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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 <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
hifive-unleashed-5.1
Oliver Neukum 2009-09-09 10:23:35 +02:00 committed by Greg Kroah-Hartman
parent e7389cc9a7
commit 7981998673
1 changed files with 10 additions and 3 deletions
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13
drivers/usb/usb-skeleton.c
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@ -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);