[PATCH] USB: file-storage gadget: Add reference count for children
This patch (as601) adds a proper reference count to the file-storage
gadget's main data structure, to keep track of references held by child
devices (LUNs in this case). Before this, the driver would wait for
each child to be released before unbinding.
While there's nothing really wrong with that (you can't create a hang by
doing "rmmod g_file_storage </sys/.../lun0/ro" since the open file will
prevent rmmod from running), the code might as well follow the standard
procedures. Besides, this shrinks the size of the structure by a few
words... :-)
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index ea09aaa..f6f0b2a 100644
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -224,6 +224,7 @@
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
+#include <linux/kref.h>
#include <linux/kthread.h>
#include <linux/limits.h>
#include <linux/list.h>
@@ -631,6 +632,9 @@
/* filesem protects: backing files in use */
struct rw_semaphore filesem;
+ /* reference counting: wait until all LUNs are released */
+ struct kref ref;
+
struct usb_ep *ep0; // Handy copy of gadget->ep0
struct usb_request *ep0req; // For control responses
volatile unsigned int ep0_req_tag;
@@ -694,7 +698,6 @@
unsigned int nluns;
struct lun *luns;
struct lun *curlun;
- struct completion lun_released;
};
typedef void (*fsg_routine_t)(struct fsg_dev *);
@@ -3642,11 +3645,19 @@
/*-------------------------------------------------------------------------*/
+static void fsg_release(struct kref *ref)
+{
+ struct fsg_dev *fsg = container_of(ref, struct fsg_dev, ref);
+
+ kfree(fsg->luns);
+ kfree(fsg);
+}
+
static void lun_release(struct device *dev)
{
struct fsg_dev *fsg = (struct fsg_dev *) dev_get_drvdata(dev);
- complete(&fsg->lun_released);
+ kref_put(&fsg->ref, fsg_release);
}
static void fsg_unbind(struct usb_gadget *gadget)
@@ -3660,14 +3671,12 @@
clear_bit(REGISTERED, &fsg->atomic_bitflags);
/* Unregister the sysfs attribute files and the LUNs */
- init_completion(&fsg->lun_released);
for (i = 0; i < fsg->nluns; ++i) {
curlun = &fsg->luns[i];
if (curlun->registered) {
device_remove_file(&curlun->dev, &dev_attr_ro);
device_remove_file(&curlun->dev, &dev_attr_file);
device_unregister(&curlun->dev);
- wait_for_completion(&fsg->lun_released);
curlun->registered = 0;
}
}
@@ -3846,6 +3855,7 @@
curlun->dev.release = lun_release;
device_create_file(&curlun->dev, &dev_attr_ro);
device_create_file(&curlun->dev, &dev_attr_file);
+ kref_get(&fsg->ref);
}
if (file[i] && *file[i]) {
@@ -4061,6 +4071,7 @@
return -ENOMEM;
spin_lock_init(&fsg->lock);
init_rwsem(&fsg->filesem);
+ kref_init(&fsg->ref);
init_waitqueue_head(&fsg->thread_wqh);
init_completion(&fsg->thread_notifier);
@@ -4069,13 +4080,6 @@
}
-static void fsg_free(struct fsg_dev *fsg)
-{
- kfree(fsg->luns);
- kfree(fsg);
-}
-
-
static int __init fsg_init(void)
{
int rc;
@@ -4085,7 +4089,7 @@
return rc;
fsg = the_fsg;
if ((rc = usb_gadget_register_driver(&fsg_driver)) != 0)
- fsg_free(fsg);
+ kref_put(&fsg->ref, fsg_release);
return rc;
}
module_init(fsg_init);
@@ -4103,6 +4107,6 @@
wait_for_completion(&fsg->thread_notifier);
close_all_backing_files(fsg);
- fsg_free(fsg);
+ kref_put(&fsg->ref, fsg_release);
}
module_exit(fsg_cleanup);