[PATCH 0/3] delete unneeded of_node_put

[PATCH 0/3] delete unneeded of_node_put

[Julia Lawall]

Device node iterators perform an of_node_put on each iteration, so putting
an of_node_put before going around to the next iteration results in a
double put.

The complete semantic patch that fixes this problem is as follows
(http://coccinelle.lip6.fr):

// <smpl>
@r exists@
expression e1,e2;
local idexpression n;
iterator name for_each_node_by_name, for_each_node_by_type,
for_each_compatible_node, for_each_matching_node,
for_each_matching_node_and_match, for_each_child_of_node,
for_each_available_child_of_node, for_each_node_with_property;
iterator i;
position p1,p2;
statement S;
@@

(
(
for_each_node_by_name(n,e1) S
|
for_each_node_by_type(n,e1) S
|
for_each_compatible_node(n,e1,e2) S
|
for_each_matching_node(n,e1) S
|
for_each_matching_node_and_match(n,e1,e2) S
|
for_each_child_of_node(e1,n) S
|
for_each_available_child_of_node(e1,n) S
|
for_each_node_with_property(n,e1) S
)
&
i@p1(...) {
   ... when != of_node_get(n)
       when any
   of_node_put@p2(n);
   ... when any
}
)

@s exists@
local idexpression r.n;
statement S;
position r.p1,r.p2;
iterator i;
@@

 of_node_put@p2(n);
 ... when any
 i@p1(..., n, ...)
 S

@depends on s@
local idexpression n;
position r.p2;
@@

- of_node_put@p2(n);
// </smpl>

---

 arch/arm/mach-exynos/pm_domains.c                 |    8 +++-----
 drivers/soc/qcom/smd.c                            |    4 +---
 drivers/video/fbdev/omap2/dss/omapdss-boot-init.c |    4 +---
 3 files changed, 5 insertions(+), 11 deletions(-)

[PATCH 1/3] video: omapdss: delete unneeded of_node_put

[Julia Lawall]

Device node iterators perform an of_node_put on each iteration, so putting
an of_node_put before a continue results in a double put.

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

// <smpl>
@@
expression root,e;
local idexpression child;
iterator i;
@@

 i(..., child, ...) {
   ... when != of_node_get(child)
*  of_node_put(child);
   ...
*  continue;
}
// </smpl>

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

---
 drivers/video/fbdev/omap2/dss/omapdss-boot-init.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/video/fbdev/omap2/dss/omapdss-boot-init.c b/drivers/video/fbdev/omap2/dss/omapdss-boot-init.c
index 8b6f6d5..136d304 100644
--- a/drivers/video/fbdev/omap2/dss/omapdss-boot-init.c
+++ b/drivers/video/fbdev/omap2/dss/omapdss-boot-init.c
@@ -199,10 +199,8 @@ static int __init omapdss_boot_init(void)
 	omapdss_walk_device(dss, true);
 
 	for_each_available_child_of_node(dss, child) {
-		if (!of_find_property(child, "compatible", NULL)) {
-			of_node_put(child);
+		if (!of_find_property(child, "compatible", NULL))
 			continue;
-		}
 
 		omapdss_walk_device(child, true);
 	}

[PATCH 2/3] soc: qcom: smd: delete unneeded of_node_put

[Julia Lawall]

Device node iterators perform an of_node_put on each iteration, so putting
an of_node_put before a continue results in a double put.

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

// <smpl>
@@
expression root,e;
local idexpression child;
iterator i;
@@

 i(..., child, ...) {
   ... when != of_node_get(child)
*  of_node_put(child);
   ...
*  continue;
}
// </smpl>

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

---
 drivers/soc/qcom/smd.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/soc/qcom/smd.c b/drivers/soc/qcom/smd.c
index 6da0463..8c7a489 100644
--- a/drivers/soc/qcom/smd.c
+++ b/drivers/soc/qcom/smd.c
@@ -916,10 +916,8 @@ static struct device_node *qcom_smd_match_channel(struct device_node *edge_node,
 	for_each_available_child_of_node(edge_node, child) {
 		key = "qcom,smd-channels";
 		ret = of_property_read_string(child, key, &name);
-		if (ret) {
-			of_node_put(child);
+		if (ret)
 			continue;
-		}
 
 		if (strcmp(name, channel) = 0)
 			return child;

[PATCH 3/3] ARM: EXYNOS: delete unneeded of_node_put

[Julia Lawall]

Device node iterators perform an of_node_put on each iteration, so putting
an of_node_put before going around to the next iteration results in a
double put.

Problem found using Coccinelle.

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

---
 arch/arm/mach-exynos/pm_domains.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/arm/mach-exynos/pm_domains.c b/arch/arm/mach-exynos/pm_domains.c
index 4a87e86..7c21760 100644
--- a/arch/arm/mach-exynos/pm_domains.c
+++ b/arch/arm/mach-exynos/pm_domains.c
@@ -200,15 +200,15 @@ no_clk:
 		args.args_count = 0;
 		child_domain = of_genpd_get_from_provider(&args);
 		if (IS_ERR(child_domain))
-			goto next_pd;
+			continue;
 
 		if (of_parse_phandle_with_args(np, "power-domains",
 					 "#power-domain-cells", 0, &args) != 0)
-			goto next_pd;
+			continue;
 
 		parent_domain = of_genpd_get_from_provider(&args);
 		if (IS_ERR(parent_domain))
-			goto next_pd;
+			continue;
 
 		if (pm_genpd_add_subdomain(parent_domain, child_domain))
 			pr_warn("%s failed to add subdomain: %s\n",
@@ -216,8 +216,6 @@ no_clk:
 		else
 			pr_info("%s has as child subdomain: %s.\n",
 				parent_domain->name, child_domain->name);
-next_pd:
-		of_node_put(np);
 	}
 
 	return 0;

Re: [PATCH 3/3] ARM: EXYNOS: delete unneeded of_node_put

[Javier Martinez Canillas]

Hello Julia,

On 10/12/2015 10:43 PM, Julia Lawall wrote:
> Device node iterators perform an of_node_put on each iteration, so putting
> an of_node_put before going around to the next iteration results in a
> double put.
> 
> Problem found using Coccinelle.
> 
> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
>

Krzysztof sent the same patch yesterday and was already applied:
https://lkml.org/lkml/2015/10/12/688

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America

Re: [PATCH 1/3] video: omapdss: delete unneeded of_node_put

[Tomi Valkeinen]

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On 12/10/15 23:43, Julia Lawall wrote:
> Device node iterators perform an of_node_put on each iteration, so putting
> an of_node_put before a continue results in a double put.
> 
> A simplified version of the semantic match that finds this problem is as
> follows (http://coccinelle.lip6.fr):
> 
> // <smpl>
> @@
> expression root,e;
> local idexpression child;
> iterator i;
> @@
> 
>  i(..., child, ...) {
>    ... when != of_node_get(child)
> *  of_node_put(child);
>    ...
> *  continue;
> }
> // </smpl>
> 
> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
> 
> ---
>  drivers/video/fbdev/omap2/dss/omapdss-boot-init.c |    4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)

Thanks, queued for 4.5.

 Tomi


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