Messages in this thread Patch in this message | | | From | Duncan Sands <> | Subject | [PATCH 1/9] USB usbfs: take a reference to the usb device | Date | Wed, 14 Apr 2004 12:29:26 +0200 |
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Hi Greg, this is the first of a series of patches that replace the per-file semaphore ps->devsem with the per-device semaphore ps->dev->serialize. The role of devsem was to protect against device disconnection. This can be done equally well using ps->dev->serialize. On the other hand, ps->dev->serialize protects against configuration and other changes, and has already been introduced into usbfs in several places. Using just one semaphore simplifies the code and removes some remaining race conditions. It should also fix the oopses some people have been seeing. In this first patch, a reference is taken to the usb device as long as the usbfs file is open. That way we can use ps->dev->serialize for as long as ps exists.
devio.c | 27 ++++++++++++++++----------- inode.c | 3 --- 2 files changed, 16 insertions(+), 14 deletions(-)
diff -Nru a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c --- a/drivers/usb/core/devio.c Wed Apr 14 12:15:29 2004 +++ b/drivers/usb/core/devio.c Wed Apr 14 12:15:29 2004 @@ -60,6 +60,11 @@ struct urb *urb; }; +static inline int connected (struct usb_device *dev) +{ + return dev->state != USB_STATE_NOTATTACHED; +} + static loff_t usbdev_lseek(struct file *file, loff_t offset, int orig) { loff_t ret; @@ -94,7 +99,7 @@ pos = *ppos; down_read(&ps->devsem); - if (!ps->dev) { + if (!connected(ps->dev)) { ret = -ENODEV; goto err; } else if (pos < 0) { @@ -343,8 +348,6 @@ * all pending I/O requests; 2.6 does that. */ - /* prevent new I/O requests */ - ps->dev = 0; clear_bit(intf->cur_altsetting->desc.bInterfaceNumber, &ps->ifclaimed); usb_set_intfdata (intf, NULL); @@ -365,7 +368,7 @@ struct usb_interface *iface; int err; - if (intf >= 8*sizeof(ps->ifclaimed) || !dev + if (intf >= 8*sizeof(ps->ifclaimed) || intf >= dev->actconfig->desc.bNumInterfaces) return -EINVAL; /* already claimed */ @@ -506,7 +509,7 @@ lock_kernel(); ret = -ENOENT; - dev = inode->u.generic_ip; + dev = usb_get_dev(inode->u.generic_ip); if (!dev) { kfree(ps); goto out; @@ -540,13 +543,15 @@ lock_kernel(); list_del_init(&ps->list); - if (ps->dev) { + if (connected(ps->dev)) { for (i = 0; ps->ifclaimed && i < 8*sizeof(ps->ifclaimed); i++) if (test_bit(i, &ps->ifclaimed)) releaseintf(ps, i); + destroy_all_async(ps); } unlock_kernel(); - destroy_all_async(ps); + usb_put_dev(ps->dev); + ps->dev = NULL; kfree(ps); return 0; } @@ -1015,7 +1020,7 @@ int ret; add_wait_queue(&ps->wait, &wait); - while (ps->dev) { + while (connected(ps->dev)) { __set_current_state(TASK_INTERRUPTIBLE); if ((as = async_getcompleted(ps))) break; @@ -1125,7 +1130,7 @@ } } - if (!ps->dev) { + if (!connected(ps->dev)) { if (buf) kfree(buf); return -ENODEV; @@ -1195,7 +1200,7 @@ if (!(file->f_mode & FMODE_WRITE)) return -EPERM; down_read(&ps->devsem); - if (!ps->dev) { + if (!connected(ps->dev)) { up_read(&ps->devsem); return -ENODEV; } @@ -1293,7 +1298,7 @@ poll_wait(file, &ps->wait, wait); if (file->f_mode & FMODE_WRITE && !list_empty(&ps->async_completed)) mask |= POLLOUT | POLLWRNORM; - if (!ps->dev) + if (!connected(ps->dev)) mask |= POLLERR | POLLHUP; return mask; } diff -Nru a/drivers/usb/core/inode.c b/drivers/usb/core/inode.c --- a/drivers/usb/core/inode.c Wed Apr 14 12:15:29 2004 +++ b/drivers/usb/core/inode.c Wed Apr 14 12:15:29 2004 @@ -717,9 +717,6 @@ while (!list_empty(&dev->filelist)) { ds = list_entry(dev->filelist.next, struct dev_state, list); list_del_init(&ds->list); - down_write(&ds->devsem); - ds->dev = NULL; - up_write(&ds->devsem); if (ds->discsignr) { sinfo.si_signo = SIGPIPE; sinfo.si_errno = EPIPE; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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