From: Andrew Boyer <andrew.boyer@dell.com>
Date: Mon, 5 Dec 2016 13:43:20 +0000 (-0500)
Subject: IB/rxe: Wait for tasklets to finish before tearing down QP
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=07bf9627d5f1c0334fc543a5435a31a3b5907944;p=linux-beck.git

IB/rxe: Wait for tasklets to finish before tearing down QP

The system may crash when a malformed request is received and
the error is detected by the responder.

NodeA: $ ibv_rc_pingpong -g 0 -d rxe0 -i 1 -n 1 -s 50000
NodeB: $ ibv_rc_pingpong -g 0 -d rxe0 -i 1 -n 1 -s 1024 <NodeA_ip>

The responder generates a receive error on node B since the incoming
SEND is oversized. If the client tears down the QP before the responder
or the completer finish running, a page fault may occur.

The fix makes the destroy operation spin until the tasks complete, which
appears to be original intent of the design.

Signed-off-by: Andrew Boyer <andrew.boyer@dell.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
---

diff --git a/drivers/infiniband/sw/rxe/rxe_task.c b/drivers/infiniband/sw/rxe/rxe_task.c
index 1e19bf828a6e..d2a14a1bdc7f 100644
--- a/drivers/infiniband/sw/rxe/rxe_task.c
+++ b/drivers/infiniband/sw/rxe/rxe_task.c
@@ -121,6 +121,7 @@ int rxe_init_task(void *obj, struct rxe_task *task,
 	task->arg	= arg;
 	task->func	= func;
 	snprintf(task->name, sizeof(task->name), "%s", name);
+	task->destroyed	= false;
 
 	tasklet_init(&task->tasklet, rxe_do_task, (unsigned long)task);
 
@@ -132,11 +133,29 @@ int rxe_init_task(void *obj, struct rxe_task *task,
 
 void rxe_cleanup_task(struct rxe_task *task)
 {
+	unsigned long flags;
+	bool idle;
+
+	/*
+	 * Mark the task, then wait for it to finish. It might be
+	 * running in a non-tasklet (direct call) context.
+	 */
+	task->destroyed = true;
+
+	do {
+		spin_lock_irqsave(&task->state_lock, flags);
+		idle = (task->state == TASK_STATE_START);
+		spin_unlock_irqrestore(&task->state_lock, flags);
+	} while (!idle);
+
 	tasklet_kill(&task->tasklet);
 }
 
 void rxe_run_task(struct rxe_task *task, int sched)
 {
+	if (task->destroyed)
+		return;
+
 	if (sched)
 		tasklet_schedule(&task->tasklet);
 	else
diff --git a/drivers/infiniband/sw/rxe/rxe_task.h b/drivers/infiniband/sw/rxe/rxe_task.h
index d14aa6daed05..08ff42d451c6 100644
--- a/drivers/infiniband/sw/rxe/rxe_task.h
+++ b/drivers/infiniband/sw/rxe/rxe_task.h
@@ -54,6 +54,7 @@ struct rxe_task {
 	int			(*func)(void *arg);
 	int			ret;
 	char			name[16];
+	bool			destroyed;
 };
 
 /*