From 798199867385417ba6494472e39c016e3340758c Mon Sep 17 00:00:00 2001 From: Oliver Neukum Date: Wed, 9 Sep 2009 10:23:35 +0200 Subject: [PATCH] USB: make usb-skeleton honor O_NONBLOCK in write path usb:usb-skeleton: honor O_NONBLOCK in write path nonblocking writes are allowed by using down_trylock if necessary to reserve an URB Signed-off-by: Oliver Neukum Signed-off-by: Greg Kroah-Hartman --- drivers/usb/usb-skeleton.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c index 5ffa3e246856..768fda9064e9 100644 --- a/drivers/usb/usb-skeleton.c +++ b/drivers/usb/usb-skeleton.c @@ -399,9 +399,16 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou goto exit; /* limit the number of URBs in flight to stop a user from using up all RAM */ - if (down_interruptible(&dev->limit_sem)) { - retval = -ERESTARTSYS; - goto exit; + if (!file->f_flags & O_NONBLOCK) { + if (down_interruptible(&dev->limit_sem)) { + retval = -ERESTARTSYS; + goto exit; + } + } else { + if (down_trylock(&dev->limit_sem)) { + retval = -EAGAIN; + goto exit; + } } spin_lock_irq(&dev->err_lock);