USB: g_mass_storage: fsg_common_init() created

Moved code initialising fsg_common structure to fsg_common_init()
function which is called from fsg_bind().  Moreover, changed
reference counting mechanism: fsg_common has a reference counter
which counts how many fsg_dev structures uses it.  When this
reaches zero fsg_common_release() is run which unregisters
LUN devices and frees memory.

fsg_common_init() takes pointer to fsg_common structure as an
argument.  If it is NULL function allocates storage otherwise
uses pointed to memory (handy if fsg_common is a field of another
structure or a static variable).

fsg_common_release() will free storage only if
free_storage_on_release is set -- it is initialised by
fsg_common_init(): set if allocation was done, unset
otherwise (one may overwrite it of course).

Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 199 insertions, 162 deletions

diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
index b4ec76a3e37d..5a0f5708c094 100644
--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -323,6 +323,8 @@ MODULE_PARM_DESC(cdrom, "true to emulate cdrom instead of disk");
 
 /* Data shared by all the FSG instances. */
 struct fsg_common {
+        struct usb_gadget       *gadget;
+
         /* filesem protects: backing files in use */
         struct rw_semaphore     filesem;
 
@@ -337,6 +339,10 @@ struct fsg_common {
         unsigned int            lun;
         struct fsg_lun          *luns;
         struct fsg_lun          *curlun;
+
+        unsigned int            free_storage_on_release:1;
+
+        struct kref             ref;
 };
 
 
@@ -347,9 +353,6 @@ struct fsg_dev {
         spinlock_t              lock;
         struct usb_gadget       *gadget;
 
-        /* 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
         unsigned int            ep0_req_tag;
@@ -2757,7 +2760,7 @@ static int fsg_main_thread(void *fsg_)
 }
 
 
-/*-------------------------------------------------------------------------*/
+/*************************** DEVICE ATTRIBUTES ***************************/
 
 
 /* The write permissions and store_xxx pointers are set in fsg_bind() */
@@ -2765,40 +2768,190 @@ static DEVICE_ATTR(ro, 0444, fsg_show_ro, NULL);
 static DEVICE_ATTR(file, 0444, fsg_show_file, NULL);
 
 
-/*-------------------------------------------------------------------------*/
+/****************************** FSG COMMON ******************************/
+
+static void fsg_common_release(struct kref *ref);
 
-static void fsg_release(struct fsg_dev *fsg)
+static void fsg_lun_release(struct device *dev)
 {
-        kfree(fsg->common->luns);
-        kfree(fsg);
+        /* Nothing needs to be done */
 }
 
-static void lun_release(struct device *dev)
+static inline void fsg_common_get(struct fsg_common *common)
 {
+        kref_get(&common->ref);
 }
 
+static inline void fsg_common_put(struct fsg_common *common)
+{
+        kref_put(&common->ref, fsg_common_release);
+}
+
+
+static struct fsg_common *fsg_common_init(struct fsg_common *common,
+                                          struct usb_gadget *gadget)
+{
+        struct fsg_buffhd *bh;
+        struct fsg_lun *curlun;
+        int nluns, i, rc;
+
+        /* Find out how many LUNs there should be */
+        nluns = mod_data.nluns;
+        if (nluns == 0)
+                nluns = max(mod_data.num_filenames, 1u);
+        if (nluns < 1 || nluns > FSG_MAX_LUNS) {
+                dev_err(&gadget->dev, "invalid number of LUNs: %u\n", nluns);
+                return ERR_PTR(-EINVAL);
+        }
+
+        /* Allocate? */
+        if (!common) {
+                common = kzalloc(sizeof *common, GFP_KERNEL);
+                if (!common)
+                        return ERR_PTR(-ENOMEM);
+                common->free_storage_on_release = 1;
+        } else {
+                memset(common, 0, sizeof common);
+                common->free_storage_on_release = 0;
+        }
+        common->gadget = gadget;
+
+        /* Create the LUNs, open their backing files, and register the
+         * LUN devices in sysfs. */
+        curlun = kzalloc(nluns * sizeof *curlun, GFP_KERNEL);
+        if (!curlun) {
+                kfree(common);
+                return ERR_PTR(-ENOMEM);
+        }
+        common->luns = curlun;
+
+        init_rwsem(&common->filesem);
+
+        for (i = 0; i < nluns; ++i, ++curlun) {
+                curlun->cdrom = !!mod_data.cdrom;
+                curlun->ro = mod_data.cdrom || mod_data.ro[i];
+                curlun->removable = mod_data.removable;
+                curlun->dev.release = fsg_lun_release;
+                curlun->dev.parent = &gadget->dev;
+                curlun->dev.driver = &fsg_driver.driver;
+                dev_set_drvdata(&curlun->dev, &common->filesem);
+                dev_set_name(&curlun->dev,"%s-lun%d",
+                             dev_name(&gadget->dev), i);
+
+                rc = device_register(&curlun->dev);
+                if (rc) {
+                        INFO(common, "failed to register LUN%d: %d\n", i, rc);
+                        common->nluns = i;
+                        goto error_release;
+                }
+
+                rc = device_create_file(&curlun->dev, &dev_attr_ro);
+                if (rc)
+                        goto error_luns;
+                rc = device_create_file(&curlun->dev, &dev_attr_file);
+                if (rc)
+                        goto error_luns;
+
+                if (mod_data.file[i] && *mod_data.file[i]) {
+                        rc = fsg_lun_open(curlun, mod_data.file[i]);
+                        if (rc)
+                                goto error_luns;
+                } else if (!mod_data.removable) {
+                        ERROR(common, "no file given for LUN%d\n", i);
+                        rc = -EINVAL;
+                        goto error_luns;
+                }
+        }
+        common->nluns = nluns;
+
+
+        /* Data buffers cyclic list */
+        /* Buffers in buffhds are static -- no need for additional
+         * allocation. */
+        bh = common->buffhds;
+        i = FSG_NUM_BUFFERS - 1;
+        do {
+                bh->next = bh + 1;
+        } while (++bh, --i);
+        bh->next = common->buffhds;
+
+
+        /* Release */
+        if (mod_data.release == 0xffff) {       // Parameter wasn't set
+                int     gcnum;
+
+                /* The sa1100 controller is not supported */
+                if (gadget_is_sa1100(gadget))
+                        gcnum = -1;
+                else
+                        gcnum = usb_gadget_controller_number(gadget);
+                if (gcnum >= 0)
+                        mod_data.release = 0x0300 + gcnum;
+                else {
+                        WARNING(common, "controller '%s' not recognized\n",
+                                gadget->name);
+                        WARNING(common, "