tick/broadcast: Prevent deep idle if no broadcast device available

Add a check for a installed broadcast device to the oneshot control
function and return busy if not.

[ Split out from a larger combo patch ]

Reported-and-tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos

1 files changed, 7 insertions, 0 deletions

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index ef77b16ad5df..fad3f789beec 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -693,6 +693,13 @@ int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
         ktime_t now;
 
         /*
+         * If there is no broadcast device, tell the caller not to go
+         * into deep idle.
+         */
+        if (!tick_broadcast_device.evtdev)
+                return -EBUSY;
+
+        /*
          * Periodic mode does not care about the enter/exit of power
          * states
          */