From: Oliver Neukum <oliver@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
drivers/usb/usb-skeleton.c | 13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
index 5ffa3e2..768fda9 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);
--
1.6.4.2
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
