USB: Gadget: Composite: Added error handling codes to prevent a memory leak case when the configuration's bind function failed
Dear Michal Nazarewicz
I'm very thank you for your comments about this patch. And I think you might mis-understand my mention about this patch. (Becasue i'm not native english speaker)
My point is that,
if the next function(second or third) binding is failed,
all already added functions that successfully added by making instance are useless functions and these "useless function instances" are make "memory leak situation" because the following codes
(by following codes, composite-FW or gadget-FW cannot handle it anymore)
694) list_del(&config->list);
695) config->cdev = NULL;
(original codes of composite.c)
Quoted 2 lines
Also, should this be handled in
usb_gadget_probe_driver()instead? Ie. on error recovery path, shouldusb_gadget_probe_driver()callusb_gadget_remove_driver()?
=> the usb_gadget_remove_driver() cannot handle it because the configuration (that has next function binding failure)
was already separated from "cdev" by the 694 & 695 line of composite.c
Quoted 3 lines
In particular, if I'm not mistaken, for (some?) gadgets with two configurations (like
g_multi), if the second configuration fails, the first one will not get removed, so the memory will still leak, no?
=> you're right , but this your mention case is different with the "memory leak situation" as already mentioned for my patch Because your mention case can be freed later(because first one doesn't separated from "cdev") but my case cannot free it
Best regards,
Yongsul Oh
------- Original Message -------
Sender : Michal Nazarewicz<[email protected]>
Date : 2012-03-15 17:19 (GMT+09:00)
Title : Re: [PATCH] USB: Gadget: Composite: Added error handling codes to prevent a memory leak case when the configuration's bind function failed
Quoted 7 lines · On Thu, 15 Mar 2012 02:23:55 +0100, wrote:
In some usb gadget driver, for example usb gadget serial driver(serial.c),
multifunction compositedriver(multi,c), nokia composite gadget driver(nokia.c), HID composite driver(hid.c), CDC composite driver(cdc2.c).., the configuration's bind function by called the 'usb_add_config()' has multiple bind config functions for each functionality, for example cdc2 configuration bind function -'cdc_do_config()' has two functionality bind config functions -'ecm_bind_config()' & 'acm_bind_config()' in CDC composite driver.
Quoted 8 lines
In each functionality bind config function, new instance for each functionality is
allocated & initialized by 'kzalloc()' ,and finally the new instance is added by 'usb_add_function()'. After 'usb_add_function' state, already created the instance is only handled by its configuration & freed from functionality unbind function.
So, If an error occurred during the second functionality bind config state, for example
an error occurred at 'acm_bind_config()' after succeeding 'ecm_bind_function()', The created instance by 'acm_bind_config()' cannot be freed.
And it makes memory leak situation.
It may be my poor English skills, but this is very hard to read.
Also, should this be handled in usb_gadget_probe_driver() instead? Ie. on error recovery path, should usb_gadget_probe_driver() call usb_gadget_remove_driver()?
In particular, if I'm not mistaken, for (some?) gadgets with two configurations (like g_multi), if the second configuration fails, the first one will not get removed, so the memory will still leak, no?
Quoted 28 lines
Signed-off-by [email protected]--- drivers/usb/gadget/composite.c | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-)drivers/usb/gadget/composite.c +13
-0@@ -737,6 +737,19 @@ int usb_add_config(struct usb_composite_dev *cdev, status =bind (config);if (status <0 ) { +while (!list_empty (&config->functions)) { +struct usb_function *f; + + f =list_first_entry (&config->functions, + struct usb_function, list); +list_del (&f->list); +if (f->unbind) { +DBG (cdev,"unbind function '%s'/%p\n" , + f->name, f); + f->unbind (config, f); +/* may free memory for "f" */ + } + }list_del (&config->list); config->cdev =NULL ; }else {
Signature · 56 lines
Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michał “mina86” Nazarewicz (o o) ooo +------------------ooO--(_)--Ooo-- Oh, Yong-Sul Engineer Mobile S/W Platform Lab. Telecommunication R&D Center Telecommunication Network Business SAMSUNG ELECTRONICS CO.,LTD Tel : +82-31-279-0284 Mobile : +82-10-9530-0284 Fax : +82-31-279-5521 E-mail : [email protected] Copyrightⓒ 2005 Samsung Electronics Co., Ltd. All rights reserved | Confidential The information contained in this message is confidential and may be legally privileged. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, dissemination, or reproduction is strictly prohibited and may be unlawful. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message. Oh, Yong-Sul Engineer Mobile S/W Platform Lab. Telecommunication R&D Center Telecommunication Network Business SAMSUNG ELECTRONICS CO.,LTD Tel : +82-31-279-0284 Mobile : +82-10-9530-0284 Fax : +82-31-279-5521 E-mail : [email protected] Copyrightⓒ 2005 Samsung Electronics Co., Ltd. All rights reserved | Confidential The information contained in this message is confidential and may be legally privileged. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, dissemination, or reproduction is strictly prohibited and may be unlawful. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message. ���{.n�+�������+%�����ݶ��w��{.n�+����{��G�����{ay� ʇڙ�,j��f���h��������z_�(�階�ݢj"���m������G������?����&���~��iO��z��v�^�m���� ������?�I