diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2023-01-31 15:49:04 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-03 11:41:49 +0100 |
| commit | a1e89c8b29d003a20ed2dae6bdae1598d1f23e42 (patch) | |
| tree | 2e6fc2f1665d42b7b79b3a46cdbdb949a43dc5a3 | |
| parent | 96d380d2ae98b880b4d409b652162e16bb387cbb (diff) | |
USB: core: Don't hold device lock while reading the "descriptors" sysfs file
commit 45bf39f8df7f05efb83b302c65ae3b9bc92b7065 upstream.
Ever since commit 83e83ecb79a8 ("usb: core: get config and string
descriptors for unauthorized devices") was merged in 2013, there has
been no mechanism for reallocating the rawdescriptors buffers in
struct usb_device after the initial enumeration. Before that commit,
the buffers would be deallocated when a device was deauthorized and
reallocated when it was authorized and enumerated.
This means that the locking in the read_descriptors() routine is not
needed, since the buffers it reads will never be reallocated while the
routine is running. This locking can interfere with user programs
trying to read a hub's descriptors via sysfs while new child devices
of the hub are being initialized, since the hub is locked during this
procedure.
Since the locking in read_descriptors() hasn't been needed for over
nine years, we can remove it.
Reported-and-tested-by: Troels Liebe Bentsen <troels@connectedcars.dk>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: stable@vger.kernel.org
Link: https://lore.kernel.org/r/Y9l+wDTRbuZABzsE@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/core/hub.c | 5 | ||||
| -rw-r--r-- | drivers/usb/core/sysfs.c | 5 |
2 files changed, 2 insertions, 8 deletions
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 549bf04f29b2..f787e9771b1f 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2379,9 +2379,8 @@ static int usb_enumerate_device_otg(struct usb_device *udev) * usb_enumerate_device - Read device configs/intfs/otg (usbcore-internal) * @udev: newly addressed device (in ADDRESS state) * - * This is only called by usb_new_device() and usb_authorize_device() - * and FIXME -- all comments that apply to them apply here wrt to - * environment. + * This is only called by usb_new_device() -- all comments that apply there + * apply here wrt to environment. * * If the device is WUSB and not authorized, we don't attempt to read * the string descriptors, as they will be errored out by the device diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c index 2f594c88d905..f19694e69f5c 100644 --- a/drivers/usb/core/sysfs.c +++ b/drivers/usb/core/sysfs.c @@ -889,11 +889,7 @@ read_descriptors(struct file *filp, struct kobject *kobj, size_t srclen, n; int cfgno; void *src; - int retval; - retval = usb_lock_device_interruptible(udev); - if (retval < 0) - return -EINTR; /* The binary attribute begins with the device descriptor. * Following that are the raw descriptor entries for all the * configurations (config plus subsidiary descriptors). @@ -918,7 +914,6 @@ read_descriptors(struct file *filp, struct kobject *kobj, off -= srclen; } } - usb_unlock_device(udev); return count - nleft; } |