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From: Michal Nazarewicz on 29 Mar 2010 08:10
Mass Storage Function (MSF) used the same descriptors for each
usb_function instance (meaning usb_function::descriptors of different
functions pointed to the same static area (the same was true for
usb_function::hs_descriptors)).

This would leads to problems if MSF were used in several USB
configurations with different interface and/or endpoint numbers.
Descriptors for all configurations would have interface/endpoint
numbers overwritten by the values valid for the last configuration.

This patch adds code that copies the descriptors each time MSF is
added to USB configuration (that is for each usb_function).

Signed-off-by: Michal Nazarewicz <m.nazarewicz(a)samsung.com>
Cc: Kyungmin Park <kyungmin.park(a)samsung.com>
---
> On Mon, Mar 29, 2010 at 12:18:43PM +0200, Michal Nazarewicz wrote:
>> @@ -2946,7 +2948,13 @@ static int __init fsg_bind(struct usb_configuration *c, struct usb_function *f)
>> fsg_fs_bulk_in_desc.bEndpointAddress;
>> fsg_hs_bulk_out_desc.bEndpointAddress =
>> fsg_fs_bulk_out_desc.bEndpointAddress;
>> - f->hs_descriptors = fsg_hs_function;
>> + f->hs_descriptors = usb_copy_descriptors(fsg_hs_function);
>> + /* We don't care if we could not copy the high speed
>> + * descriptor. If we are out of memory we'll stick to
>> + * full speed only. Ie. it is an error that we cannot
>> + * copy hs descriptors but not a fatal one. */
>> + /* if (unlikely(!f->hs_descriptors))
>> + return -ENOMEM; */

On Mon, 29 Mar 2010 12:52:04 +0200, Johannes Weiner <hannes(a)cmpxchg.org> wrote:
> I would much prefer to fail here and handle reloading a module in userspace
> over having a gadget operate on varying speeds, depending on a transient
> situation at module loading time that is not transparent to the user of an
> embedded device in the field for example.

As you wish. Modified patch included.

drivers/usb/gadget/f_mass_storage.c | 28 ++++++++++++++++++++++------
1 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
index f4911c0..1f7ca59 100644
--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -2906,6 +2906,8 @@ static void fsg_unbind(struct usb_configuration *c, struct usb_function *f)

DBG(fsg, "unbind\n");
fsg_common_put(fsg->common);
+ usb_free_descriptors(fsg->function.descriptors);
+ usb_free_descriptors(fsg->function.hs_descriptors);
kfree(fsg);
}

@@ -2946,7 +2948,9 @@ static int __init fsg_bind(struct usb_configuration *c, struct usb_function *f)
fsg_fs_bulk_in_desc.bEndpointAddress;
fsg_hs_bulk_out_desc.bEndpointAddress =
fsg_fs_bulk_out_desc.bEndpointAddress;
- f->hs_descriptors = fsg_hs_function;
+ f->hs_descriptors = usb_copy_descriptors(fsg_hs_function);
+ if (unlikely(!f->hs_descriptors))
+ return -ENOMEM;
}

return 0;
@@ -2978,7 +2982,11 @@ static int fsg_add(struct usb_composite_dev *cdev,

fsg->function.name = FSG_DRIVER_DESC;
fsg->function.strings = fsg_strings_array;
- fsg->function.descriptors = fsg_fs_function;
+ fsg->function.descriptors = usb_copy_descriptors(fsg_fs_function);
+ if (unlikely(!fsg->function.descriptors)) {
+ rc = -ENOMEM;
+ goto error_free_fsg;
+ }
fsg->function.bind = fsg_bind;
fsg->function.unbind = fsg_unbind;
fsg->function.setup = fsg_setup;
@@ -2993,11 +3001,19 @@ static int fsg_add(struct usb_composite_dev *cdev,
* call to usb_add_function() was successful. */

rc = usb_add_function(c, &fsg->function);
+ if (unlikely(rc))
+ goto error_free_all;

- if (likely(rc == 0))
- fsg_common_get(fsg->common);
- else
- kfree(fsg);
+ fsg_common_get(fsg->common);
+ return 0;
+
+error_free_all:
+ usb_free_descriptors(fsg->function.descriptors);
+ /* fsg_bind() might have copied those; or maybe not? who cares
+ * -- free it just in case. */
+ usb_free_descriptors(fsg->function.hs_descriptors);
+error_free_fsg:
+ kfree(fsg);

return rc;
}
--
1.7.0

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Prev: lmb: Add __NOT_KEEP_LMB to put lmb code to .init
Next: [PATCH 8/8] staging: vt6656: tcrc.c: Fixed coding style issues