4 files changed, 64 insertions, 26 deletions

diff --git a/drivers/net/wimax/i2400m/driver.c b/drivers/net/wimax/i2400m/driver.c
index a0ae19966c0c..6280646d7d7f 100644
--- a/drivers/net/wimax/i2400m/driver.c
+++ b/drivers/net/wimax/i2400m/driver.c
@@ -455,6 +455,8 @@ retry:
 	result = i2400m->bus_dev_start(i2400m);
 	if (result < 0)
 		goto error_bus_dev_start;
+	i2400m->ready = 1;
+	wmb();		/* see i2400m->ready's documentation  */
 	result = i2400m_firmware_check(i2400m);	/* fw versions ok? */
 	if (result < 0)
 		goto error_fw_check;
@@ -462,7 +464,6 @@ retry:
 	result = i2400m_check_mac_addr(i2400m);
 	if (result < 0)
 		goto error_check_mac_addr;
-	i2400m->ready = 1;
 	wimax_state_change(wimax_dev, WIMAX_ST_UNINITIALIZED);
 	result = i2400m_dev_initialize(i2400m);
 	if (result < 0)
@@ -475,6 +476,9 @@ retry:
 
 error_dev_initialize:
 error_check_mac_addr:
+	i2400m->ready = 0;
+	wmb();		/* see i2400m->ready's documentation  */
+	flush_workqueue(i2400m->work_queue);
 error_fw_check:
 	i2400m->bus_dev_stop(i2400m);
 error_bus_dev_start:
@@ -498,11 +502,15 @@ error_bootstrap:
 static
 int i2400m_dev_start(struct i2400m *i2400m, enum i2400m_bri bm_flags)
 {
-	int result;
+	int result = 0;
 	mutex_lock(&i2400m->init_mutex);	/* Well, start the device */
-	result = __i2400m_dev_start(i2400m, bm_flags);
-	if (result >= 0)
-		i2400m->updown = 1;
+	if (i2400m->updown == 0) {
+		result = __i2400m_dev_start(i2400m, bm_flags);
+		if (result >= 0) {
+			i2400m->updown = 1;
+			wmb();	/* see i2400m->updown's documentation */
+		}
+	}
 	mutex_unlock(&i2400m->init_mutex);
 	return result;
 }
@@ -529,7 +537,14 @@ void __i2400m_dev_stop(struct i2400m *i2400m)
 	wimax_state_change(wimax_dev, __WIMAX_ST_QUIESCING);
 	i2400m_net_wake_stop(i2400m);
 	i2400m_dev_shutdown(i2400m);
-	i2400m->ready = 0;
+	/*
+	 * Make sure no report hooks are running *before* we stop the
+	 * communication infrastructure with the device.
+	 */
+	i2400m->ready = 0;	/* nobody can queue work anymore */
+	wmb();		/* see i2400m->ready's documentation  */
+	flush_workqueue(i2400m->work_queue);
+
 	i2400m->bus_dev_stop(i2400m);
 	destroy_workqueue(i2400m->work_queue);
 	i2400m_rx_release(i2400m);
@@ -551,6 +566,7 @@ void i2400m_dev_stop(struct i2400m *i2400m)
 	if (i2400m->updown) {
 		__i2400m_dev_stop(i2400m);
 		i2400m->updown = 0;
+		wmb();	/* see i2400m->updown's documentation  */
 	}
 	mutex_unlock(&i2400m->init_mutex);
 }
@@ -632,7 +648,6 @@ void __i2400m_dev_reset_handle(struct work_struct *ws)
 	const char *reason;
 	struct i2400m *i2400m = iw->i2400m;
 	struct device *dev = i2400m_dev(i2400m);
-	enum wimax_st wimax_state;
 	struct i2400m_reset_ctx *ctx = i2400m->reset_ctx;
 
