ring: first unmap, then destroy ring buffer

In both, the RX_RING and TX_RING we need to unmap first and then destroy
the buffer, otherwise, we get a device or resource busy.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>

2 files changed, 6 insertions, 8 deletions

diff --git a/ring_rx.c b/ring_rx.c
index 4c5846c..5675a81 100644
--- a/ring_rx.c
+++ b/ring_rx.c
@@ -23,16 +23,15 @@ void destroy_rx_ring(int sock, struct ring *ring)
 {
 	int ret;
 
-	fmemset(&ring->layout, 0, sizeof(ring->layout));
+	munmap(ring->mm_space, ring->mm_len);
+	ring->mm_len = 0;
 
+	fmemset(&ring->layout, 0, sizeof(ring->layout));
 	ret = setsockopt(sock, SOL_PACKET, PACKET_RX_RING, &ring->layout,
 			 sizeof(ring->layout));
 	if (unlikely(ret))
 		panic("Cannot destroy the RX_RING!\n");
 
-	munmap(ring->mm_space, ring->mm_len);
-	ring->mm_len = 0;
-
 	xfree(ring->frames);
 }
 
diff --git a/ring_tx.c b/ring_tx.c
index 9869131..6804c43 100644
--- a/ring_tx.c
+++ b/ring_tx.c
@@ -33,16 +33,15 @@ void destroy_tx_ring(int sock, struct ring *ring)
 {
 	int ret;
 
-	fmemset(&ring->layout, 0, sizeof(ring->layout));
+	munmap(ring->mm_space, ring->mm_len);
+	ring->mm_len = 0;
 
+	fmemset(&ring->layout, 0, sizeof(ring->layout));
 	ret = setsockopt(sock, SOL_PACKET, PACKET_TX_RING, &ring->layout,
 			 sizeof(ring->layout));
 	if (unlikely(ret))
 		panic("Cannot destroy the TX_RING!\n");
 
-	munmap(ring->mm_space, ring->mm_len);
-	ring->mm_len = 0;
-
 	xfree(ring->frames);
 }