd: Reject ALARM timerfds without CAP_WAKE_ALARM

2016-06-09T21:42:38Z

timerfd gives processes a way to set wake alarms, but unlike timers made using timer_create, timerfds don't check whether the process has CAP_WAKE_ALARM before setting alarm-time timers. CAP_WAKE_ALARM is supposed to gate this behavior and so it makes sense that we should deny permission to create such timerfds if the process doesn't have this capability. Signed-off-by: Eric Caruso Cc: Todd Poynor Link: http://lkml.kernel.org/r/1465427339-96209-1-git-send-email-ejcaruso@chromium.org Signed-off-by: Thomas Gleixner

timerfd: Handle relative timers with CONFIG_TIME_LOW_RES proper

2016-01-17T10:13:55Z

Helge reported that a relative timer can return a remaining time larger than the programmed relative time on parisc and other architectures which have CONFIG_TIME_LOW_RES set. This happens because we add a jiffie to the resulting expiry time to prevent short timeouts. Use the new function hrtimer_expires_remaining_adjusted() to calculate the remaining time. It takes that extra added time into account for relative timers. Reported-and-tested-by: Helge Deller Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra Cc: John Stultz Cc: linux-m68k@lists.linux-m68k.org Cc: dhowells@redhat.com Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20160114164159.354500742@linutronix.de Signed-off-by: Thomas Gleixner

fs: Convert show_fdinfo functions to void

2014-11-05T19:13:23Z

seq_printf functions shouldn't really check the return value. Checking seq_has_overflowed() occasionally is used instead. Update vfs documentation. Link: http://lkml.kernel.org/p/e37e6e7b76acbdcc3bb4ab2a57c8f8ca1ae11b9a.1412031505.git.joe@perches.com Cc: David S. Miller Cc: Al Viro Signed-off-by: Joe Perches [ did a few clean ups ] Signed-off-by: Steven Rostedt

timerfd: Remove an always true check

2014-08-27T09:17:48Z

We would have returned -EINVAL earlier if ticks wasn't set. Signed-off-by: Dan Carpenter Cc: Alexander Viro Cc: Cyrill Gorcunov Link: http://lkml.kernel.org/r/20140801082848.GF28869@mwanda Signed-off-by: Thomas Gleixner

timerfd: Use ktime_mono_to_real()

2014-07-23T17:18:02Z

We have a few other use cases of ktime_get_monotonic_offset() which can be optimized with ktime_mono_to_real(). The timerfd code uses the offset only for comparison, so we can use ktime_mono_to_real(0) for this as well. Funny enough text size shrinks with that on ARM and x8664 !? Signed-off-by: Thomas Gleixner Signed-off-by: John Stultz

timerfd: Implement timerfd_ioctl method to restore timerfd_ctx::ticks, v3

2014-07-18T09:49:57Z

The read() of timerfd files allows to fetch the number of timer ticks while there is no way to set it back from userspace. To restore the timer's state as it was at checkpoint moment we need a path to bring @ticks back. Initially I thought about writing ticks back via write() interface but it seems such API is somehow obscure. Instead implement timerfd_ioctl() method with TFD_IOC_SET_TICKS command which allows to adjust @ticks into non-zero value waking up the waiters. I wrapped code with CONFIG_CHECKPOINT_RESTORE which can be dropped off if there users except c/r camp appear. v2 (by akpm@): - Use define timerfd_ioctl NULL for non c/r config v3: - Use copy_from_user for @ticks fetching since not all arch support get_user for 8 byte argument Signed-off-by: Cyrill Gorcunov Cc: Andrew Morton Cc: Michael Kerrisk Cc: Andrey Vagin Cc: Arnd Bergmann Cc: Christopher Covington Cc: Pavel Emelyanov Cc: Vladimir Davydov Link: http://lkml.kernel.org/r/20140715215703.285617923@openvz.org Signed-off-by: Thomas Gleixner

timerfd: Implement show_fdinfo method

2014-07-18T09:49:57Z

For checkpoint/restore of timerfd files we need to know how exactly the timer were armed, to be able to recreate it on restore stage. Thus implement show_fdinfo method which provides enough information for that. One of significant changes I think is the addition of @settime_flags member. Currently there are two flags TFD_TIMER_ABSTIME and TFD_TIMER_CANCEL_ON_SET, and the second can be found from @might_cancel variable but in case if the flags will be extended in future we most probably will have to somehow remember them explicitly anyway so I guss doing that right now won't hurt. To not bloat the timerfd_ctx structure I've converted @expired to short integer and defined @settime_flags as short too. v2 (by avagin@, vdavydov@ and tglx@): - Add it_value/it_interval fields - Save flags being used in timerfd_setup in context v3 (by tglx@): - don't forget to use CONFIG_PROC_FS v4 (by akpm@): -Use define timerfd_show NULL for non c/r config Signed-off-by: Cyrill Gorcunov Cc: Andrew Morton Cc: Michael Kerrisk Cc: Andrey Vagin Cc: Pavel Emelyanov Cc: Vladimir Davydov Link: http://lkml.kernel.org/r/20140715215703.114365649@openvz.org Signed-off-by: Thomas Gleixner

timerfd: support CLOCK_BOOTTIME clock

2014-01-24T00:57:40Z

Add CLOCK_BOOTTIME support to timerfd Signed-off-by: Greg Hackmann Signed-off-by: John Stultz

timerfd: Add alarm timers

2013-05-29T19:57:34Z

Add support for clocks CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM, thereby enabling wakeup alarm timers via file descriptors. Signed-off-by: Todd Poynor Signed-off-by: John Stultz