 	if (WARN_ON(iw->pl_size != sizeof(reason)))
@@ -647,29 +662,28 @@ void __i2400m_dev_reset_handle(struct work_struct *ws)
 		/* We are still in i2400m_dev_start() [let it fail] or
 		 * i2400m_dev_stop() [we are shutting down anyway, so
 		 * ignore it] or we are resetting somewhere else. */
-		dev_err(dev, "device rebooted\n");
+		dev_err(dev, "device rebooted somewhere else?\n");
 		i2400m_msg_to_dev_cancel_wait(i2400m, -EL3RST);
 		complete(&i2400m->msg_completion);
 		goto out;
 	}
-	wimax_state = wimax_state_get(&i2400m->wimax_dev);
-	if (wimax_state < WIMAX_ST_UNINITIALIZED) {
-		dev_info(dev, "%s: it is down, ignoring\n", reason);
-		goto out_unlock;	/* ifconfig up/down wasn't called */
+	if (i2400m->updown == 0)  {
+		dev_info(dev, "%s: device is down, doing nothing\n", reason);
+		goto out_unlock;
 	}
 	dev_err(dev, "%s: reinitializing driver\n", reason);
 	__i2400m_dev_stop(i2400m);
-	i2400m->updown = 0;
 	result = __i2400m_dev_start(i2400m,
 				    I2400M_BRI_SOFT | I2400M_BRI_MAC_REINIT);
 	if (result < 0) {
+		i2400m->updown = 0;
+		wmb();		/* see i2400m->updown's documentation  */
 		dev_err(dev, "%s: cannot start the device: %d\n",
 			reason, result);
 		result = i2400m->bus_reset(i2400m, I2400M_RT_BUS);
 		if (result >= 0)
 			result = -ENODEV;
-	} else
-		i2400m->updown = 1;
+	}
 out_unlock:
 	if (i2400m->reset_ctx) {
 		ctx->result = result;
diff --git a/drivers/net/wimax/i2400m/i2400m.h b/drivers/net/wimax/i2400m/i2400m.h
index 2b9c400810b5..fbc156db5bfd 100644
--- a/drivers/net/wimax/i2400m/i2400m.h
+++ b/drivers/net/wimax/i2400m/i2400m.h
@@ -307,6 +307,27 @@ struct i2400m_barker_db;
  *     force this to be the first field so that we can get from
  *     netdev_priv() the right pointer.
  *
+ * @updown: the device is up and ready for transmitting control and
+ *     data packets. This implies @ready (communication infrastructure
+ *     with the device is ready) and the device's firmware has been
+ *     loaded and the device initialized.
+ *
+ *     Write to it only inside a i2400m->init_mutex protected area
+ *     followed with a wmb(); rmb() before accesing (unless locked
+ *     inside i2400m->init_mutex). Read access can be loose like that
+ *     [just using rmb()] because the paths that use this also do
+ *     other error checks later on.
+ *
+ * @ready: Communication infrastructure with the device is ready, data
+ *     frames can start to be passed around (this is lighter than
+ *     using the WiMAX state for certain hot paths).
+ *
+ *     Write to it only inside a i2400m->init_mutex protected area
+ *     followed with a wmb(); rmb() before accesing (unless locked
+ *     inside i2400m->init_mutex). Read access can be loose like that
+ *     [just using rmb()] because the paths that use this also do
+ *     other error checks later on.
+ *
  * @rx_reorder: 1 if RX reordering is enabled; this can only be
  *     set at probe time.
  *
@@ -458,7 +479,7 @@ struct i2400m {
 	unsigned updown:1;		/* Network device is up or down */
 	unsigned boot_mode:1;		/* is the device in boot mode? */
 	unsigned sboot:1;		/* signed or unsigned fw boot */
-	unsigned ready:1;		/* all probing steps done */
+	unsigned ready:1;		/* Device comm infrastructure ready */
