Re: [PATCH v4] USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously
On Tue, Mar 28, 2017 at 08:09:32AM -0400, Ajay Kaher wrote: > Greg, sending patch again using git send-email, please apply. > Let me know if still any issue. Note, please put comments like this below the --- line so I don't have to manually edit the file by hand. I've now queued this up, thanks. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH v4] USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously
Greg, sending patch again using git send-email, please apply. Let me know if still any issue. 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 KaherAcked-by: Alan Stern --- 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(_class->kref, release_usb_class); + mutex_lock(_usb_class_mutex); + kref_put(_class->kref, release_usb_class); + mutex_unlock(_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(_usb_class_mutex); retval = init_usb_class(); + mutex_unlock(_usb_class_mutex); + if (retval) return retval; -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v4] USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously
On Fri, Mar 17, 2017 at 10:56:37AM +, 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> Acked-by: Alan Stern > --- > 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(_class->kref, release_usb_class); > + mutex_lock(_usb_class_mutex); > + kref_put(_class->kref, release_usb_class); > + mutex_unlock(_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(_usb_class_mutex); > retval = init_usb_class(); > + mutex_unlock(_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(_usb_class_mutex); .git/rebase-apply/patch:24: trailing whitespace. kref_put(_class->kref, release_usb_class); .git/rebase-apply/patch:25: trailing whitespace. mutex_unlock(_usb_class_mutex); .git/rebase-apply/patch:33: trailing whitespace. mutex_lock(_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 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
FW: Re: [PATCH v4] USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously
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 KaherAcked-by: Alan Stern --- 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(_class->kref, release_usb_class); + mutex_lock(_usb_class_mutex); + kref_put(_class->kref, release_usb_class); + mutex_unlock(_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(_usb_class_mutex); retval = init_usb_class(); + mutex_unlock(_usb_class_mutex); + if (retval) return retval; -- 1.7.9.5
Re: [PATCH v4] USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously
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 KaherAcked-by: Alan Stern --- 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(_class->kref, release_usb_class); + mutex_lock(_usb_class_mutex); + kref_put(_class->kref, release_usb_class); + mutex_unlock(_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(_usb_class_mutex); retval = init_usb_class(); + mutex_unlock(_usb_class_mutex); + if (retval) return retval; -- 1.7.9.5