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 b4ec76a3e37..5a0f5708c09 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, "controller '%s' not recognized\n",
+                                gadget->name);
+                        mod_data.release = 0x0399;
+                }
+        }
+
+
+        /* Some peripheral controllers are known not to be able to
+         * halt bulk endpoints correctly.  If one of them is present,
+         * disable stalls.
+         */
+        if (gadget_is_sh(fsg->gadget) || gadget_is_at91(fsg->gadget))
+                mod_data.can_stall = 0;
+
+
+        kref_init(&common->ref);
+        return common;
+
+
+error_luns:
+        common->nluns = i + 1;
+error_release:
+        /* Call fsg_common_release() directly, ref is not initialised */
+        fsg_common_release(&common->ref);
+        return ERR_PTR(rc);
+}
+
+
+static void fsg_common_release(struct kref *ref)
+{
+        struct fsg_common *common =
+                container_of(ref, struct fsg_common, ref);
+        unsigned i = common->nluns;
+        struct fsg_lun *lun = common->luns;
+
+        /* Beware tempting for -> do-while optimization: when in error
+         * recovery nluns may be zero. */
+
+        for (; i; --i, ++lun) {
+                device_remove_file(&lun->dev, &dev_attr_ro);
+                device_remove_file(&lun->dev, &dev_attr_file);
+                fsg_lun_close(lun);
+                device_unregister(&lun->dev);
+        }
+
+        kfree(common->luns);
+        if (common->free_storage_on_release)
+                kfree(common);
+}
+
+
+/*-------------------------------------------------------------------------*/
+
+
 static void /* __init_or_exit */ fsg_unbind(struct usb_gadget *gadget)
 {
         struct fsg_dev          *fsg = get_gadget_data(gadget);
-        int                     i;
-        struct fsg_lun          *curlun;
         struct usb_request      *req = fsg->ep0req;
 
         DBG(fsg, "unbind\n");
         clear_bit(REGISTERED, &fsg->atomic_bitflags);
 
-        /* Unregister the sysfs attribute files and the LUNs */
-        for (i = 0; i < fsg->common->nluns; ++i) {
-                curlun = &fsg->common->luns[i];
-                if (curlun->registered) {
-                        device_remove_file(&curlun->dev, &dev_attr_ro);
-                        device_remove_file(&curlun->dev, &dev_attr_file);
-                        fsg_lun_close(curlun);
-                        device_unregister(&curlun->dev);
-                        curlun->registered = 0;
-                }
-        }
-
         /* If the thread isn't already dead, tell it to exit now */
         if (fsg->state != FSG_STATE_TERMINATED) {
                 raise_exception(fsg, FSG_STATE_EXIT);
@@ -2814,43 +2967,15 @@ static void /* __init_or_exit */ fsg_unbind(struct usb_gadget *gadget)
                 usb_ep_free_request(fsg->ep0, req);
         }
 
+        fsg_common_put(fsg->common);
+        kfree(fsg);
         set_gadget_data(gadget, NULL);
 }
 
 
-static int __init check_parameters(struct fsg_dev *fsg)
-{
-        int     gcnum;
-
-        /* Some peripheral controllers are known not to be able to
-         * halt bulk endpoints correctly.  If one of them is present,
-         * disable stalls.
-         */
-        if (gadget_is_sh(fsg->gadget) || gadget_is_at91(fsg->gadget))
-                mod_data.can_stall = 0;
-
-        if (mod_data.release == 0xffff) {       // Parameter wasn't set
-                /* The sa1100 controller is not supported */
-                if (gadget_is_sa1100(fsg->gadget))
-                        gcnum = -1;
-                else
-                        gcnum = usb_gadget_controller_number(fsg->gadget);
-                if (gcnum >= 0)
-                        mod_data.release = 0x0300 + gcnum;
-                else {
-                        WARNING(fsg, "controller '%s' not recognized\n",
-                                fsg->gadget->name);
-                        mod_data.release = 0x0399;
-                }
-        }
-
-        return 0;
-}
-
-
 static int __init fsg_bind(struct usb_gadget *gadget)
 {
-        struct fsg_dev          *fsg = the_fsg;
+        struct fsg_dev          *fsg;
         int                     rc;
         int                     i;
         struct fsg_lun          *curlun;
@@ -2858,15 +2983,27 @@ static int __init fsg_bind(struct usb_gadget *gadget)
         struct usb_request      *req;
         char                    *pathbuf, *p;
 
+        /* Allocate */
+        fsg = kzalloc(sizeof *fsg, GFP_KERNEL);
+        if (!fsg)
+                return -ENOMEM;
+
+        /* Initialise common */
+        fsg->common = fsg_common_init(0, gadget);
+        if (IS_ERR(fsg->common))
+                return PTR_ERR(fsg->common);
+
+        /* Basic parameters */
         fsg->gadget = gadget;
         set_gadget_data(gadget, fsg);
         fsg->ep0 = gadget->ep0;
         fsg->ep0->driver_data = fsg;
 
-        if ((rc = check_parameters(fsg)) != 0)
-                goto out;
+        spin_lock_init(&fsg->lock);
+        init_completion(&fsg->thread_notifier);
 
