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Tue, 03 Sep 2019 05:51:31 -0700 (PDT) Date: Tue, 3 Sep 2019 05:51:29 -0700 From: Guenter Roeck To: David Howells Cc: viro@zeniv.linux.org.uk, Casey Schaufler , Stephen Smalley , Greg Kroah-Hartman , nicolas.dichtel@6wind.com, raven@themaw.net, Christian Brauner , keyrings@vger.kernel.org, linux-usb@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 08/11] usb: Add USB subsystem notifications [ver #7] Message-ID: <20190903125129.GA18838@roeck-us.net> References: <156717343223.2204.15875738850129174524.stgit@warthog.procyon.org.uk> <156717350329.2204.7056537095039252263.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <156717350329.2204.7056537095039252263.stgit@warthog.procyon.org.uk> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, Aug 30, 2019 at 02:58:23PM +0100, David Howells wrote: > Add a USB subsystem notification mechanism whereby notifications about > hardware events such as device connection, disconnection, reset and I/O > errors, can be reported to a monitoring process asynchronously. > > Firstly, an event queue needs to be created: > > fd = open("/dev/event_queue", O_RDWR); > ioctl(fd, IOC_WATCH_QUEUE_SET_SIZE, page_size << n); > > then a notification can be set up to report USB notifications via that > queue: > > struct watch_notification_filter filter = { > .nr_filters = 1, > .filters = { > [0] = { > .type = WATCH_TYPE_USB_NOTIFY, > .subtype_filter[0] = UINT_MAX; > }, > }, > }; > ioctl(fd, IOC_WATCH_QUEUE_SET_FILTER, &filter); > notify_devices(fd, 12); > > After that, records will be placed into the queue when events occur on a > USB device or bus. Records are of the following format: > > struct usb_notification { > struct watch_notification watch; > __u32 error; > __u32 reserved; > __u8 name_len; > __u8 name[0]; > } *n; > > Where: > > n->watch.type will be WATCH_TYPE_USB_NOTIFY > > n->watch.subtype will be the type of notification, such as > NOTIFY_USB_DEVICE_ADD. > > n->watch.info & WATCH_INFO_LENGTH will indicate the length of the > record. > > n->watch.info & WATCH_INFO_ID will be the second argument to > device_notify(), shifted. > > n->error and n->reserved are intended to convey information such as > error codes, but are currently not used > > n->name_len and n->name convey the USB device name as an > unterminated string. This may be truncated - it is currently > limited to a maximum 63 chars. > > Note that it is permissible for event records to be of variable length - > or, at least, the length may be dependent on the subtype. > > Signed-off-by: David Howells > Reviewed-by: Greg Kroah-Hartman > cc: linux-usb@vger.kernel.org > --- > > Documentation/watch_queue.rst | 9 ++++++ > drivers/usb/core/Kconfig | 9 ++++++ > drivers/usb/core/devio.c | 56 ++++++++++++++++++++++++++++++++++++++ > drivers/usb/core/hub.c | 4 +++ > include/linux/usb.h | 18 ++++++++++++ > include/uapi/linux/watch_queue.h | 30 ++++++++++++++++++++ > 6 files changed, 125 insertions(+), 1 deletion(-) > > diff --git a/Documentation/watch_queue.rst b/Documentation/watch_queue.rst > index 5cc9c6924727..4087a8e670a8 100644 > --- a/Documentation/watch_queue.rst > +++ b/Documentation/watch_queue.rst > @@ -11,6 +11,8 @@ receive notifications from the kernel. This can be used in conjunction with:: > > * Block layer event notifications > > + * USB subsystem event notifications > + > > The notifications buffers can be enabled by: > > @@ -315,6 +317,13 @@ Any particular buffer can be fed from multiple sources. Sources include: > or temporary link loss. Watches of this type are set on the global device > watch list. > > + * WATCH_TYPE_USB_NOTIFY > + > + Notifications of this type indicate USB subsystem events, such as > + attachment, removal, reset and I/O errors. Separate events are generated > + for buses and devices. Watchpoints of this type are set on the global > + device watch list. > + > > Event Filtering > =============== > diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig > index ecaacc8ed311..57e7b649e48b 100644 > --- a/drivers/usb/core/Kconfig > +++ b/drivers/usb/core/Kconfig > @@ -102,3 +102,12 @@ config USB_AUTOSUSPEND_DELAY > The default value Linux has always had is 2 seconds. Change > this value if you want a different delay and cannot modify > the command line or module parameter. > + > +config USB_NOTIFICATIONS > + bool "Provide USB hardware event notifications" > + depends on USB && DEVICE_NOTIFICATIONS > + help > + This option provides support for getting hardware event notifications > + on USB devices and interfaces. This makes use of the > + /dev/watch_queue misc device to handle the notification buffer. > + device_notify(2) is used to set/remove