BMC/Intel-BMC/linux.git/kernel/time/tick-broadcast.c, branch dev-4.10

tick/broadcast: Prevent deadlock on tick_broadcast_lock

2017-02-13T08:49:31+00:00

tick_broadcast_lock is taken from interrupt context, but the following call chain takes the lock without disabling interrupts: [ 12.703736] _raw_spin_lock+0x3b/0x50 [ 12.703738] tick_broadcast_control+0x5a/0x1a0 [ 12.703742] intel_idle_cpu_online+0x22/0x100 [ 12.703744] cpuhp_invoke_callback+0x245/0x9d0 [ 12.703752] cpuhp_thread_fun+0x52/0x110 [ 12.703754] smpboot_thread_fn+0x276/0x320 So the following deadlock can happen: lock(tick_broadcast_lock); lock(tick_broadcast_lock); intel_idle_cpu_online() is the only place which violates the calling convention of tick_broadcast_control(). This was caused by the removal of the smp function call in course of the cpu hotplug rework. Instead of slapping local_irq_disable/enable() at the call site, we can relax the calling convention and handle it in the core code, which makes the whole machinery more robust. Fixes: 29d7bbada98e ("intel_idle: Remove superfluous SMP fuction call") Reported-by: Gabriel C Signed-off-by: Mike Galbraith Cc: Ruslan Ruslichenko Cc: Jiri Slaby Cc: Greg KH Cc: Borislav Petkov Cc: lwn@lwn.net Cc: Andrew Morton Cc: Linus Torvalds Cc: Anna-Maria Gleixner Cc: Sebastian Siewior Cc: stable Link: http://lkml.kernel.org/r/1486953115.5912.4.camel@gmx.de Signed-off-by: Thomas Gleixner

ktime: Get rid of the union

2016-12-25T16:21:22+00:00

ktime is a union because the initial implementation stored the time in scalar nanoseconds on 64 bit machine and in a endianess optimized timespec variant for 32bit machines. The Y2038 cleanup removed the timespec variant and switched everything to scalar nanoseconds. The union remained, but become completely pointless. Get rid of the union and just keep ktime_t as simple typedef of type s64. The conversion was done with coccinelle and some manual mopping up. Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra

tick/broadcast: Prevent NULL pointer dereference

2016-12-15T11:25:13+00:00

When a disfunctional timer, e.g. dummy timer, is installed, the tick core tries to setup the broadcast timer. If no broadcast device is installed, the kernel crashes with a NULL pointer dereference in tick_broadcast_setup_oneshot() because the function has no sanity check. Reported-by: Mason Signed-off-by: Thomas Gleixner Cc: Mark Rutland Cc: Anna-Maria Gleixner Cc: Richard Cochran Cc: Sebastian Andrzej Siewior Cc: Daniel Lezcano Cc: Peter Zijlstra , Cc: Sebastian Frias Cc: Thibaud Cornic Cc: Robin Murphy Link: http://lkml.kernel.org/r/1147ef90-7877-e4d2-bb2b-5c4fa8d3144b@free.fr

tick: Move the export of tick_broadcast_oneshot_control to the proper place

2015-07-14T10:01:04+00:00

tick_broadcast_oneshot_control got moved from tick-broadcast to tick-common, but the export stayed in the old place. Fix it up. Fixes: f32dd1170511 'tick/broadcast: Make idle check independent from mode and config' Reported-by: Ingo Molnar Signed-off-by: Thomas Gleixner

tick/broadcast: Prevent NULL pointer dereference

2015-07-11T12:26:34+00:00

Dan reported that the recent changes to the broadcast code introduced a potential NULL dereference. Add the proper check. Fixes: e0454311903d "tick/broadcast: Sanity check the shutdown of the local clock_event" Reported-by: Dan Carpenter Signed-off-by: Thomas Gleixner

tick/broadcast: Handle spurious interrupts gracefully

2015-07-07T16:46:48+00:00

Andriy reported that on a virtual machine the warning about negative expiry time in the clock events programming code triggered: hpet: hpet0 irq 40 for MSI hpet: hpet1 irq 41 for MSI Switching to clocksource hpet WARNING: at kernel/time/clockevents.c:239 [] clockevents_program_event+0xdb/0xf0 [] tick_handle_periodic_broadcast+0x41/0x50 [] timer_interrupt+0x15/0x20 When the second hpet is installed as a per cpu timer the broadcast event is not longer required and stopped, which sets the next_evt of the broadcast device to KTIME_MAX. If after that a spurious interrupt happens on the broadcast device, then the current code blindly handles it and tries to reprogram the broadcast device afterwards, which adds the period to next_evt. KTIME_MAX + period results in a negative expiry value causing the WARN_ON in the clockevents code to trigger. Add a proper check for the state of the broadcast device into the interrupt handler and return if the interrupt is spurious. [ Folded in pointer fix from Sudeep ] Reported-by: Andriy Gapon Signed-off-by: Thomas Gleixner Cc: Sudeep Holla Cc: Peter Zijlstra Cc: Preeti U Murthy Link: http://lkml.kernel.org/r/20150705205221.802094647@linutronix.de

tick/broadcast: Check for hrtimer broadcast active early

2015-07-07T16:46:48+00:00

If the current cpu is the one which has the hrtimer based broadcast queued then we better return busy immediately instead of going through loops and hoops to figure that out. [ Split out from a larger combo patch ] Tested-by: Sudeep Holla Signed-off-by: Thomas Gleixner Cc: Suzuki Poulose Cc: Lorenzo Pieralisi Cc: Catalin Marinas Cc: Rafael J. Wysocki Cc: Peter Zijlstra Cc: Preeti U Murthy Cc: Ingo Molnar Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos

tick/broadcast: Return busy when IPI is pending

2015-07-07T16:46:48+00:00

Tell the idle code not to go deep if the broadcast IPI is about to arrive. [ Split out from a larger combo patch ] Tested-by: Sudeep Holla Signed-off-by: Thomas Gleixner Cc: Suzuki Poulose Cc: Lorenzo Pieralisi Cc: Catalin Marinas Cc: Rafael J. Wysocki Cc: Peter Zijlstra Cc: Preeti U Murthy Cc: Ingo Molnar Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos

tick/broadcast: Return busy if periodic mode and hrtimer broadcast

2015-07-07T16:46:48+00:00

If the system is in periodic mode and the broadcast device is hrtimer based, return busy as we have no proper handling for this. [ Split out from a larger combo patch ] Tested-by: Sudeep Holla Signed-off-by: Thomas Gleixner Cc: Suzuki Poulose Cc: Lorenzo Pieralisi Cc: Catalin Marinas Cc: Rafael J. Wysocki Cc: Peter Zijlstra Cc: Preeti U Murthy Cc: Ingo Molnar Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos

tick/broadcast: Move the check for periodic mode inside state handling

2015-07-07T16:46:47+00:00

We need to check more than the periodic mode for proper operation in all runtime combinations. To avoid code duplication move the check into the enter state handling. No functional change. [ Split out from a larger combo patch ] Reported-and-tested-by: Sudeep Holla Signed-off-by: Thomas Gleixner Cc: Suzuki Poulose Cc: Lorenzo Pieralisi Cc: Catalin Marinas Cc: Rafael J. Wysocki Cc: Peter Zijlstra Cc: Preeti U Murthy Cc: Ingo Molnar Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos