Re: [PATCH v4 00/54] tree-in-dcache stuff

@@ -59,7 +59,6 @@ static struct ffs_data *__must_check ffs_data_new(const char *dev_name)
 	__attribute__((malloc));
 
 /* Opened counter handling. */
-static void ffs_data_opened(struct ffs_data *ffs);
 static void ffs_data_closed(struct ffs_data *ffs);
 
 /* Called with ffs->mutex held; take over ownership of data. */

@@ -636,23 +635,25 @@ static ssize_t ffs_ep0_read(struct file *file, char __user *buf,
 	return ret;
 }
 
+
+static void ffs_data_reset(struct ffs_data *ffs);
+
 static int ffs_ep0_open(struct inode *inode, struct file *file)
 {
 	struct ffs_data *ffs = inode->i_sb->s_fs_info;
-	int ret;
 
-	/* Acquire mutex */
-	ret = ffs_mutex_lock(&ffs->mutex, file->f_flags & O_NONBLOCK);
-	if (ret < 0)
-		return ret;
-
-	ffs_data_opened(ffs);
+	spin_lock_irq(&ffs->eps_lock);
 	if (ffs->state == FFS_CLOSING) {
-		ffs_data_closed(ffs);
-		mutex_unlock(&ffs->mutex);
+		spin_unlock_irq(&ffs->eps_lock);
 		return -EBUSY;
 	}
-	mutex_unlock(&ffs->mutex);
+	if (!ffs->opened++ && ffs->state == FFS_DEACTIVATED) {
+		ffs->state = FFS_CLOSING;
+		spin_unlock_irq(&ffs->eps_lock);
+		ffs_data_reset(ffs);
+	} else {
+		spin_unlock_irq(&ffs->eps_lock);
+	}
 	file->private_data = ffs;
 
 	return stream_open(inode, file);

@@ -1202,15 +1203,10 @@ ffs_epfile_open(struct inode *inode, struct file *file)
 {
 	struct ffs_data *ffs = inode->i_sb->s_fs_info;
 	struct ffs_epfile *epfile;
-	int ret;
-
-	/* Acquire mutex */
-	ret = ffs_mutex_lock(&ffs->mutex, file->f_flags & O_NONBLOCK);
-	if (ret < 0)
-		return ret;
 
-	if (!atomic_inc_not_zero(&ffs->opened)) {
-		mutex_unlock(&ffs->mutex);
+	spin_lock_irq(&ffs->eps_lock);
+	if (!ffs->opened) {
+		spin_unlock_irq(&ffs->eps_lock);
 		return -ENODEV;
 	}
 	/*

@@ -1220,11 +1216,11 @@ ffs_epfile_open(struct inode *inode, struct file *file)
 	 */
 	epfile = smp_load_acquire(&inode->i_private);
 	if (unlikely(ffs->state != FFS_ACTIVE || !epfile)) {
-		mutex_unlock(&ffs->mutex);
-		ffs_data_closed(ffs);
+		spin_unlock_irq(&ffs->eps_lock);
 		return -ENODEV;
 	}
-	mutex_unlock(&ffs->mutex);
+	ffs->opened++;
+	spin_unlock_irq(&ffs->eps_lock);
 
 	file->private_data = epfile;
 	return stream_open(inode, file);

@@ -2092,8 +2088,6 @@ static int ffs_fs_init_fs_context(struct fs_context *fc)
 	return 0;
 }
 
-static void ffs_data_reset(struct ffs_data *ffs);
-
 static void
 ffs_fs_kill_sb(struct super_block *sb)
 {

@@ -2150,15 +2144,6 @@ static void ffs_data_get(struct ffs_data *ffs)
 	refcount_inc(&ffs->ref);
 }
 
-static void ffs_data_opened(struct ffs_data *ffs)
-{
-	if (atomic_add_return(1, &ffs->opened) == 1 &&
-			ffs->state == FFS_DEACTIVATED) {
-		ffs->state = FFS_CLOSING;
-		ffs_data_reset(ffs);
-	}
-}
-
 static void ffs_data_put(struct ffs_data *ffs)
 {
 	if (refcount_dec_and_test(&ffs->ref)) {