watches. > diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c > index 9063ede411ae..b8572e4d6a1b 100644 > --- a/drivers/usb/core/devio.c > +++ b/drivers/usb/core/devio.c > @@ -41,6 +41,7 @@ > #include > #include > #include > +#include > > #include "usb.h" > > @@ -2660,13 +2661,68 @@ static void usbdev_remove(struct usb_device *udev) > } > } > > +#ifdef CONFIG_USB_NOTIFICATIONS > +static noinline void post_usb_notification(const char *devname, > + enum usb_notification_type subtype, > + u32 error) > +{ > + unsigned int gran = WATCH_LENGTH_GRANULARITY; > + unsigned int name_len, n_len; > + u64 id = 0; /* Might want to put a dev# here. */ > + > + struct { > + struct usb_notification n; > + char more_name[USB_NOTIFICATION_MAX_NAME_LEN - > + (sizeof(struct usb_notification) - > + offsetof(struct usb_notification, name))]; > + } n; > + > + name_len = strlen(devname); > + name_len = min_t(size_t, name_len, USB_NOTIFICATION_MAX_NAME_LEN); > + n_len = round_up(offsetof(struct usb_notification, name) + name_len, > + gran) / gran; > + > + memset(&n, 0, sizeof(n)); > + memcpy(n.n.name, devname, n_len); > + > + n.n.watch.type = WATCH_TYPE_USB_NOTIFY; > + n.n.watch.subtype = subtype; > + n.n.watch.info = n_len; > + n.n.error = error; > + n.n.name_len = name_len; > + > + post_device_notification(&n.n.watch, id); > +} > + > +void post_usb_device_notification(const struct usb_device *udev, > + enum usb_notification_type subtype, u32 error) > +{ > + post_usb_notification(dev_name(&udev->dev), subtype, error); > +} > + > +void post_usb_bus_notification(const struct usb_bus *ubus, > + enum usb_notification_type subtype, u32 error) > +{ > + post_usb_notification(ubus->bus_name, subtype, error); > +} > +#endif > + > static int usbdev_notify(struct notifier_block *self, > unsigned long action, void *dev) > { > switch (action) { > case USB_DEVICE_ADD: > + post_usb_device_notification(dev, NOTIFY_USB_DEVICE_ADD, 0); > break; > case USB_DEVICE_REMOVE: > + post_usb_device_notification(dev, NOTIFY_USB_DEVICE_REMOVE, 0); > + usbdev_remove(dev); > + break; > + case USB_BUS_ADD: > + post_usb_bus_notification(dev, NOTIFY_USB_BUS_ADD, 0); > + break; > + case USB_BUS_REMOVE: > + post_usb_bus_notification(dev, NOTIFY_USB_BUS_REMOVE, 0); > usbdev_remove(dev); This added call to usbdev_remove() results in a crash when running the qemu "tosa" emulation. Removing the call fixes the problem. Guenter From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Date: Tue, 03 Sep 2019 12:51:29 +0000 Subject: Re: [PATCH 08/11] usb: Add USB subsystem notifications [ver #7] Message-Id: <20190903125129.GA18838@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: References: <156717343223.2204.15875738850129174524.stgit@warthog.procyon.org.uk> <156717350329.2204.7056537095039252263.stgit@warthog.procyon.org.uk> In-Reply-To: <156717350329.2204.7056537095039252263.stgit@warthog.procyon.org.uk> To: David Howells Cc: viro@zeniv.linux.org.uk, Casey Schaufler , Stephen Smalley , Greg Kroah-Hartman , nicolas.dichtel@6wind.com, raven@themaw.net, Christian Brauner , keyrings@vger.kernel.org, linux-usb@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org On Fri, Aug 30, 2019 at 02:58:23PM +0100, David Howells wrote: > Add a USB subsystem notification mechanism whereby notifications about > hardware events such as device connection, disconnection, reset and I/O > errors, can be reported to a monitoring process asynchronously. > > Firstly, an event queue needs to be created: > > fd = open("/dev/event_queue", O_RDWR); > ioctl(fd, IOC_WATCH_QUEUE_SET_SIZE, page_size << n); > > then a notification can be set up to report USB notifications via that > queue: > > struct watch_notification_filter filter = { > .nr_filters = 1, > .filters = { > [0] = { > .type = WATCH_TYPE_USB_NOTIFY, > .subtype_filter[0] = UINT_MAX; > }, > }, > }; > ioctl(fd, IOC_WATCH_QUEUE_SET_FILTER, &filter); > notify_devices(fd, 12); > > After that, records will be placed into the queue when events occur on a > USB device or bus. Records are of the following format: > > struct usb_notification { > struct watch_notification watch; > __u32 error; > __u32 reserved; > __u8 name_len; > __u8 name[0]; > } *n; > > Where: > > n->watch.type will be WATCH_TYPE_USB_NOTIFY > > n->watch.subtype will be the type of notification, such as > NOTIFY_USB_DEVICE_ADD. > > n->watch.info & WATCH_INFO_LENGTH will indicate the length of the > record. > > n->watch.info & WATCH_INFO_ID will be the second argument to > device_notify(), shifted. > > n->error and n->reserved are intended to convey information such as > error codes, but are currently not used > > n->name_len and n->name convey the USB device name as an > unterminated string. This may be truncated - it is