-        if (mod_data.removable) {       // Enable the store_xxx attributes
+        /* Enable the store_xxx attributes */
+        if (mod_data.removable) {
                 dev_attr_file.attr.mode = 0644;
                 dev_attr_file.store = fsg_store_file;
                 if (!mod_data.cdrom) {
@@ -2875,62 +3012,6 @@ static int __init fsg_bind(struct usb_gadget *gadget)
                 }
         }
 
-        /* Find out how many LUNs there should be */
-        i = mod_data.nluns;
-        if (i == 0)
-                i = max(mod_data.num_filenames, 1u);
-        if (i > FSG_MAX_LUNS) {
-                ERROR(fsg, "invalid number of LUNs: %d\n", i);
-                rc = -EINVAL;
-                goto out;
-        }
-
-        /* Create the LUNs, open their backing files, and register the
-         * LUN devices in sysfs. */
-        fsg->common->luns = kzalloc(i * sizeof(struct fsg_lun), GFP_KERNEL);
-        if (!fsg->common->luns) {
-                rc = -ENOMEM;
-                goto out;
-        }
-        fsg->common->nluns = i;
-
-        for (i = 0; i < fsg->common->nluns; ++i) {
-                curlun = &fsg->common->luns[i];
-                curlun->cdrom = !!mod_data.cdrom;
-                curlun->ro = mod_data.cdrom || mod_data.ro[i];
-                curlun->initially_ro = curlun->ro;
-                curlun->removable = mod_data.removable;
-                curlun->dev.release = lun_release;
-                curlun->dev.parent = &gadget->dev;
-                curlun->dev.driver = &fsg_driver.driver;
-                dev_set_drvdata(&curlun->dev, &fsg->common->filesem);
-                dev_set_name(&curlun->dev,"%s-lun%d",
-                             dev_name(&gadget->dev), i);
-
-                if ((rc = device_register(&curlun->dev)) != 0) {
-                        INFO(fsg, "failed to register LUN%d: %d\n", i, rc);
-                        goto out;
-                }
-                if ((rc = device_create_file(&curlun->dev,
-                                        &dev_attr_ro)) != 0 ||
-                                (rc = device_create_file(&curlun->dev,
-                                        &dev_attr_file)) != 0) {
-                        device_unregister(&curlun->dev);
-                        goto out;
-                }
-                curlun->registered = 1;
-
-                if (mod_data.file[i] && *mod_data.file[i]) {
-                        if ((rc = fsg_lun_open(curlun,
-                                        mod_data.file[i])) != 0)
-                                goto out;
-                } else if (!mod_data.removable) {
-                        ERROR(fsg, "no file given for LUN%d\n", i);
-                        rc = -EINVAL;
-                        goto out;
-                }
-        }
-
         /* Find all the endpoints we will use */
         usb_ep_autoconfig_reset(gadget);
         ep = usb_ep_autoconfig(gadget, &fsg_fs_bulk_in_desc);
@@ -3028,6 +3109,8 @@ static int __init fsg_bind(struct usb_gadget *gadget)
 
         /* Tell the thread to start working */
         wake_up_process(fsg->thread_task);
+
+        the_fsg = fsg;
         return 0;
 
 autoconf_fail:
@@ -3066,64 +3149,18 @@ static struct usb_gadget_driver		fsg_driver = {
 };
 
 
-static int __init fsg_alloc(void)
-{
-        struct fsg_dev          *fsg;
-        struct fsg_buffhd       *bh;
-        unsigned                i;
-
-        fsg = kzalloc(sizeof *fsg, GFP_KERNEL);
-        if (!fsg)
-                return -ENOMEM;
-
-        fsg->common = kzalloc(sizeof *fsg->common, GFP_KERNEL);
-        if (!fsg->common) {
-                kfree(fsg);
-                return -ENOMEM;
-        }
-
-        bh = fsg->common->buffhds;
-        i = FSG_NUM_BUFFERS - 1;
-        do {
-                bh->next = bh + 1;
-        } while (++bh, --i);
-        bh->next = fsg->common->buffhds;
-
-        spin_lock_init(&fsg->lock);
-        init_rwsem(&fsg->common->filesem);
-        init_completion(&fsg->thread_notifier);
-
-        the_fsg = fsg;
-        return 0;
-}
-
-
 static int __init fsg_init(void)
 {
-        int             rc;
-        struct fsg_dev  *fsg;
-
-        if ((rc = fsg_alloc()) != 0)
-                return rc;
-        fsg = the_fsg;
-        if ((rc = usb_gadget_register_driver(&fsg_driver)) != 0)
-                fsg_release(fsg);
-        return rc;
+        return usb_gadget_register_driver(&fsg_driver);
 }
 module_init(fsg_init);
 
 
 static void __exit fsg_cleanup(void)
 {
-        struct fsg_dev  *fsg = the_fsg;
-
         /* Unregister the driver iff the thread hasn't already done so */
-        if (test_and_clear_bit(REGISTERED, &fsg->atomic_bitflags))
+        if (the_fsg &&
+            test_and_clear_bit(REGISTERED, &the_fsg->atomic_bitflags))
                 usb_gadget_unregister_driver(&fsg_driver);
-
-        /* Wait for the thread to finish up */
-        wait_for_completion(&fsg->thread_notifier);
-
-        fsg_release(fsg);
 }
 module_exit(fsg_cleanup);