@@ -2176,28 +2161,29 @@ static void ffs_data_put(struct ffs_data *ffs)
 
 static void ffs_data_closed(struct ffs_data *ffs)
 {
-	if (atomic_dec_and_test(&ffs->opened)) {
-		if (ffs->no_disconnect) {
-			struct ffs_epfile *epfiles;
-			unsigned long flags;
-
-			ffs->state = FFS_DEACTIVATED;
-			spin_lock_irqsave(&ffs->eps_lock, flags);
-			epfiles = ffs->epfiles;
-			ffs->epfiles = NULL;
-			spin_unlock_irqrestore(&ffs->eps_lock,
-							flags);
-
-			if (epfiles)
-				ffs_epfiles_destroy(ffs->sb, epfiles,
-						 ffs->eps_count);
-
-			if (ffs->setup_state == FFS_SETUP_PENDING)
-				__ffs_ep0_stall(ffs);
-		} else {
-			ffs->state = FFS_CLOSING;
-			ffs_data_reset(ffs);
-		}
+	spin_lock_irq(&ffs->eps_lock);
+	if (--ffs->opened) {	// not the last opener?
+		spin_unlock_irq(&ffs->eps_lock);
+		return;
+	}
+	if (ffs->no_disconnect) {
+		struct ffs_epfile *epfiles;
+
+		ffs->state = FFS_DEACTIVATED;
+		epfiles = ffs->epfiles;
+		ffs->epfiles = NULL;
+		spin_unlock_irq(&ffs->eps_lock);
+
+		if (epfiles)
+			ffs_epfiles_destroy(ffs->sb, epfiles,
+					 ffs->eps_count);
+
+		if (ffs->setup_state == FFS_SETUP_PENDING)
+			__ffs_ep0_stall(ffs);
+	} else {
+		ffs->state = FFS_CLOSING;
+		spin_unlock_irq(&ffs->eps_lock);
+		ffs_data_reset(ffs);
 	}
 }
 

@@ -2214,7 +2200,7 @@ static struct ffs_data *ffs_data_new(const char *dev_name)
 	}
 
 	refcount_set(&ffs->ref, 1);
-	atomic_set(&ffs->opened, 0);
+	ffs->opened = 0;
 	ffs->state = FFS_READ_DESCRIPTORS;
 	mutex_init(&ffs->mutex);
 	spin_lock_init(&ffs->eps_lock);

@@ -2266,6 +2252,7 @@ static void ffs_data_reset(struct ffs_data *ffs)
 {
 	ffs_data_clear(ffs);
 
+	spin_lock_irq(&ffs->eps_lock);
 	ffs->raw_descs_data = NULL;
 	ffs->raw_descs = NULL;
 	ffs->raw_strings = NULL;

@@ -2289,6 +2276,7 @@ static void ffs_data_reset(struct ffs_data *ffs)
 	ffs->ms_os_descs_ext_prop_count = 0;
 	ffs->ms_os_descs_ext_prop_name_len = 0;
 	ffs->ms_os_descs_ext_prop_data_len = 0;
+	spin_unlock_irq(&ffs->eps_lock);
 }
 
 

@@ -3756,6 +3744,7 @@ static int ffs_func_set_alt(struct usb_function *f,
 {
 	struct ffs_function *func = ffs_func_from_usb(f);
 	struct ffs_data *ffs = func->ffs;
+	unsigned long flags;
 	int ret = 0, intf;
 
 	if (alt > MAX_ALT_SETTINGS)

@@ -3768,12 +3757,15 @@ static int ffs_func_set_alt(struct usb_function *f,
 	if (ffs->func)
 		ffs_func_eps_disable(ffs->func);
 
+	spin_lock_irqsave(&ffs->eps_lock, flags);
 	if (ffs->state == FFS_DEACTIVATED) {
 		ffs->state = FFS_CLOSING;
+		spin_unlock_irqrestore(&ffs->eps_lock, flags);
 		INIT_WORK(&ffs->reset_work, ffs_reset_work);
 		schedule_work(&ffs->reset_work);
 		return -ENODEV;
 	}
+	spin_unlock_irqrestore(&ffs->eps_lock, flags);
 
 	if (ffs->state != FFS_ACTIVE)
 		return -ENODEV;

@@ -3791,16 +3783,20 @@ static void ffs_func_disable(struct usb_function *f)
 {
 	struct ffs_function *func = ffs_func_from_usb(f);
 	struct ffs_data *ffs = func->ffs;
+	unsigned long flags;
 
 	if (ffs->func)
 		ffs_func_eps_disable(ffs->func);
 
+	spin_lock_irqsave(&ffs->eps_lock, flags);
 	if (ffs->state == FFS_DEACTIVATED) {
 		ffs->state = FFS_CLOSING;
+		spin_unlock_irqrestore(&ffs->eps_lock, flags);
 		INIT_WORK(&ffs->reset_work, ffs_reset_work);
 		schedule_work(&ffs->reset_work);
 		return;
 	}
+	spin_unlock_irqrestore(&ffs->eps_lock, flags);
 
 	if (ffs->state == FFS_ACTIVE) {
 		ffs->func = NULL;

@@ -176,7 +176,7 @@ struct ffs_data {
 	/* reference counter */
 	refcount_t			ref;
 	/* how many files are opened (EP0 and others) */
-	atomic_t			opened;
+	int				opened;
 
 	/* EP0 state */
 	enum ffs_state			state;