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
op-state-get.c
/*
* Linux WiMAX
* Implement and export a method for getting a WiMAX device current state
*
* Copyright (C) 2009 Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
*
* Based on previous WiMAX core work by:
* Copyright (C) 2008 Intel Corporation <linux-wimax@intel.com>
* Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#include <net/wimax.h>
#include <net/genetlink.h>
#include <linux/wimax.h>
#include <linux/security.h>
#include "wimax-internal.h"
#define D_SUBMODULE op_state_get
#include "debug-levels.h"
/*
* Exporting to user space over generic netlink
*
* Parse the state get command from user space, return a combination
* value that describe the current state.
*
* No attributes.
*/
int wimax_gnl_doit_state_get(struct sk_buff *skb, struct genl_info *info)
{
int result, ifindex;
struct wimax_dev *wimax_dev;
d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
result = -ENODEV;
if (info->attrs[WIMAX_GNL_STGET_IFIDX] == NULL) {
pr_err("WIMAX_GNL_OP_STATE_GET: can't find IFIDX attribute\n");
goto error_no_wimax_dev;
}
ifindex = nla_get_u32(info->attrs[WIMAX_GNL_STGET_IFIDX]);
wimax_dev = wimax_dev_get_by_genl_info(info, ifindex);
if (wimax_dev == NULL)
goto error_no_wimax_dev;
/* Execute the operation and send the result back to user space */
result = wimax_state_get(wimax_dev);
dev_put(wimax_dev->net_dev);
error_no_wimax_dev:
d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
return result;
}
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