 	unsigned rx_reorder:1;		/* RX reorder is enabled */
 	u8 trace_msg_from_user;		/* echo rx msgs to 'trace' pipe */
 					/* typed u8 so /sys/kernel/debug/u8 can tweak */
diff --git a/drivers/net/wimax/i2400m/rx.c b/drivers/net/wimax/i2400m/rx.c
index bcd411f1a854..82c200ad9fdc 100644
--- a/drivers/net/wimax/i2400m/rx.c
+++ b/drivers/net/wimax/i2400m/rx.c
@@ -177,8 +177,7 @@ void i2400m_report_hook_work(struct work_struct *ws)
 	struct i2400m_work *iw =
 		container_of(ws, struct i2400m_work, ws);
 	struct i2400m_report_hook_args *args = (void *) iw->pl;
-	if (iw->i2400m->ready)
-		i2400m_report_hook(iw->i2400m, args->l3l4_hdr, args->size);
+	i2400m_report_hook(iw->i2400m, args->l3l4_hdr, args->size);
 	kfree_skb(args->skb_rx);
 	i2400m_put(iw->i2400m);
 	kfree(iw);
@@ -305,11 +304,12 @@ void i2400m_rx_ctl(struct i2400m *i2400m, struct sk_buff *skb_rx,
 			.l3l4_hdr = l3l4_hdr,
 			.size = size
 		};
-		if (unlikely(i2400m->ready == 0))	/* only send if up */
-			return;
-		skb_get(skb_rx);
-		i2400m_queue_work(i2400m, i2400m_report_hook_work,
-				  GFP_KERNEL, &args, sizeof(args));
+		rmb();		/* see i2400m->ready's documentation  */
+		if (likely(i2400m->ready)) {	/* only send if up */
+			skb_get(skb_rx);
+			i2400m_queue_work(i2400m, i2400m_report_hook_work,
+					  GFP_KERNEL, &args, sizeof(args));
+		}
 		if (unlikely(i2400m->trace_msg_from_user))
 			wimax_msg(&i2400m->wimax_dev, "echo",
 				  l3l4_hdr, size, GFP_KERNEL);
@@ -363,8 +363,6 @@ void i2400m_rx_trace(struct i2400m *i2400m,
 		 msg_type & I2400M_MT_REPORT_MASK ? "REPORT" : "CMD/SET/GET",
 		 msg_type, size);
 	d_dump(2, dev, l3l4_hdr, size);
-	if (unlikely(i2400m->ready == 0))	/* only send if up */
-		return;
 	result = wimax_msg(wimax_dev, "trace", l3l4_hdr, size, GFP_KERNEL);
 	if (result < 0)
 		dev_err(dev, "error sending trace to userspace: %d\n",
diff --git a/drivers/net/wimax/i2400m/usb.c b/drivers/net/wimax/i2400m/usb.c
index 07653ded6c59..f4dfb60bb628 100644
--- a/drivers/net/wimax/i2400m/usb.c
+++ b/drivers/net/wimax/i2400m/usb.c
@@ -516,7 +516,10 @@ void i2400mu_disconnect(struct usb_interface *iface)
  * So at the end, the three cases require common handling.
  *
  * If at the time of this call the device's firmware is not loaded,
- * nothing has to be done.
+ * nothing has to be done. Note we can be "loose" about not reading
+ * i2400m->updown under i2400m->init_mutex. If it happens to change
+ * inmediately, other parts of the call flow will fail and effectively
+ * catch it.
  *
  * If the firmware is loaded, we need to:
  *
@@ -555,6 +558,7 @@ int i2400mu_suspend(struct usb_interface *iface, pm_message_t pm_msg)
 #endif
 
 	d_fnstart(3, dev, "(iface %p pm_msg %u)\n", iface, pm_msg.event);
+	rmb();		/* see i2400m->updown's documentation  */
 	if (i2400m->updown == 0)
 		goto no_firmware;
 	if (i2400m->state == I2400M_SS_DATA_PATH_CONNECTED && is_autosuspend) {
@@ -608,6 +612,7 @@ int i2400mu_resume(struct usb_interface *iface)
 	struct i2400m *i2400m = &i2400mu->i2400m;
 
 	d_fnstart(3, dev, "(iface %p)\n", iface);
+	rmb();		/* see i2400m->updown's documentation  */
 	if (i2400m->updown == 0) {
 		d_printf(1, dev, "fw was down, no resume neeed\n");
 		goto out;