Fix regression in the /sys/class/infiniband/.../rate attribute -- old

kernels used to just return something, even if the underlying value was
 out-of-bounds, while 3.4-rc1 returned EINVAL to userspace.  This breaks
 some applications that check for the error, so go back to the old
 behavior.
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Merge tag 'rdma-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband

Pull infiniband fixes from Roland Dreier:
 "Fix a regression in the /sys/class/infiniband/.../rate attribute --
  old kernels used to just return something, even if the underlying
  value was out-of-bounds, while 3.4-rc1 returned EINVAL to userspace.
  This breaks some applications that check for the error, so go back to
  the old behavior."

* tag 'rdma-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
  IB/core: Don't return EINVAL from sysfs rate attribute for invalid speeds
  IB/mlx4: Don't return an invalid speed when a port is down

drivers/infiniband/core/sysfs.c

@@ -179,7 +179,7 @@ static ssize_t rate_show(struct ib_port *p, struct port_attribute *unused,
 {
 	struct ib_port_attr attr;
 	char *speed = "";
-	int rate = -1;		/* in deci-Gb/sec */
+	int rate;		/* in deci-Gb/sec */
 	ssize_t ret;
 
 	ret = ib_query_port(p->ibdev, p->port_num, &attr);
@@ -187,9 +187,6 @@ static ssize_t rate_show(struct ib_port *p, struct port_attribute *unused,
 		return ret;
 
 	switch (attr.active_speed) {
-	case IB_SPEED_SDR:
-		rate = 25;
-		break;
 	case IB_SPEED_DDR:
 		speed = " DDR";
 		rate = 50;
@@ -210,6 +207,10 @@ static ssize_t rate_show(struct ib_port *p, struct port_attribute *unused,
 		speed = " EDR";
 		rate = 250;
 		break;
+	case IB_SPEED_SDR:
+	default:		/* default to SDR for invalid rates */
+		rate = 25;
+		break;
 	}
 
 	rate *= ib_width_enum_to_int(attr.active_width);

drivers/infiniband/hw/mlx4/main.c

@@ -253,6 +253,11 @@ static int ib_link_query_port(struct ib_device *ibdev, u8 port,
 		if (out_mad->data[15] & 0x1)
 			props->active_speed = IB_SPEED_FDR10;
 	}
+
+	/* Avoid wrong speed value returned by FW if the IB link is down. */
+	if (props->state == IB_PORT_DOWN)
+		 props->active_speed = IB_SPEED_SDR;
+
 out:
 	kfree(in_mad);
 	kfree(out_mad);