Nov 19 2015

mtd: brcmnand: improve memory management 

Author: Julia Lawall <julia.lawall@lip6.fr>

This patch addresses two related memory management issues in the probe
function:

1. for_each_available_child_of_node performs an of_node_get on each
iteration, so a break out of the loop requires an of_node_put.

A simplified version of the semantic patch that fixes this problem is as
follows (http://coccinelle.lip6.fr):

// 
@@
expression root,e;
local idexpression child;
@@

 for_each_available_child_of_node(root, child) {
   ... when != of_node_put(child)
       when != e = child
(
   return child;
|
+  of_node_put(child);
?  return ...;
)
   ...
 }
// 

2. The devm_kzalloc'd data is not used if brcmnand_init_cs fails.  Free it
immediately, using devm_kfree in this case, instead of waiting for the
remove function.

Signed-off-by: Julia Lawall 
Signed-off-by: Brian Norris 

---
 drivers/mtd/nand/brcmnand/brcmnand.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
 
diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c
index 8feee1e..ad756f6 100644
--- a/drivers/mtd/nand/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/brcmnand/brcmnand.c
@@ -2233,15 +2233,19 @@ int brcmnand_probe(struct platform_device *pdev, struct brcmnand_soc *soc)
 			struct brcmnand_host *host;
 
 			host = devm_kzalloc(dev, sizeof(*host), GFP_KERNEL);
-			if (!host)
+			if (!host) {
+				of_node_put(child);
 				return -ENOMEM;
+			}
 			host->pdev = pdev;
 			host->ctrl = ctrl;
 			host->of_node = child;
 
 			ret = brcmnand_init_cs(host);
-			if (ret)
+			if (ret) {
+				devm_kfree(dev, host);
 				continue; /* Try all chip-selects */
+			}
 
 			list_add_tail(&host->node, &ctrl->host_list);
 		}

qlambert