eth: fbnic: avoid double free when failing to DMA-map FW msg

BugLink: https://bugs.launchpad.net/bugs/2120812

[ Upstream commit 5bd1bafd4474ee26f504b41aba11f3e2a1175b88 ]

The semantics are that caller of fbnic_mbx_map_msg() retains
the ownership of the message on error. All existing callers
dutifully free the page.

Fixes: da3cde0 ("eth: fbnic: Add FW communication mechanism")
Reviewed-by: Alexander Duyck <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Noah Wager <[email protected]>
Signed-off-by: Stefan Bader <[email protected]>

Author: kuba-moo

drivers/net/ethernet/meta/fbnic/fbnic_fw.c

@@ -127,11 +127,8 @@ static int fbnic_mbx_map_msg(struct fbnic_dev *fbd, int mbx_idx,
 		return -EBUSY;
 
 	addr = dma_map_single(fbd->dev, msg, PAGE_SIZE, direction);
-	if (dma_mapping_error(fbd->dev, addr)) {
-		free_page((unsigned long)msg);
-
+	if (dma_mapping_error(fbd->dev, addr))
 		return -ENOSPC;
-	}
 
 	mbx->buf_info[tail].msg = msg;
 	mbx->buf_info[tail].addr = addr;