[PATCH] staging: comedi: add error handling for vmap

[Zhouyang Jia]

When vmap fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling vmap.

Signed-off-by: Zhouyang Jia <jiazhouyang09@xxxxxxxxx>
---
 drivers/staging/comedi/comedi_buf.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c
index f693c2c..5e48693 100644
--- a/drivers/staging/comedi/comedi_buf.c
+++ b/drivers/staging/comedi/comedi_buf.c
@@ -132,9 +132,12 @@ static void __comedi_buf_alloc(struct comedi_device *dev,
 	spin_unlock_irqrestore(&s->spin_lock, flags);
 
 	/* vmap the prealloc_buf if all the pages were allocated */
-	if (i == n_pages)
+	if (i == n_pages) {
 		async->prealloc_buf = vmap(pages, n_pages, VM_MAP,
 					   COMEDI_PAGE_PROTECTION);
+		if (!async->prealloc_buf)
+			dev_err(dev->class_dev, "failed to vmap pages\n");
+	}
 
 	vfree(pages);
 }
-- 
2.7.4