linux-kernel - [PATCH 4.6 011/203] IB/cm: Fix a recently introduced locking bug

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Date:	Mon, 25 Jul 2016 13:53:46 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Bart Van Assche <bart.vanassche@...disk.com>,
	Erez Shitrit <erezsh@...lanox.com>,
	Sean Hefty <sean.hefty@...el.com>,
	Nikolay Borisov <kernel@...p.com>,
	Doug Ledford <dledford@...hat.com>
Subject: [PATCH 4.6 011/203] IB/cm: Fix a recently introduced locking bug

4.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanassche@...disk.com>

commit 943f44d94aa26bfdcaafc40d3701e24eeb58edce upstream.

ib_cm_notify() can be called from interrupt context. Hence do not
reenable interrupts unconditionally in cm_establish().

This patch avoids that lockdep reports the following warning:

WARNING: CPU: 0 PID: 23317 at kernel/locking/lockdep.c:2624 trace _hardirqs_on_caller+0x112/0x1b0
DEBUG_LOCKS_WARN_ON(current->hardirq_context)
Call Trace:
 <IRQ>  [<ffffffff812bd0e5>] dump_stack+0x67/0x92
 [<ffffffff81056f21>] __warn+0xc1/0xe0
 [<ffffffff81056f8a>] warn_slowpath_fmt+0x4a/0x50
 [<ffffffff810a5932>] trace_hardirqs_on_caller+0x112/0x1b0
 [<ffffffff810a59dd>] trace_hardirqs_on+0xd/0x10
 [<ffffffff815992c7>] _raw_spin_unlock_irq+0x27/0x40
 [<ffffffffa0382e9c>] ib_cm_notify+0x25c/0x290 [ib_cm]
 [<ffffffffa068fbc1>] srpt_qp_event+0xa1/0xf0 [ib_srpt]
 [<ffffffffa04efb97>] mlx4_ib_qp_event+0x67/0xd0 [mlx4_ib]
 [<ffffffffa034ec0a>] mlx4_qp_event+0x5a/0xc0 [mlx4_core]
 [<ffffffffa03365f8>] mlx4_eq_int+0x3d8/0xcf0 [mlx4_core]
 [<ffffffffa0336f9c>] mlx4_msi_x_interrupt+0xc/0x20 [mlx4_core]
 [<ffffffff810b0914>] handle_irq_event_percpu+0x64/0x100
 [<ffffffff810b09e4>] handle_irq_event+0x34/0x60
 [<ffffffff810b3a6a>] handle_edge_irq+0x6a/0x150
 [<ffffffff8101ad05>] handle_irq+0x15/0x20
 [<ffffffff8101a66c>] do_IRQ+0x5c/0x110
 [<ffffffff8159a2c9>] common_interrupt+0x89/0x89
 [<ffffffff81297a17>] blk_run_queue_async+0x37/0x40
 [<ffffffffa0163e53>] rq_completed+0x43/0x70 [dm_mod]
 [<ffffffffa0164896>] dm_softirq_done+0x176/0x280 [dm_mod]
 [<ffffffff812a26c2>] blk_done_softirq+0x52/0x90
 [<ffffffff8105bc1f>] __do_softirq+0x10f/0x230
 [<ffffffff8105bec8>] irq_exit+0xa8/0xb0
 [<ffffffff8103653e>] smp_trace_call_function_single_interrupt+0x2e/0x30
 [<ffffffff81036549>] smp_call_function_single_interrupt+0x9/0x10
 [<ffffffff8159a959>] call_function_single_interrupt+0x89/0x90
 <EOI>

Fixes: commit be4b499323bf (IB/cm: Do not queue work to a device that's going away)
Signed-off-by: Bart Van Assche <bart.vanassche@...disk.com>
Cc: Erez Shitrit <erezsh@...lanox.com>
Cc: Sean Hefty <sean.hefty@...el.com>
Cc: Nikolay Borisov <kernel@...p.com>
Acked-by: Erez Shitrit <erezsh@...lanox.com>
Signed-off-by: Doug Ledford <dledford@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/infiniband/core/cm.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -3452,14 +3452,14 @@ static int cm_establish(struct ib_cm_id
 	work->cm_event.event = IB_CM_USER_ESTABLISHED;
 
 	/* Check if the device started its remove_one */
-	spin_lock_irq(&cm.lock);
+	spin_lock_irqsave(&cm.lock, flags);
 	if (!cm_dev->going_down) {
 		queue_delayed_work(cm.wq, &work->work, 0);
 	} else {
 		kfree(work);
 		ret = -ENODEV;
 	}
-	spin_unlock_irq(&cm.lock);
+	spin_unlock_irqrestore(&cm.lock, flags);
 
 out:
 	return ret;