| Message ID | 084fdd562690c08f1ee72bc08e63e8ee576dc86a.1693001599.git.christophe.jaillet@wanadoo.fr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: i2c: max9286: Fix some redundant of_node_put() calls | expand |
Hi Christophe On Sat, Aug 26, 2023 at 12:13:40AM +0200, Christophe JAILLET wrote: > This is odd to have a of_node_put() just after a for_each_child_of_node() > or a for_each_endpoint_of_node() loop. It should already be called > during the last iteration. Let's unwrap the calls: #define for_each_child_of_node(parent, child) \ for (child = of_get_next_child(parent, NULL); child != NULL; \ child = of_get_next_child(parent, child)) static struct device_node *__of_get_next_child(const struct device_node *node, struct device_node *prev) { struct device_node *next; if (!node) return NULL; next = prev ? prev->sibling : node->child; of_node_get(next); of_node_put(prev); return next; } Let's express the C for loop semantic as a while to help following the code: child = of_get_next_child(parent, NULL); while (child != NULL) child = of_get_next_child(parent, child); I concur that the last loop iteration the call to __of_get_next_child() will expand to next = NULL; of_node_get(NULL); of_node_put(prev) So it seems to me it is not necessary to put the node after for_each_child_of_node() ? In facts none of the other usages of for_each_child_of_node() in the kernel (the ones i checked at least) have a put() after the loop. > > Remove these calls. > > Fixes: 66d8c9d2422d ("media: i2c: Add MAX9286 driver") > Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com> Thanks j > --- > /!\ This patch is speculative, review with case /!\ > --- > drivers/media/i2c/max9286.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c > index 20e7c7cf5eeb..f27a69b1b727 100644 > --- a/drivers/media/i2c/max9286.c > +++ b/drivers/media/i2c/max9286.c > @@ -1450,7 +1450,6 @@ static int max9286_parse_dt(struct max9286_priv *priv) > > i2c_mux_mask |= BIT(id); > } > - of_node_put(node); > of_node_put(i2c_mux); > > /* Parse the endpoints */ > @@ -1514,7 +1513,6 @@ static int max9286_parse_dt(struct max9286_priv *priv) > priv->source_mask |= BIT(ep.port); > priv->nsources++; > } > - of_node_put(node); > > of_property_read_u32(dev->of_node, "maxim,bus-width", &priv->bus_width); > switch (priv->bus_width) { > -- > 2.34.1 >
Quoting Jacopo Mondi (2023-08-28 08:34:40) > Hi Christophe > > On Sat, Aug 26, 2023 at 12:13:40AM +0200, Christophe JAILLET wrote: > > This is odd to have a of_node_put() just after a for_each_child_of_node() > > or a for_each_endpoint_of_node() loop. It should already be called > > during the last iteration. > > Let's unwrap the calls: > > #define for_each_child_of_node(parent, child) \ > for (child = of_get_next_child(parent, NULL); child != NULL; \ > child = of_get_next_child(parent, child)) > > static struct device_node *__of_get_next_child(const struct device_node *node, > struct device_node *prev) > { > struct device_node *next; > > if (!node) > return NULL; > > next = prev ? prev->sibling : node->child; > of_node_get(next); > of_node_put(prev); > return next; > } > > Let's express the C for loop semantic as a while to help following the > code: > > child = of_get_next_child(parent, NULL); > while (child != NULL) > child = of_get_next_child(parent, child); > > I concur that the last loop iteration the call to > __of_get_next_child() will expand to > > next = NULL; > of_node_get(NULL); > of_node_put(prev) > > So it seems to me it is not necessary to put the node after > for_each_child_of_node() ? > > In facts none of the other usages of for_each_child_of_node() in the > kernel (the ones i checked at least) have a put() after the loop. I agree. As long as the loops don't use any break statement - there shouldn't be any _put() after the completion of the loop. That would make a good cocci script - make sure these iterators do not use 'break' internally - as that would then conflict! Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com> > > > > > Remove these calls. > > > > Fixes: 66d8c9d2422d ("media: i2c: Add MAX9286 driver") > > Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> > > Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com> > > Thanks > j > > > --- > > /!\ This patch is speculative, review with case /!\ > > --- > > drivers/media/i2c/max9286.c | 2 -- > > 1 file changed, 2 deletions(-) > > > > diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c > > index 20e7c7cf5eeb..f27a69b1b727 100644 > > --- a/drivers/media/i2c/max9286.c > > +++ b/drivers/media/i2c/max9286.c > > @@ -1450,7 +1450,6 @@ static int max9286_parse_dt(struct max9286_priv *priv) > > > > i2c_mux_mask |= BIT(id); > > } > > - of_node_put(node); > > of_node_put(i2c_mux); > > > > /* Parse the endpoints */ > > @@ -1514,7 +1513,6 @@ static int max9286_parse_dt(struct max9286_priv *priv) > > priv->source_mask |= BIT(ep.port); > > priv->nsources++; > > } > > - of_node_put(node); > > > > of_property_read_u32(dev->of_node, "maxim,bus-width", &priv->bus_width); > > switch (priv->bus_width) { > > -- > > 2.34.1 > >
Hi Christophe, Thank you for the patch. On Sat, Aug 26, 2023 at 12:13:40AM +0200, Christophe JAILLET wrote: > This is odd to have a of_node_put() just after a for_each_child_of_node() > or a for_each_endpoint_of_node() loop. It should already be called > during the last iteration. > > Remove these calls. > > Fixes: 66d8c9d2422d ("media: i2c: Add MAX9286 driver") > Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> > --- > /!\ This patch is speculative, review with case /!\ > --- > drivers/media/i2c/max9286.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c > index 20e7c7cf5eeb..f27a69b1b727 100644 > --- a/drivers/media/i2c/max9286.c > +++ b/drivers/media/i2c/max9286.c > @@ -1450,7 +1450,6 @@ static int max9286_parse_dt(struct max9286_priv *priv) > > i2c_mux_mask |= BIT(id); > } > - of_node_put(node); > of_node_put(i2c_mux); > > /* Parse the endpoints */ > @@ -1514,7 +1513,6 @@ static int max9286_parse_dt(struct max9286_priv *priv) > priv->source_mask |= BIT(ep.port); > priv->nsources++; > } > - of_node_put(node); > > of_property_read_u32(dev->of_node, "maxim,bus-width", &priv->bus_width); > switch (priv->bus_width) {
diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c index 20e7c7cf5eeb..f27a69b1b727 100644 --- a/drivers/media/i2c/max9286.c +++ b/drivers/media/i2c/max9286.c @@ -1450,7 +1450,6 @@ static int max9286_parse_dt(struct max9286_priv *priv) i2c_mux_mask |= BIT(id); } - of_node_put(node); of_node_put(i2c_mux); /* Parse the endpoints */ @@ -1514,7 +1513,6 @@ static int max9286_parse_dt(struct max9286_priv *priv) priv->source_mask |= BIT(ep.port); priv->nsources++; } - of_node_put(node); of_property_read_u32(dev->of_node, "maxim,bus-width", &priv->bus_width); switch (priv->bus_width) {
This is odd to have a of_node_put() just after a for_each_child_of_node() or a for_each_endpoint_of_node() loop. It should already be called during the last iteration. Remove these calls. Fixes: 66d8c9d2422d ("media: i2c: Add MAX9286 driver") Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> --- /!\ This patch is speculative, review with case /!\ --- drivers/media/i2c/max9286.c | 2 -- 1 file changed, 2 deletions(-)