[PATCH v2 3/4] usb: gadget: mass_storage: Ensure that lun ids are contiguous

[Krzysztof Opasiak]

Signed-off-by: Krzysztof Opasiak <k.opas...@samsung.com>
---
 drivers/usb/gadget/function/f_mass_storage.c |   35 +++++++++++++++++++++++---
 1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/function/f_mass_storage.c 
b/drivers/usb/gadget/function/f_mass_storage.c
index 095b618..9d9fafb 100644
--- a/drivers/usb/gadget/function/f_mass_storage.c
+++ b/drivers/usb/gadget/function/f_mass_storage.c
@@ -3355,6 +3355,12 @@ static struct config_group *fsg_lun_make(struct 
config_group *group,
                goto out;
        }
 
+       if (!fsg_opts->common->luns[num - 1]) {
+               ret = -EINVAL;
+               pr_err("LUN ids should be contignous\n");
+               goto out;
+       }
+
        opts = kzalloc(sizeof(*opts), GFP_KERNEL);
        if (!opts) {
                ret = -ENOMEM;
@@ -3364,12 +3370,17 @@ static struct config_group *fsg_lun_make(struct 
config_group *group,
        memset(&config, 0, sizeof(config));
        config.removable = true;
 
+       /* ensure that lun ids are contiguous */
+       ret = configfs_depend_item_unlocked(&(fsg_opts->lun_opts
+                                             [num - 1]->group.cg_item));
+       if (ret)
+               goto err_free_opts;
+
        ret = fsg_common_create_lun(fsg_opts->common, &config, num, name,
                                    (const char **)&group->cg_item.ci_name);
-       if (ret) {
-               kfree(opts);
-               goto out;
-       }
+       if (ret)
+               goto err_undepend_item;
+
        opts->lun = fsg_opts->common->luns[num];
        opts->lun_id = num;
        BUG_ON(fsg_opts->lun_opts[num]);
@@ -3382,6 +3393,16 @@ static struct config_group *fsg_lun_make(struct 
config_group *group,
 out:
        mutex_unlock(&fsg_opts->lock);
        return ERR_PTR(ret);
+
+err_undepend_item:
+       configfs_undepend_item_unlocked(&(fsg_opts->lun_opts
+                                         [num - 1]->group.cg_item));
+err_free_opts:
+       kfree(opts);
+
+       mutex_unlock(&fsg_opts->lock);
+       return ERR_PTR(ret);
+
 }
 
 static void fsg_lun_drop(struct config_group *group, struct config_item *item)
@@ -3400,10 +3421,16 @@ static void fsg_lun_drop(struct config_group *group, 
struct config_item *item)
                unregister_gadget_item(gadget);
        }
 
+
+       /* Allow to remove next one */
+       configfs_undepend_item_unlocked(&(fsg_opts->lun_opts
+                                         [lun_opts->lun_id - 
1]->group.cg_item));
+
        fsg_common_remove_lun(lun_opts->lun, fsg_opts->common->sysfs);
        fsg_opts->common->luns[lun_opts->lun_id] = NULL;
        fsg_opts->lun_opts[lun_opts->lun_id] = NULL;
        lun_opts->lun_id = 0;
+
        mutex_unlock(&fsg_opts->lock);
 
        config_item_put(item);
-- 
1.7.9.5

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