net_sched: Add flow control support to prio qdisc

Add enable_flow flag to the prio qdisc.  Packet flow is
enabled by default, but can be disabled from userspace
(e.g. IPROUTE2 tc tool).  This allows for suspending packet
dequeue on a per-qdisc basis, which is needed to supprot
Quality of Service (QOS) when using WWAN modem.

Change-Id: I932f296be946f1acc3b00c7d8569bbb733d33622
Acked-by: Andrew Richardson <randrew@qualcomm.com>
CRs-Fixed: 283471
Signed-off-by: Tianyi Gou <tgou@codeaurora.org>
ARM: 7809/1: perf: fix event validation for software group leaders

It is possible to construct an event group with a software event as a
group leader and then subsequently add a hardware event to the group.
This results in the event group being validated by adding all members
of the group to a fake PMU and attempting to allocate each event on
their respective PMU.

Unfortunately, for software events wthout a corresponding arm_pmu, this
results in a kernel crash attempting to dereference the ->get_event_idx
function pointer.

This patch fixes the problem by checking explicitly for software events
and ignoring those in event validation (since they can always be
scheduled). We will probably want to revisit this for 3.12, since the
validation checks don't appear to work correctly when dealing with
multiple hardware PMUs anyway.

Cc: <stable@vger.kernel.org>
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Conflicts:

	arch/arm/kernel/perf_event.c