From: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
To: Ajay Kaher <ajay.kaher@samsung.com>
Cc: Alan Stern <stern@rowland.harvard.edu>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
AMAN DEEP <aman.deep@samsung.com>,
HEMANSHU SRIVASTAVA <hemanshu.s@samsung.com>
Subject: Re: [PATCH v4] USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously
Date: Thu, 23 Mar 2017 08:18:50 +0100 [thread overview]
Message-ID: <20170323071850.GA13002@kroah.com> (raw)
In-Reply-To: <20170317105637epcms5p2d296f449d5c5712718d6efab69948985@epcms5p2>
On Fri, Mar 17, 2017 at 10:56:37AM +0000, Ajay Kaher wrote:
> There is race condition when two USB class drivers try to call
> init_usb_class at the same time and leads to crash.
> code path: probe->usb_register_dev->init_usb_class
>
> To solve this, mutex locking has been added in init_usb_class() and
> destroy_usb_class().
>
> As pointed by Alan, removed "if (usb_class)" test from destroy_usb_class()
> because usb_class can never be NULL there.
>
> Signed-off-by: Ajay Kaher <ajay.kaher@samsung.com>
> Acked-by: Alan Stern <stern@rowland.harvard.edu>
> ---
> drivers/usb/core/file.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/core/file.c b/drivers/usb/core/file.c
> index 822ced9..422ce7b 100644
> --- a/drivers/usb/core/file.c
> +++ b/drivers/usb/core/file.c
> @@ -27,6 +27,7 @@
> #define MAX_USB_MINORS 256
> static const struct file_operations *usb_minors[MAX_USB_MINORS];
> static DECLARE_RWSEM(minor_rwsem);
> +static DEFINE_MUTEX(init_usb_class_mutex);
>
> static int usb_open(struct inode *inode, struct file *file)
> {
> @@ -109,8 +110,9 @@ static void release_usb_class(struct kref *kref)
>
> static void destroy_usb_class(void)
> {
> - if (usb_class)
> - kref_put(&usb_class->kref, release_usb_class);
> + mutex_lock(&init_usb_class_mutex);
> + kref_put(&usb_class->kref, release_usb_class);
> + mutex_unlock(&init_usb_class_mutex);
> }
>
> int usb_major_init(void)
> @@ -171,7 +173,10 @@ int usb_register_dev(struct usb_interface *intf,
> if (intf->minor >= 0)
> return -EADDRINUSE;
>
> + mutex_lock(&init_usb_class_mutex);
> retval = init_usb_class();
> + mutex_unlock(&init_usb_class_mutex);
> +
> if (retval)
> return retval;
>
I get the following errors when trying to apply this patch:
Applying: USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously
.git/rebase-apply/patch:13: trailing whitespace.
static DEFINE_MUTEX(init_usb_class_mutex);
.git/rebase-apply/patch:23: trailing whitespace.
mutex_lock(&init_usb_class_mutex);
.git/rebase-apply/patch:24: trailing whitespace.
kref_put(&usb_class->kref, release_usb_class);
.git/rebase-apply/patch:25: trailing whitespace.
mutex_unlock(&init_usb_class_mutex);
.git/rebase-apply/patch:33: trailing whitespace.
mutex_lock(&init_usb_class_mutex);
error: patch failed: drivers/usb/core/file.c:27
error: drivers/usb/core/file.c: patch does not apply
Patch failed at 0001 USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously
Are you sure you made this in the correct format? Seems that the patch
has dos line-ends :(
Please fix up and resend.
thanks,
greg k-h
next prev parent reply other threads:[~2017-03-23 7:37 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20170220192040epcas3p37ded8ece49ed9385df80d3b813a953bc@epcas3p3.samsung.com>
2017-02-22 12:57 ` Re: Subject: [PATCH v3] USB:Core: BugFix: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously Ajay Kaher
[not found] ` <CGME20170220192040epcas3p37ded8ece49ed9385df80d3b813a953bc@epcms5p3>
2017-03-01 11:12 ` FW: " Ajay Kaher
2017-03-01 15:15 ` Alan Stern
[not found] ` <CGME20170301151552epcas5p3ecf8f7dc55323b2ceaff8c8a9b9644c4@epcms5p1>
2017-03-02 7:49 ` FW: RE: " Ajay Kaher
[not found] ` <CGME20170301151552epcas5p3ecf8f7dc55323b2ceaff8c8a9b9644c4@epcms5p2>
2017-03-03 14:49 ` FW: " Ajay Kaher
2017-03-03 16:53 ` Alan Stern
[not found] ` <CGME20170303165352epcas5p2c408a284100b5053daf458a4ad4d9337@epcms5p7>
2017-03-07 4:35 ` Subject: [PATCH v4] " Ajay Kaher
2017-03-07 15:00 ` Alan Stern
[not found] ` <CGME20170307150103epcas2p348320fdfbb176978d084d8f2b7b9a049@epcms5p7>
2017-03-09 11:34 ` Ajay Kaher
2017-03-09 12:10 ` gregkh
[not found] ` <CGME20170307150103epcas2p348320fdfbb176978d084d8f2b7b9a049@epcms5p2>
2017-03-17 10:56 ` [PATCH v4] USB: " Ajay Kaher
2017-03-23 7:18 ` gregkh [this message]
2017-03-21 14:49 ` FW: " Ajay Kaher
2017-03-08 18:05 ` Subject: [PATCH v4] USB:Core: BugFix: " gregkh
[not found] <CGME20170328121013epcas5p493f1509064350349fbcdb655793d8d4e@epcas5p4.samsung.com>
2017-03-28 12:09 ` [PATCH v4] USB: " Ajay Kaher
2017-03-29 9:56 ` Greg KH
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