| Message ID | 20160125121720.GC1194@e106497-lin.cambridge.arm.com |
|---|---|
| State | New |
| Headers | show |
On Mon, 25 Jan 2016, liviu.dudau@arm.com wrote: > On Fri, Jan 22, 2016 at 11:38:38PM +0530, Amitoj Kaur Chawla wrote: > > for_each_compatible_node performs an of_node_get on each iteration, so > > to break out of the loop an of_node_put is required. > > > > Found using Coccinelle. The semantic patch used for this is as follows: > > > > // <smpl> > > @@ > > expression e; > > local idexpression n; > > @@ > > > > for_each_compatible_node(n, ...) { > > ... when != of_node_put(n) > > when != e = n > > ( > > return n; > > + of_node_put(n); > > ? return ...; > > ) > > ... > > } > > // </smpl> > > > > Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com> > > Hi Amitoj, > > > --- > > drivers/bus/vexpress-config.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c > > index 6575c0f..c3cb76b 100644 > > --- a/drivers/bus/vexpress-config.c > > +++ b/drivers/bus/vexpress-config.c > > @@ -192,8 +192,10 @@ static int __init vexpress_config_init(void) > > /* Need the config devices early, before the "normal" devices... */ > > for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") { > > err = vexpress_config_populate(node); > > - if (err) > > + if (err) { > > + of_node_put(node); > > break; > > + } > > This automatically generated patch only solves half of the problem (for the error > path). > > > } > > > > return err; > > -- > > 1.9.1 > > > > I feel that a better patch would be the following, where the node is released > regardless of the result of vexpress_config_populate(). > > --8<-------------------------------------------------------------------------- > diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c > index 6575c0f..c57453d 100644 > --- a/drivers/bus/vexpress-config.c > +++ b/drivers/bus/vexpress-config.c > @@ -192,6 +192,7 @@ static int __init vexpress_config_init(void) > /* Need the config devices early, before the "normal" devices... */ > for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") { > err = vexpress_config_populate(node); > + of_node_put(node); This is not correct. for_each_compatible_node will do the free if you go around the loop. This change would lead to a double free in the non error case. julia > if (err) > break; > } > -->8-------------------------------------------------------------------------- > > Best regards, > Liviu > > -- > ==================== > | I would like to | > | fix the world, | > | but they're not | > | giving me the | > \ source code! / > --------------- > ¯\_(ツ)_/¯ >
On Mon, Jan 25, 2016 at 01:24:44PM +0100, Julia Lawall wrote: > > > On Mon, 25 Jan 2016, liviu.dudau@arm.com wrote: > > > On Fri, Jan 22, 2016 at 11:38:38PM +0530, Amitoj Kaur Chawla wrote: > > > for_each_compatible_node performs an of_node_get on each iteration, so > > > to break out of the loop an of_node_put is required. > > > > > > Found using Coccinelle. The semantic patch used for this is as follows: > > > > > > // <smpl> > > > @@ > > > expression e; > > > local idexpression n; > > > @@ > > > > > > for_each_compatible_node(n, ...) { > > > ... when != of_node_put(n) > > > when != e = n > > > ( > > > return n; > > > + of_node_put(n); > > > ? return ...; > > > ) > > > ... > > > } > > > // </smpl> > > > > > > Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com> > > > > Hi Amitoj, > > > > > --- > > > drivers/bus/vexpress-config.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c > > > index 6575c0f..c3cb76b 100644 > > > --- a/drivers/bus/vexpress-config.c > > > +++ b/drivers/bus/vexpress-config.c > > > @@ -192,8 +192,10 @@ static int __init vexpress_config_init(void) > > > /* Need the config devices early, before the "normal" devices... */ > > > for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") { > > > err = vexpress_config_populate(node); > > > - if (err) > > > + if (err) { > > > + of_node_put(node); > > > break; > > > + } > > > > This automatically generated patch only solves half of the problem (for the error > > path). > > > > > } > > > > > > return err; > > > -- > > > 1.9.1 > > > > > > > I feel that a better patch would be the following, where the node is released > > regardless of the result of vexpress_config_populate(). > > > > --8<-------------------------------------------------------------------------- > > diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c > > index 6575c0f..c57453d 100644 > > --- a/drivers/bus/vexpress-config.c > > +++ b/drivers/bus/vexpress-config.c > > @@ -192,6 +192,7 @@ static int __init vexpress_config_init(void) > > /* Need the config devices early, before the "normal" devices... */ > > for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") { > > err = vexpress_config_populate(node); > > + of_node_put(node); > > This is not correct. for_each_compatible_node will do the free if you go > around the loop. This change would lead to a double free in the non error > case. You are correct and I withdraw my patch. For the original patch: Acked-by: Liviu Dudau <Liviu.Dudau@arm.com> Best regards, Liviu > > julia > > > if (err) > > break; > > } > > -->8--------------------------------------------------------------------------
diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c index 6575c0f..c57453d 100644 --- a/drivers/bus/vexpress-config.c +++ b/drivers/bus/vexpress-config.c @@ -192,6 +192,7 @@ static int __init vexpress_config_init(void) /* Need the config devices early, before the "normal" devices... */ for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") { err = vexpress_config_populate(node); + of_node_put(node); if (err) break; }