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Subject[PATCH 1/4] mtd: brcmnand: improve memory management
Date
This patch addresses several 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.

3. If the continue is not taken, then host is added to a list, that has a
lifetime beyond the end of the for_each_available_child_of_node loop body.
Thus, of_node_get is needed on child, which is referenced by host. A
corresponding of_node_put is needed in the remove function.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>

---

One could consider whether the of_node_get should be on host->of_node,
which looks more similar to the thing that is stored in the list. I used
child, to be more similar to the of_node_put in the same function.

drivers/mtd/nand/brcmnand/brcmnand.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c
index 2a437c7..b0cb55d 100644
--- a/drivers/mtd/nand/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/brcmnand/brcmnand.c
@@ -2237,16 +2237,20 @@ 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 */
-
+ }
+ of_node_get(child);
list_add_tail(&host->node, &ctrl->host_list);
}
}
@@ -2264,8 +2268,10 @@ int brcmnand_remove(struct platform_device *pdev)
struct brcmnand_controller *ctrl = dev_get_drvdata(&pdev->dev);
struct brcmnand_host *host;

- list_for_each_entry(host, &ctrl->host_list, node)
+ list_for_each_entry(host, &ctrl->host_list, node) {
+ of_node_put(host->of_node);
nand_release(&host->mtd);
+ }

dev_set_drvdata(&pdev->dev, NULL);



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