[3.16.y-ckt stable] Patch "usb: f_mass_storage: limit number of reported LUNs" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    usb: f_mass_storage: limit number of reported LUNs

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt16.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From be30468aaf6ea7ca81d657cf22f530e108727735 Mon Sep 17 00:00:00 2001
From: Michal Nazarewicz <mina86 at mina86.com>
Date: Fri, 19 Jun 2015 23:56:34 +0200
Subject: usb: f_mass_storage: limit number of reported LUNs

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;