From 0864c7a9286b02319d3db2103bada1c2269c1e1e Mon Sep 17 00:00:00 2001 From: David Brownell Date: Tue, 16 Jan 2007 22:53:58 -0800 Subject: [PATCH] USB: gadgetfs simplifications This simplifies event reading by eliminating arithmetic and being more direct/obvious, and tweaks some debug messages slightly. The math elimination will change timings, sometimes enough to allow a race to appear. Signed-off-by: David Brownell Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/inode.c | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-) diff --git a/drivers/usb/gadget/inode.c b/drivers/usb/gadget/inode.c index cbdcb3c10c5..ea8e3160d05 100644 --- a/drivers/usb/gadget/inode.c +++ b/drivers/usb/gadget/inode.c @@ -1062,39 +1062,36 @@ scan: /* return queued events right away */ if (dev->ev_next != 0) { unsigned i, n; - int tmp = dev->ev_next; - len = min (len, tmp * sizeof (struct usb_gadgetfs_event)); n = len / sizeof (struct usb_gadgetfs_event); + if (dev->ev_next < n) + n = dev->ev_next; - /* ep0 can't deliver events when STATE_DEV_SETUP */ + /* ep0 i/o has special semantics during STATE_DEV_SETUP */ for (i = 0; i < n; i++) { if (dev->event [i].type == GADGETFS_SETUP) { - len = i + 1; - len *= sizeof (struct usb_gadgetfs_event); - n = 0; + dev->state = STATE_DEV_SETUP; + n = i + 1; break; } } spin_unlock_irq (&dev->lock); + len = n * sizeof (struct usb_gadgetfs_event); if (copy_to_user (buf, &dev->event, len)) retval = -EFAULT; else retval = len; if (len > 0) { - len /= sizeof (struct usb_gadgetfs_event); - /* NOTE this doesn't guard against broken drivers; * concurrent ep0 readers may lose events. */ spin_lock_irq (&dev->lock); - dev->ev_next -= len; - if (dev->ev_next != 0) - memmove (&dev->event, &dev->event [len], + if (dev->ev_next > n) { + memmove(&dev->event[0], &dev->event[n], sizeof (struct usb_gadgetfs_event) - * (tmp - len)); - if (n == 0) - dev->state = STATE_DEV_SETUP; + * (dev->ev_next - n)); + } + dev->ev_next -= n; spin_unlock_irq (&dev->lock); } return retval; @@ -1149,7 +1146,7 @@ next_event (struct dev_data *dev, enum usb_gadgetfs_event_type type) for (i = 0; i != dev->ev_next; i++) { if (dev->event [i].type != type) continue; - DBG (dev, "discard old event %d\n", type); + DBG(dev, "discard old event[%d] %d\n", i, type); dev->ev_next--; if (i == dev->ev_next) break; @@ -1162,9 +1159,9 @@ next_event (struct dev_data *dev, enum usb_gadgetfs_event_type type) default: BUG (); } + VDEBUG(dev, "event[%d] = %d\n", dev->ev_next, type); event = &dev->event [dev->ev_next++]; BUG_ON (dev->ev_next > N_EVENT); - VDEBUG (dev, "ev %d, next %d\n", type, dev->ev_next); memset (event, 0, sizeof *event); event->type = type; return event; -- 2.20.1