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Groups > linux.kernel > #1603212 > unrolled thread
| Started by | Ajay Kaher <ajay.kaher@samsung.com> |
|---|---|
| First post | 2017-03-17 12:20 +0100 |
| Last post | 2017-03-23 08:40 +0100 |
| Articles | 3 — 2 participants |
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Re: [PATCH v4] USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously Ajay Kaher <ajay.kaher@samsung.com> - 2017-03-17 12:20 +0100
FW: Re: [PATCH v4] USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously Ajay Kaher <ajay.kaher@samsung.com> - 2017-03-22 06:20 +0100
Re: [PATCH v4] USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org> - 2017-03-23 08:40 +0100
| From | Ajay Kaher <ajay.kaher@samsung.com> |
|---|---|
| Date | 2017-03-17 12:20 +0100 |
| Subject | Re: [PATCH v4] USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously |
| Message-ID | <tlY5k-5AZ-25@gated-at.bofh.it> |
[Multipart message — attachments visible in raw view] — view raw
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;
--
1.7.9.5
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| From | Ajay Kaher <ajay.kaher@samsung.com> |
|---|---|
| Date | 2017-03-22 06:20 +0100 |
| Message-ID | <tnGQF-5L3-5@gated-at.bofh.it> |
| In reply to | #1603212 |
[Multipart message — attachments visible in raw view] — view raw
Greg, hope you had not faced any issue (tab converted to spaces) with this patch.
In case still facing any issue please let me know.
> 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;
--
1.7.9.5
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| From | "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org> |
|---|---|
| Date | 2017-03-23 08:40 +0100 |
| Message-ID | <to5vJ-7s8-37@gated-at.bofh.it> |
| In reply to | #1603212 |
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
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