From 8ccef0df54642f0f72f922d8aa57e8b290e31671 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 21 Jun 2007 16:26:46 -0400 Subject: [PATCH] USB: Fix off-by-1 error in the scatter-gather library The loop in usb_sg_wait() is structured in a way that makes it hard to tell, when the loop exits, whether or not the last URB submission succeeded. This patch (as928) changes it from a "for" loop to a "while" loop and keeps "i" always equal to the number of successful submissions. This fixes an off-by-one error which can show up when the first URB submission fails. The patch also removes a couple of lines that initialize fields which don't need to be initialized. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/message.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c index f9fed34..4c14323 100644 --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -404,8 +404,6 @@ int usb_sg_init ( io->urbs [i]->complete = sg_complete; io->urbs [i]->context = io; - io->urbs [i]->status = -EINPROGRESS; - io->urbs [i]->actual_length = 0; /* * Some systems need to revert to PIO when DMA is temporarily @@ -499,7 +497,8 @@ void usb_sg_wait (struct usb_sg_request *io) /* queue the urbs. */ spin_lock_irq (&io->lock); - for (i = 0; i < entries && !io->status; i++) { + i = 0; + while (i < entries && !io->status) { int retval; io->urbs [i]->dev = io->dev; @@ -516,7 +515,6 @@ void usb_sg_wait (struct usb_sg_request *io) case -ENOMEM: io->urbs[i]->dev = NULL; retval = 0; - i--; yield (); break; @@ -527,6 +525,7 @@ void usb_sg_wait (struct usb_sg_request *io) * URBs are queued at once; N milliseconds? */ case 0: + ++i; cpu_relax (); break; -- 2.7.4