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Commit 74a03b69 authored by John Stultz's avatar John Stultz Committed by Thomas Gleixner
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clockevents: prevent endless loop in tick_handle_periodic()



tick_handle_periodic() can lock up hard when a one shot clock event
device is used in combination with jiffies clocksource.

Avoid an endless loop issue by requiring that a highres valid
clocksource be installed before we call tick_periodic() in a loop when
using ONESHOT mode. The result is we will only increment jiffies once
per interrupt until a continuous hardware clocksource is available.

Without this, we can run into a endless loop, where each cycle through
the loop, jiffies is updated which increments time by tick_period or
more (due to clock steering), which can cause the event programming to
think the next event was before the newly incremented time and fail
causing tick_periodic() to be called again and the whole process loops
forever.

[ Impact: prevent hard lock up ]

Signed-off-by: default avatarJohn Stultz <johnstul@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org
parent 091438dd
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