usb: gadget: storage: Remove reference counting

The kref used to be needed because sharing of fsg_common among multiple USB
function instances was handled by fsg. Now this is managed by configfs, we
don't need it anymore. So let's eliminate kref from this driver.
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Jaejoong Kim <climbbb.kim@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/function/f_mass_storage.c

@@ -206,7 +206,6 @@
 #include <linux/fcntl.h>
 #include <linux/file.h>
 #include <linux/fs.h>
-#include <linux/kref.h>
 #include <linux/kthread.h>
 #include <linux/sched/signal.h>
 #include <linux/limits.h>
@@ -312,8 +311,6 @@ struct fsg_common {
 	void			*private_data;
 
 	char inquiry_string[INQUIRY_STRING_LEN];
-
-	struct kref		ref;
 };
 
 struct fsg_dev {
@@ -2551,25 +2548,11 @@ static DEVICE_ATTR(file, 0, file_show, file_store);
 
 /****************************** FSG COMMON ******************************/
 
-static void fsg_common_release(struct kref *ref);
-
 static void fsg_lun_release(struct device *dev)
 {
 	/* Nothing needs to be done */
 }
 
-void fsg_common_get(struct fsg_common *common)
-{
-	kref_get(&common->ref);
-}
-EXPORT_SYMBOL_GPL(fsg_common_get);
-
-void fsg_common_put(struct fsg_common *common)
-{
-	kref_put(&common->ref, fsg_common_release);
-}
-EXPORT_SYMBOL_GPL(fsg_common_put);
-
 static struct fsg_common *fsg_common_setup(struct fsg_common *common)
 {
 	if (!common) {
@@ -2582,7 +2565,6 @@ static struct fsg_common *fsg_common_setup(struct fsg_common *common)
 	}
 	init_rwsem(&common->filesem);
 	spin_lock_init(&common->lock);
-	kref_init(&common->ref);
 	init_completion(&common->thread_notifier);
 	init_waitqueue_head(&common->io_wait);
 	init_waitqueue_head(&common->fsg_wait);
@@ -2870,9 +2852,8 @@ void fsg_common_set_inquiry_string(struct fsg_common *common, const char *vn,
 }
 EXPORT_SYMBOL_GPL(fsg_common_set_inquiry_string);
 
-static void fsg_common_release(struct kref *ref)
+static void fsg_common_release(struct fsg_common *common)
 {
-	struct fsg_common *common = container_of(ref, struct fsg_common, ref);
 	int i;
 
 	/* If the thread isn't already dead, tell it to exit now */
@@ -3346,7 +3327,7 @@ static void fsg_free_inst(struct usb_function_instance *fi)
 	struct fsg_opts *opts;
 
 	opts = fsg_opts_from_func_inst(fi);
-	fsg_common_put(opts->common);
+	fsg_common_release(opts->common);
 	kfree(opts);
 }
 
@@ -3370,7 +3351,7 @@ static struct usb_function_instance *fsg_alloc_inst(void)
 	rc = fsg_common_set_num_buffers(opts->common,
 					CONFIG_USB_GADGET_STORAGE_NUM_BUFFERS);
 	if (rc)
-		goto release_opts;
+		goto release_common;
 
 	pr_info(FSG_DRIVER_DESC ", version: " FSG_DRIVER_VERSION "\n");
 
@@ -3393,6 +3374,8 @@ static struct usb_function_instance *fsg_alloc_inst(void)
 
 release_buffers:
 	fsg_common_free_buffers(opts->common);
+release_common:
+	kfree(opts->common);
 release_opts:
 	kfree(opts);
 	return ERR_PTR(rc);

drivers/usb/gadget/function/f_mass_storage.h

@@ -115,10 +115,6 @@ fsg_opts_from_func_inst(const struct usb_function_instance *fi)
 	return container_of(fi, struct fsg_opts, func_inst);
 }
 
-void fsg_common_get(struct fsg_common *common);
-
-void fsg_common_put(struct fsg_common *common);
-
 void fsg_common_set_sysfs(struct fsg_common *common, bool sysfs);
 
 int fsg_common_set_num_buffers(struct fsg_common *common, unsigned int n);