Revision bb143f814ea488769ca2e79e0b376139cb5f134b authored by Vineet Gupta on 23 February 2016, 06:25:16 UTC, committed by Vineet Gupta on 24 February 2016, 05:37:28 UTC
ARConnect/MCIP Inter-Core-Interrupt module can't send interrupt to local core. So use core intc capability to trigger software interrupt to self, using an unsued IRQ #21. This showed up as csd deadlock with LTP trace_sched on a dual core system. This test acts as scheduler fuzzer, triggering all sorts of schedulting activity. Trouble starts with IPI to self, which doesn't get delivered (effectively lost due to H/w capability), but the msg intended to be sent remain enqueued in per-cpu @ipi_data. All subsequent IPIs to this core from other cores get elided due to the IPI coalescing optimization in ipi_send_msg_one() where a pending msg implies an IPI already sent and assumes other core is yet to ack it. After the elided IPI, other core simply goes into csd_lock_wait() but never comes out as this core never sees the interrupt. Fixes STAR 9001008624 Cc: Peter Zijlstra <peterz@infradead.org> Cc: <stable@vger.kernel.org> [4.2] Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
1 parent 3e5177c
netevent.c
/*
* Network event notifiers
*
* Authors:
* Tom Tucker <tom@opengridcomputing.com>
* Steve Wise <swise@opengridcomputing.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Fixes:
*/
#include <linux/rtnetlink.h>
#include <linux/notifier.h>
#include <linux/export.h>
#include <net/netevent.h>
static ATOMIC_NOTIFIER_HEAD(netevent_notif_chain);
/**
* register_netevent_notifier - register a netevent notifier block
* @nb: notifier
*
* Register a notifier to be called when a netevent occurs.
* The notifier passed is linked into the kernel structures and must
* not be reused until it has been unregistered. A negative errno code
* is returned on a failure.
*/
int register_netevent_notifier(struct notifier_block *nb)
{
return atomic_notifier_chain_register(&netevent_notif_chain, nb);
}
EXPORT_SYMBOL_GPL(register_netevent_notifier);
/**
* netevent_unregister_notifier - unregister a netevent notifier block
* @nb: notifier
*
* Unregister a notifier previously registered by
* register_neigh_notifier(). The notifier is unlinked into the
* kernel structures and may then be reused. A negative errno code
* is returned on a failure.
*/
int unregister_netevent_notifier(struct notifier_block *nb)
{
return atomic_notifier_chain_unregister(&netevent_notif_chain, nb);
}
EXPORT_SYMBOL_GPL(unregister_netevent_notifier);
/**
* call_netevent_notifiers - call all netevent notifier blocks
* @val: value passed unmodified to notifier function
* @v: pointer passed unmodified to notifier function
*
* Call all neighbour notifier blocks. Parameters and return value
* are as for notifier_call_chain().
*/
int call_netevent_notifiers(unsigned long val, void *v)
{
return atomic_notifier_call_chain(&netevent_notif_chain, val, v);
}
EXPORT_SYMBOL_GPL(call_netevent_notifiers);
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