mtd: brcmnand: improve memory management

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=081976bcc0cbc84f5164fb7aa0e5cf597df6de9e
Commit:     081976bcc0cbc84f5164fb7aa0e5cf597df6de9e
Parent:     0401669797488feb055521cade69b1d0e81669db
Author:     Julia Lawall <julia.lawall at lip6.fr>
AuthorDate: Thu Nov 19 22:32:15 2015 +0100
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Mon Nov 30 17:54:05 2015 -0800

    mtd: brcmnand: improve memory management
    
    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):
    
    // <smpl>
    @@
    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 ...;
    )
       ...
     }
    // </smpl>
    
    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 <Julia.Lawall at lip6.fr>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 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);
 		}