From cb6d96294dcdfbebac2c4e7e4d6f2cd884f60364 Mon Sep 17 00:00:00 2001
From: Michal Nazarewicz <mina86@mina86.com>
Date: Mon, 9 Dec 2013 15:55:36 -0800
Subject: [PATCH] usb: gadget: f_fs: remove loop from I/O function

When endpoint changes (due to it being disabled or alt setting changed),
mimic the action as if the change happened after the request has been
queued, instead of retrying with the new endpoint.

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Cc: David Cohen <david.a.cohen@linux.intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
---
 drivers/usb/gadget/f_fs.c | 94 ++++++++++++++++++++---------------------------
 1 file changed, 40 insertions(+), 54 deletions(-)

diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index c3067f4..b4c8e2f 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -758,73 +758,59 @@ static ssize_t ffs_epfile_io(struct file *file,
 	ssize_t ret;
 	int halt;
 
-	goto first_try;
-	do {
-		spin_unlock_irq(&epfile->ffs->eps_lock);
-		mutex_unlock(&epfile->mutex);
+	/* Are we still active? */
+	if (WARN_ON(epfile->ffs->state != FFS_ACTIVE)) {
+		ret = -ENODEV;
+		goto error;
+	}
 
-first_try:
-		/* Are we still active? */
-		if (WARN_ON(epfile->ffs->state != FFS_ACTIVE)) {
-			ret = -ENODEV;
+	/* Wait for endpoint to be enabled */
+	ep = epfile->ep;
+	if (!ep) {
+		if (file->f_flags & O_NONBLOCK) {
+			ret = -EAGAIN;
 			goto error;
 		}
 
-		/* Wait for endpoint to be enabled */
-		ep = epfile->ep;
-		if (!ep) {
-			if (file->f_flags & O_NONBLOCK) {
-				ret = -EAGAIN;
-				goto error;
-			}
-
-			if (wait_event_interruptible(epfile->wait,
-						     (ep = epfile->ep))) {
-				ret = -EINTR;
-				goto error;
-			}
-		}
-
-		/* Do we halt? */
-		halt = !read == !epfile->in;
-		if (halt && epfile->isoc) {
-			ret = -EINVAL;
+		ret = wait_event_interruptible(epfile->wait, (ep = epfile->ep));
+		if (ret) {
+			ret = -EINTR;
 			goto error;
 		}
+	}
 
-		/* Allocate & copy */
-		if (!halt && !data) {
-			data = kzalloc(len, GFP_KERNEL);
-			if (unlikely(!data))
-				return -ENOMEM;
+	/* Do we halt? */
+	halt = !read == !epfile->in;
+	if (halt && epfile->isoc) {
+		ret = -EINVAL;
+		goto error;
+	}
 
-			if (!read &&
-			    unlikely(__copy_from_user(data, buf, len))) {
-				ret = -EFAULT;
-				goto error;
-			}
-		}
+	/* Allocate & copy */
+	if (!halt) {
+		data = kmalloc(len, GFP_KERNEL);
+		if (unlikely(!data))
+			return -ENOMEM;
 
-		/* We will be using request */
-		ret = ffs_mutex_lock(&epfile->mutex,
-				     file->f_flags & O_NONBLOCK);
-		if (unlikely(ret))
+		if (!read && unlikely(copy_from_user(data, buf, len))) {
+			ret = -EFAULT;
 			goto error;
+		}
+	}
 
-		/*
-		 * We're called from user space, we can use _irq rather then
-		 * _irqsave
-		 */
-		spin_lock_irq(&epfile->ffs->eps_lock);
+	/* We will be using request */
+	ret = ffs_mutex_lock(&epfile->mutex, file->f_flags & O_NONBLOCK);
+	if (unlikely(ret))
+		goto error;
 
-		/*
-		 * While we were acquiring mutex endpoint got disabled
-		 * or changed?
-		 */
-	} while (unlikely(epfile->ep != ep));
+	spin_lock_irq(&epfile->ffs->eps_lock);
 
-	/* Halt */
-	if (unlikely(halt)) {
+	if (epfile->ep != ep) {
+		/* In the meantime, endpoint got disabled or changed. */
+		ret = -ESHUTDOWN;
+		spin_unlock_irq(&epfile->ffs->eps_lock);
+	} else if (halt) {
+		/* Halt */
 		if (likely(epfile->ep == ep) && !WARN_ON(!ep->ep))
 			usb_ep_set_halt(ep->ep);
 		spin_unlock_irq(&epfile->ffs->eps_lock);
-- 
2.7.4