usb: musb: Fix sleeping function called from invalid context for hdrc glue

Commit 65b3f50e ("usb: musb: Add PM runtime support for MUSB DSPS
glue layer") wrongly added a call for pm_runtime_get_sync to otg_timer
that runs in softirq context. That causes a "BUG: sleeping function called
from invalid context" every time when polling the cable status:

[<c015ebb4>] (__might_sleep) from [<c0413d60>] (__pm_runtime_resume+0x9c/0xa0)
[<c0413d60>] (__pm_runtime_resume) from [<c04d0bc4>] (otg_timer+0x3c/0x254)
[<c04d0bc4>] (otg_timer) from [<c0191180>] (call_timer_fn+0xfc/0x41c)
[<c0191180>] (call_timer_fn) from [<c01915c0>] (expire_timers+0x120/0x210)
[<c01915c0>] (expire_timers) from [<c0191acc>] (run_timer_softirq+0xa4/0xdc)
[<c0191acc>] (run_timer_softirq) from [<c010168c>] (__do_softirq+0x12c/0x594)

I did not notice that as I did not have CONFIG_DEBUG_ATOMIC_SLEEP enabled.
And looks like also musb_gadget_queue() suffers from the same problem.

Let's fix the issue by using a list of delayed work then call it on
resume. Note that we want to do this only when musb core and it's
parent devices are awake, and we need to make sure the DSPS glue
timer is stopped as noted by Johan Hovold <johan@kernel.org>.
Note that we already are re-enabling the timer with mod_timer() in
dsps_musb_enable().

Later on we may be able to remove other delayed work in the musb driver
and just do it from pending_resume_work. But this should be done only
for delayed work that does not have other timing requirements beyond
just being run on resume.

Fixes: 65b3f50e ("usb: musb: Add PM runtime support for MUSB DSPS
glue layer")
Reported-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Johan Hovold <johan@kernel.org>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/musb_core.c

@@ -1969,6 +1969,7 @@ static struct musb *allocate_instance(struct device *dev,
 	INIT_LIST_HEAD(&musb->control);
 	INIT_LIST_HEAD(&musb->in_bulk);
 	INIT_LIST_HEAD(&musb->out_bulk);
+	INIT_LIST_HEAD(&musb->pending_list);
 
 	musb->vbuserr_retry = VBUSERR_RETRY_COUNT;
 	musb->a_wait_bcon = OTG_TIME_A_WAIT_BCON;
@@ -2018,6 +2019,84 @@ static void musb_free(struct musb *musb)
 	musb_host_free(musb);
 }
 
+struct musb_pending_work {
+	int (*callback)(struct musb *musb, void *data);
+	void *data;
+	struct list_head node;
+};
+
+/*
+ * Called from musb_runtime_resume(), musb_resume(), and
+ * musb_queue_resume_work(). Callers must take musb->lock.
+ */
+static int musb_run_resume_work(struct musb *musb)
+{
+	struct musb_pending_work *w, *_w;
+	unsigned long flags;
+	int error = 0;
+
+	spin_lock_irqsave(&musb->list_lock, flags);
+	list_for_each_entry_safe(w, _w, &musb->pending_list, node) {
+		if (w->callback) {
+			error = w->callback(musb, w->data);
+			if (error < 0) {
+				dev_err(musb->controller,
+					"resume callback %p failed: %i\n",
+					w->callback, error);
+			}
+		}
+		list_del(&w->node);
+		devm_kfree(musb->controller, w);
+	}
+	spin_unlock_irqrestore(&musb->list_lock, flags);
+
+	return error;
+}
+
+/*
+ * Called to run work if device is active or else queue the work to happen
+ * on resume. Caller must take musb->lock and must hold an RPM reference.
+ *
+ * Note that we cowardly refuse queuing work after musb PM runtime
+ * resume is done calling musb_run_resume_work() and return -EINPROGRESS
+ * instead.
+ */
+int musb_queue_resume_work(struct musb *musb,
+			   int (*callback)(struct musb *musb, void *data),
+			   void *data)
+{
+	struct musb_pending_work *w;
+	unsigned long flags;
+	int error;
+
+	if (WARN_ON(!callback))
+		return -EINVAL;
+
+	if (pm_runtime_active(musb->controller))
+		return callback(musb, data);
+
+	w = devm_kzalloc(musb->controller, sizeof(*w), GFP_ATOMIC);
+	if (!w)
+		return -ENOMEM;
+
+	w->callback = callback;
+	w->data = data;
+	spin_lock_irqsave(&musb->list_lock, flags);
+	if (musb->is_runtime_suspended) {
+		list_add_tail(&w->node, &musb->pending_list);
+		error = 0;
+	} else {
+		dev_err(musb->controller, "could not add resume work %p\n",
+			callback);
+		devm_kfree(musb->controller, w);
+		error = -EINPROGRESS;
+	}
+	spin_unlock_irqrestore(&musb->list_lock, flags);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(musb_queue_resume_work);
+
 static void musb_deassert_reset(struct work_struct *work)
 {
 	struct musb *musb;
@@ -2065,6 +2144,7 @@ musb_init_controller(struct device *dev, int nIrq, void __iomem *ctrl)
 	}
 
