From 3f2cee73b650921b2e214bf487b2061a1c266504 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 29 Jan 2015 11:29:13 -0500 Subject: [PATCH] USB: usbfs: allow URBs to be reaped after disconnection The usbfs API has a peculiar hole: Users are not allowed to reap their URBs after the device has been disconnected. There doesn't seem to be any good reason for this; it is an ad-hoc inconsistency. The patch allows users to issue the USBDEVFS_REAPURB and USBDEVFS_REAPURBNDELAY ioctls (together with their 32-bit counterparts on 64-bit systems) even after the device is gone. If no URBs are pending for a disconnected device then the ioctls will return -ENODEV rather than -EAGAIN, because obviously no new URBs will ever be able to complete. The patch also adds a new capability flag for USBDEVFS_GET_CAPABILITIES to indicate that the reap-after-disconnect feature is supported. Signed-off-by: Alan Stern Tested-by: Chris Dickens Acked-by: Hans de Goede Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/devio.c | 63 +++++++++++++++++++++++---------------- include/uapi/linux/usbdevice_fs.h | 3 +- 2 files changed, 39 insertions(+), 27 deletions(-) diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 0b59731c3021..66abdbcfbfa5 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -1689,7 +1689,7 @@ static struct async *reap_as(struct usb_dev_state *ps) for (;;) { __set_current_state(TASK_INTERRUPTIBLE); as = async_getcompleted(ps); - if (as) + if (as || !connected(ps)) break; if (signal_pending(current)) break; @@ -1712,7 +1712,7 @@ static int proc_reapurb(struct usb_dev_state *ps, void __user *arg) } if (signal_pending(current)) return -EINTR; - return -EIO; + return -ENODEV; } static int proc_reapurbnonblock(struct usb_dev_state *ps, void __user *arg) @@ -1721,10 +1721,11 @@ static int proc_reapurbnonblock(struct usb_dev_state *ps, void __user *arg) struct async *as; as = async_getcompleted(ps); - retval = -EAGAIN; if (as) { retval = processcompl(as, (void __user * __user *)arg); free_async(as); + } else { + retval = (connected(ps) ? -EAGAIN : -ENODEV); } return retval; } @@ -1854,7 +1855,7 @@ static int proc_reapurb_compat(struct usb_dev_state *ps, void __user *arg) } if (signal_pending(current)) return -EINTR; - return -EIO; + return -ENODEV; } static int proc_reapurbnonblock_compat(struct usb_dev_state *ps, void __user *arg) @@ -1862,11 +1863,12 @@ static int proc_reapurbnonblock_compat(struct usb_dev_state *ps, void __user *ar int retval; struct async *as; - retval = -EAGAIN; as = async_getcompleted(ps); if (as) { retval = processcompl_compat(as, (void __user * __user *)arg); free_async(as); + } else { + retval = (connected(ps) ? -EAGAIN : -ENODEV); } return retval; } @@ -2038,7 +2040,8 @@ static int proc_get_capabilities(struct usb_dev_state *ps, void __user *arg) { __u32 caps; - caps = USBDEVFS_CAP_ZERO_PACKET | USBDEVFS_CAP_NO_PACKET_SIZE_LIM; + caps = USBDEVFS_CAP_ZERO_PACKET | USBDEVFS_CAP_NO_PACKET_SIZE_LIM | + USBDEVFS_CAP_REAP_AFTER_DISCONNECT; if (!ps->dev->bus->no_stop_on_short) caps |= USBDEVFS_CAP_BULK_CONTINUATION; if (ps->dev->bus->sg_tablesize) @@ -2138,6 +2141,32 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd, return -EPERM; usb_lock_device(dev); + + /* Reap operations are allowed even after disconnection */ + switch (cmd) { + case USBDEVFS_REAPURB: + snoop(&dev->dev, "%s: REAPURB\n", __func__); + ret = proc_reapurb(ps, p); + goto done; + + case USBDEVFS_REAPURBNDELAY: + snoop(&dev->dev, "%s: REAPURBNDELAY\n", __func__); + ret = proc_reapurbnonblock(ps, p); + goto done; + +#ifdef CONFIG_COMPAT + case USBDEVFS_REAPURB32: + snoop(&dev->dev, "%s: REAPURB32\n", __func__); + ret = proc_reapurb_compat(ps, p); + goto done; + + case USBDEVFS_REAPURBNDELAY32: + snoop(&dev->dev, "%s: REAPURBNDELAY32\n", __func__); + ret = proc_reapurbnonblock_compat(ps, p); + goto done; +#endif + } + if (!connected(ps)) { usb_unlock_device(dev); return -ENODEV; @@ -2231,16 +2260,6 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd, inode->i_mtime = CURRENT_TIME; break; - case USBDEVFS_REAPURB32: - snoop(&dev->dev, "%s: REAPURB32\n", __func__); - ret = proc_reapurb_compat(ps, p); - break; - - case USBDEVFS_REAPURBNDELAY32: - snoop(&dev->dev, "%s: REAPURBNDELAY32\n", __func__); - ret = proc_reapurbnonblock_compat(ps, p); - break; - case USBDEVFS_IOCTL32: snoop(&dev->dev, "%s: IOCTL32\n", __func__); ret = proc_ioctl_compat(ps, ptr_to_compat(p)); @@ -2252,16 +2271,6 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd, ret = proc_unlinkurb(ps, p); break; - case USBDEVFS_REAPURB: - snoop(&dev->dev, "%s: REAPURB\n", __func__); - ret = proc_reapurb(ps, p); - break; - - case USBDEVFS_REAPURBNDELAY: - snoop(&dev->dev, "%s: REAPURBNDELAY\n", __func__); - ret = proc_reapurbnonblock(ps, p); - break; - case USBDEVFS_DISCSIGNAL: snoop(&dev->dev, "%s: DISCSIGNAL\n", __func__); ret = proc_disconnectsignal(ps, p); @@ -2304,6 +2313,8 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd, ret = proc_free_streams(ps, p); break; } + + done: usb_unlock_device(dev); if (ret >= 0) inode->i_atime = CURRENT_TIME; diff --git a/include/uapi/linux/usbdevice_fs.h b/include/uapi/linux/usbdevice_fs.h index abe5f4bd4d82..019ba1e0799a 100644 --- a/include/uapi/linux/usbdevice_fs.h +++ b/include/uapi/linux/usbdevice_fs.h @@ -128,11 +128,12 @@ struct usbdevfs_hub_portinfo { char port [127]; /* e.g. port 3 connects to device 27 */ }; -/* Device capability flags */ +/* System and bus capability flags */ #define USBDEVFS_CAP_ZERO_PACKET 0x01 #define USBDEVFS_CAP_BULK_CONTINUATION 0x02 #define USBDEVFS_CAP_NO_PACKET_SIZE_LIM 0x04 #define USBDEVFS_CAP_BULK_SCATTER_GATHER 0x08 +#define USBDEVFS_CAP_REAP_AFTER_DISCONNECT 0x10 /* USBDEVFS_DISCONNECT_CLAIM flags & struct */ -- 2.11.0