From: Tasos Sahanidis tasos@tasossah.com
commit 0543e4e8852ef5ff1809ae62f1ea963e2ab23b66 upstream.
Since commit ae8709b296d8 ("USB: core: Make do_proc_control() and do_proc_bulk() killable") if a device has the USB_QUIRK_DELAY_CTRL_MSG quirk set, it will temporarily block all other URBs (e.g. interrupts) while sleeping due to a control.
This results in noticeable delays when, for example, a userspace usbfs application is sending URB interrupts at a high rate to a keyboard and simultaneously updates the lock indicators using controls. Interrupts with direction set to IN are also affected by this, meaning that delivery of HID reports (containing scancodes) to the usbfs application is delayed as well.
This patch fixes the regression by calling msleep() while the device mutex is unlocked, as was the case originally with usb_control_msg().
Fixes: ae8709b296d8 ("USB: core: Make do_proc_control() and do_proc_bulk() killable") Cc: stable stable@kernel.org Acked-by: Alan Stern stern@rowland.harvard.edu Signed-off-by: Tasos Sahanidis tasos@tasossah.com Link: https://lore.kernel.org/r/3e299e2a-13b9-ddff-7fee-6845e868bc06@tasossah.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/core/devio.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-)
--- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -1197,12 +1197,16 @@ static int do_proc_control(struct usb_de
usb_unlock_device(dev); i = usbfs_start_wait_urb(urb, tmo, &actlen); + + /* Linger a bit, prior to the next control message. */ + if (dev->quirks & USB_QUIRK_DELAY_CTRL_MSG) + msleep(200); usb_lock_device(dev); snoop_urb(dev, NULL, pipe, actlen, i, COMPLETE, tbuf, actlen); if (!i && actlen) { if (copy_to_user(ctrl->data, tbuf, actlen)) { ret = -EFAULT; - goto recv_fault; + goto done; } } } else { @@ -1219,6 +1223,10 @@ static int do_proc_control(struct usb_de
usb_unlock_device(dev); i = usbfs_start_wait_urb(urb, tmo, &actlen); + + /* Linger a bit, prior to the next control message. */ + if (dev->quirks & USB_QUIRK_DELAY_CTRL_MSG) + msleep(200); usb_lock_device(dev); snoop_urb(dev, NULL, pipe, actlen, i, COMPLETE, NULL, 0); } @@ -1230,10 +1238,6 @@ static int do_proc_control(struct usb_de } ret = (i < 0 ? i : actlen);
- recv_fault: - /* Linger a bit, prior to the next control message. */ - if (dev->quirks & USB_QUIRK_DELAY_CTRL_MSG) - msleep(200); done: kfree(dr); usb_free_urb(urb);