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-rw-r--r--drivers/usb/usb-skeleton.c13
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);
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