 	spin_lock_init(&musb->lock);
+	spin_lock_init(&musb->list_lock);
 	musb->board_set_power = plat->set_power;
 	musb->min_power = plat->min_power;
 	musb->ops = plat->platform_ops;
@@ -2558,6 +2638,7 @@ static int musb_suspend(struct device *dev)
 
 	musb_platform_disable(musb);
 	musb_generic_disable(musb);
+	WARN_ON(!list_empty(&musb->pending_list));
 
 	spin_lock_irqsave(&musb->lock, flags);
 
@@ -2580,6 +2661,8 @@ static int musb_suspend(struct device *dev)
 static int musb_resume(struct device *dev)
 {
 	struct musb *musb = dev_to_musb(dev);
+	unsigned long flags;
+	int error;
 	u8 devctl;
 	u8 mask;
 
@@ -2615,6 +2698,13 @@ static int musb_resume(struct device *dev)
 
 	musb_start(musb);
 
+	spin_lock_irqsave(&musb->lock, flags);
+	error = musb_run_resume_work(musb);
+	if (error)
+		dev_err(musb->controller, "resume work failed with %i\n",
+			error);
+	spin_unlock_irqrestore(&musb->lock, flags);
+
 	return 0;
 }
 
@@ -2623,6 +2713,7 @@ static int musb_runtime_suspend(struct device *dev)
 	struct musb	*musb = dev_to_musb(dev);
 
 	musb_save_context(musb);
+	musb->is_runtime_suspended = 1;
 
 	return 0;
 }
@@ -2630,6 +2721,8 @@ static int musb_runtime_suspend(struct device *dev)
 static int musb_runtime_resume(struct device *dev)
 {
 	struct musb *musb = dev_to_musb(dev);
+	unsigned long flags;
+	int error;
 
 	/*
 	 * When pm_runtime_get_sync called for the first time in driver
@@ -2651,6 +2744,14 @@ static int musb_runtime_resume(struct device *dev)
 				msecs_to_jiffies(USB_RESUME_TIMEOUT));
 	}
 
+	spin_lock_irqsave(&musb->lock, flags);
+	error = musb_run_resume_work(musb);
+	if (error)
+		dev_err(musb->controller, "resume work failed with %i\n",
+			error);
+	musb->is_runtime_suspended = 0;
+	spin_unlock_irqrestore(&musb->lock, flags);
+
 	return 0;
 }
 

drivers/usb/musb/musb_core.h

@@ -303,6 +303,7 @@ struct musb_context_registers {
 struct musb {
 	/* device lock */
 	spinlock_t		lock;
+	spinlock_t		list_lock;	/* resume work list lock */
 
 	struct musb_io		io;
 	const struct musb_platform_ops *ops;
@@ -337,6 +338,7 @@ struct musb {
 	struct list_head	control;	/* of musb_qh */
 	struct list_head	in_bulk;	/* of musb_qh */
 	struct list_head	out_bulk;	/* of musb_qh */
+	struct list_head	pending_list;	/* pending work list */
 
 	struct timer_list	otg_timer;
 	struct notifier_block	nb;
@@ -386,6 +388,7 @@ struct musb {
 	unsigned long		idle_timeout;	/* Next timeout in jiffies */
 
 	unsigned		is_initialized:1;
+	unsigned		is_runtime_suspended:1;
 
 	/* active means connected and not suspended */
 	unsigned		is_active:1;
@@ -542,6 +545,10 @@ extern irqreturn_t musb_interrupt(struct musb *);
 
 extern void musb_hnp_stop(struct musb *musb);
 
+int musb_queue_resume_work(struct musb *musb,
+			   int (*callback)(struct musb *musb, void *data),
+			   void *data);
+
 static inline void musb_platform_set_vbus(struct musb *musb, int is_on)
 {
 	if (musb->ops->set_vbus)

drivers/usb/musb/musb_dsps.c

@@ -185,24 +185,19 @@ static void dsps_musb_disable(struct musb *musb)
 	musb_writel(reg_base, wrp->coreintr_clear, wrp->usb_bitmap);
 	musb_writel(reg_base, wrp->epintr_clear,
 			 wrp->txep_bitmap | wrp->rxep_bitmap);
+	del_timer_sync(&glue->timer);
 	musb_writeb(musb->mregs, MUSB_DEVCTL, 0);
 }
 