currently > limited to a maximum 63 chars. > > Note that it is permissible for event records to be of variable length - > or, at least, the length may be dependent on the subtype. > > Signed-off-by: David Howells > Reviewed-by: Greg Kroah-Hartman > cc: linux-usb@vger.kernel.org > --- > > Documentation/watch_queue.rst | 9 ++++++ > drivers/usb/core/Kconfig | 9 ++++++ > drivers/usb/core/devio.c | 56 ++++++++++++++++++++++++++++++++++++++ > drivers/usb/core/hub.c | 4 +++ > include/linux/usb.h | 18 ++++++++++++ > include/uapi/linux/watch_queue.h | 30 ++++++++++++++++++++ > 6 files changed, 125 insertions(+), 1 deletion(-) > > diff --git a/Documentation/watch_queue.rst b/Documentation/watch_queue.rst > index 5cc9c6924727..4087a8e670a8 100644 > --- a/Documentation/watch_queue.rst > +++ b/Documentation/watch_queue.rst > @@ -11,6 +11,8 @@ receive notifications from the kernel. This can be used in conjunction with:: > > * Block layer event notifications > > + * USB subsystem event notifications > + > > The notifications buffers can be enabled by: > > @@ -315,6 +317,13 @@ Any particular buffer can be fed from multiple sources. Sources include: > or temporary link loss. Watches of this type are set on the global device > watch list. > > + * WATCH_TYPE_USB_NOTIFY > + > + Notifications of this type indicate USB subsystem events, such as > + attachment, removal, reset and I/O errors. Separate events are generated > + for buses and devices. Watchpoints of this type are set on the global > + device watch list. > + > > Event Filtering > =======> diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig > index ecaacc8ed311..57e7b649e48b 100644 > --- a/drivers/usb/core/Kconfig > +++ b/drivers/usb/core/Kconfig > @@ -102,3 +102,12 @@ config USB_AUTOSUSPEND_DELAY > The default value Linux has always had is 2 seconds. Change > this value if you want a different delay and cannot modify > the command line or module parameter. > + > +config USB_NOTIFICATIONS > + bool "Provide USB hardware event notifications" > + depends on USB && DEVICE_NOTIFICATIONS > + help > + This option provides support for getting hardware event notifications > + on USB devices and interfaces. This makes use of the > + /dev/watch_queue misc device to handle the notification buffer. > + device_notify(2) is used to set/remove watches. > diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c > index 9063ede411ae..b8572e4d6a1b 100644 > --- a/drivers/usb/core/devio.c > +++ b/drivers/usb/core/devio.c > @@ -41,6 +41,7 @@ > #include > #include > #include > +#include > > #include "usb.h" > > @@ -2660,13 +2661,68 @@ static void usbdev_remove(struct usb_device *udev) > } > } > > +#ifdef CONFIG_USB_NOTIFICATIONS > +static noinline void post_usb_notification(const char *devname, > + enum usb_notification_type subtype, > + u32 error) > +{ > + unsigned int gran = WATCH_LENGTH_GRANULARITY; > + unsigned int name_len, n_len; > + u64 id = 0; /* Might want to put a dev# here. */ > + > + struct { > + struct usb_notification n; > + char more_name[USB_NOTIFICATION_MAX_NAME_LEN - > + (sizeof(struct usb_notification) - > + offsetof(struct usb_notification, name))]; > + } n; > + > + name_len = strlen(devname); > + name_len = min_t(size_t, name_len, USB_NOTIFICATION_MAX_NAME_LEN); > + n_len = round_up(offsetof(struct usb_notification, name) + name_len, > + gran) / gran; > + > + memset(&n, 0, sizeof(n)); > + memcpy(n.n.name, devname, n_len); > + > + n.n.watch.type = WATCH_TYPE_USB_NOTIFY; > + n.n.watch.subtype = subtype; > + n.n.watch.info = n_len; > + n.n.error = error; > + n.n.name_len = name_len; > + > + post_device_notification(&n.n.watch, id); > +} > + > +void post_usb_device_notification(const struct usb_device *udev, > + enum usb_notification_type subtype, u32 error) > +{ > + post_usb_notification(dev_name(&udev->dev), subtype, error); > +} > + > +void post_usb_bus_notification(const struct usb_bus *ubus, > + enum usb_notification_type subtype, u32 error) > +{ > + post_usb_notification(ubus->bus_name, subtype, error); > +} > +#endif > + > static int usbdev_notify(struct notifier_block *self, > unsigned long action, void *dev) > { > switch (action) { > case USB_DEVICE_ADD: > + post_usb_device_notification(dev, NOTIFY_USB_DEVICE_ADD, 0); > break; > case USB_DEVICE_REMOVE: > + post_usb_device_notification(dev, NOTIFY_USB_DEVICE_REMOVE, 0); > + usbdev_remove(dev); > + break; > + case USB_BUS_ADD: > + post_usb_bus_notification(dev, NOTIFY_USB_BUS_ADD, 0); > + break; > + case USB_BUS_REMOVE: > + post_usb_bus_notification(dev, NOTIFY_USB_BUS_REMOVE, 0); > usbdev_remove(dev); This added call to usbdev_remove() results in a crash when running the qemu "tosa" emulation. Removing the call fixes the problem. Guenter