[PATCH 3.16.y-ckt 032/118] usb: f_mass_storage: limit number of reported LUNs

[Luis Henriques]

3.16.7-ckt16 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Michal Nazarewicz <mina86 at mina86.com>

commit 8515bac01a983d277148e4fcc5f235bf603de577 upstream.

Mass storage function created via configfs always reports eight LUNs
to the hosts even if only one LUN has been configured.  Adjust the
number when the USB function is allocated based on LUNs that user
has created.

Tested-by: Gregory CLEMENT <gregory.clement at free-electrons.com>
Signed-off-by: Michal Nazarewicz <mina86 at mina86.com>
Signed-off-by: Felipe Balbi <balbi at ti.com>
[ luis: backported to 3.16:
  - file rename: drivers/usb/gadget/function/f_mass_storage.c ->
    drivers/usb/gadget/f_mass_storage.c ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/usb/gadget/f_mass_storage.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
index b96393908860..53f4d4a868b5 100644
--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -2819,7 +2819,7 @@ int fsg_common_set_nluns(struct fsg_common *common, int nluns)
 		return -EINVAL;
 	}
 
-	curlun = kcalloc(nluns, sizeof(*curlun), GFP_KERNEL);
+	curlun = kcalloc(FSG_MAX_LUNS, sizeof(*curlun), GFP_KERNEL);
 	if (unlikely(!curlun))
 		return -ENOMEM;
 
@@ -2829,8 +2829,6 @@ int fsg_common_set_nluns(struct fsg_common *common, int nluns)
 	common->luns = curlun;
 	common->nluns = nluns;
 
-	pr_info("Number of LUNs=%d\n", common->nluns);
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(fsg_common_set_nluns);
@@ -3604,14 +3602,26 @@ static struct usb_function *fsg_alloc(struct usb_function_instance *fi)
 	struct fsg_opts *opts = fsg_opts_from_func_inst(fi);
 	struct fsg_common *common = opts->common;
 	struct fsg_dev *fsg;
+	unsigned nluns, i;
 
 	fsg = kzalloc(sizeof(*fsg), GFP_KERNEL);
 	if (unlikely(!fsg))
 		return ERR_PTR(-ENOMEM);
 
 	mutex_lock(&opts->lock);
+	if (!opts->refcnt) {
+		for (nluns = i = 0; i < FSG_MAX_LUNS; ++i)
+			if (common->luns[i])
+				nluns = i + 1;
+		if (!nluns)
+			pr_warn("No LUNS defined, continuing anyway\n");
+		else
+			common->nluns = nluns;
+		pr_info("Number of LUNs=%u\n", common->nluns);
+	}
 	opts->refcnt++;
 	mutex_unlock(&opts->lock);
+
 	fsg->function.name	= FSG_DRIVER_DESC;
 	fsg->function.bind	= fsg_bind;
 	fsg->function.unbind	= fsg_unbind;