-static void otg_timer(unsigned long _musb)
+/* Caller must take musb->lock */
+static int dsps_check_status(struct musb *musb, void *unused)
 {
-	struct musb *musb = (void *)_musb;
 	void __iomem *mregs = musb->mregs;
 	struct device *dev = musb->controller;
 	struct dsps_glue *glue = dev_get_drvdata(dev->parent);
 	const struct dsps_musb_wrapper *wrp = glue->wrp;
 	u8 devctl;
-	unsigned long flags;
 	int skip_session = 0;
-	int err;
-
-	err = pm_runtime_get_sync(dev);
-	if (err < 0)
-		dev_err(dev, "Poll could not pm_runtime_get: %i\n", err);
 
 	/*
 	 * We poll because DSPS IP's won't expose several OTG-critical
@@ -212,7 +207,6 @@ static void otg_timer(unsigned long _musb)
 	dev_dbg(musb->controller, "Poll devctl %02x (%s)\n", devctl,
 				usb_otg_state_string(musb->xceiv->otg->state));
 
-	spin_lock_irqsave(&musb->lock, flags);
 	switch (musb->xceiv->otg->state) {
 	case OTG_STATE_A_WAIT_VRISE:
 		mod_timer(&glue->timer, jiffies +
@@ -245,8 +239,30 @@ static void otg_timer(unsigned long _musb)
 	default:
 		break;
 	}
-	spin_unlock_irqrestore(&musb->lock, flags);
 
+	return 0;
+}
+
+static void otg_timer(unsigned long _musb)
+{
+	struct musb *musb = (void *)_musb;
+	struct device *dev = musb->controller;
+	unsigned long flags;
+	int err;
+
+	err = pm_runtime_get(dev);
+	if ((err != -EINPROGRESS) && err < 0) {
+		dev_err(dev, "Poll could not pm_runtime_get: %i\n", err);
+		pm_runtime_put_noidle(dev);
+
+		return;
+	}
+
+	spin_lock_irqsave(&musb->lock, flags);
+	err = musb_queue_resume_work(musb, dsps_check_status, NULL);
+	if (err < 0)
+		dev_err(dev, "%s resume work: %i\n", __func__, err);
+	spin_unlock_irqrestore(&musb->lock, flags);
 	pm_runtime_mark_last_busy(dev);
 	pm_runtime_put_autosuspend(dev);
 }

drivers/usb/musb/musb_gadget.c

@@ -1222,13 +1222,22 @@ void musb_ep_restart(struct musb *musb, struct musb_request *req)
 		rxstate(musb, req);
 }
 
+static int musb_ep_restart_resume_work(struct musb *musb, void *data)
+{
+	struct musb_request *req = data;
+
+	musb_ep_restart(musb, req);
+
+	return 0;
+}
+
 static int musb_gadget_queue(struct usb_ep *ep, struct usb_request *req,
 			gfp_t gfp_flags)
 {
 	struct musb_ep		*musb_ep;
 	struct musb_request	*request;
 	struct musb		*musb;
-	int			status = 0;
+	int			status;
 	unsigned long		lockflags;
 
 	if (!ep || !req)
@@ -1245,6 +1254,17 @@ static int musb_gadget_queue(struct usb_ep *ep, struct usb_request *req,
 	if (request->ep != musb_ep)
 		return -EINVAL;
 
+	status = pm_runtime_get(musb->controller);
+	if ((status != -EINPROGRESS) && status < 0) {
+		dev_err(musb->controller,
+			"pm runtime get failed in %s\n",
+			__func__);
+		pm_runtime_put_noidle(musb->controller);
+
+		return status;
+	}
+	status = 0;
+
 	trace_musb_req_enq(request);
 
 	/* request is mine now... */
@@ -1255,7 +1275,6 @@ static int musb_gadget_queue(struct usb_ep *ep, struct usb_request *req,
 
 	map_dma_buffer(request, musb, musb_ep);
 
-	pm_runtime_get_sync(musb->controller);
 	spin_lock_irqsave(&musb->lock, lockflags);
 
 	/* don't queue if the ep is down */
@@ -1271,8 +1290,14 @@ static int musb_gadget_queue(struct usb_ep *ep, struct usb_request *req,
 	list_add_tail(&request->list, &musb_ep->req_list);
 
 	/* it this is the head of the queue, start i/o ... */
-	if (!musb_ep->busy && &request->list == musb_ep->req_list.next)
-		musb_ep_restart(musb, request);
+	if (!musb_ep->busy && &request->list == musb_ep->req_list.next) {
+		status = musb_queue_resume_work(musb,
+						musb_ep_restart_resume_work,
+						request);
+		if (status < 0)
+			dev_err(musb->controller, "%s resume work: %i\n",
+				__func__, status);
+	}
 
 unlock:
 	spin_unlock_irqrestore(&musb->lock, lockflags);