PM / domains: Fix up domain-idle-states OF parsing

Web:        https://git.kernel.org/torvalds/c/a3381e3a65cbaf612c8f584906c4dba27e84267c
Commit:     a3381e3a65cbaf612c8f584906c4dba27e84267c
Parent:     7f3fdd40a7dfaa7405185250974b0fabd08c1f8b
Refname:    refs/heads/master
Author:     Ulf Hansson <[email protected]>
AuthorDate: Tue Jan 23 21:43:08 2018 +0100
Committer:  Rafael J. Wysocki <[email protected]>
CommitDate: Wed Feb 7 12:02:01 2018 +0100

    PM / domains: Fix up domain-idle-states OF parsing
    
    Commit b539cc82d493 (PM / Domains: Ignore domain-idle-states that are
    not compatible), made it possible to ignore non-compatible
    domain-idle-states OF nodes. However, in case that happens while doing
    the OF parsing, the number of elements in the allocated array would
    exceed the numbers actually needed, thus wasting memory.
    
    Fix this by pre-iterating the genpd OF node and counting the number of
    compatible domain-idle-states nodes, before doing the allocation. While
    doing this, it makes sense to rework the code a bit to avoid open coding,
    of parts responsible for the OF node iteration.
    
    Let's also take the opportunity to clarify the function header for
    of_genpd_parse_idle_states(), about what is being returned in case of
    errors.
    
    Fixes: b539cc82d493 (PM / Domains: Ignore domain-idle-states that are not compatible)
    Signed-off-by: Ulf Hansson <[email protected]>
    Reviewed-by: Lina Iyer <[email protected]>
    Signed-off-by: Rafael J. Wysocki <[email protected]>
---
 drivers/base/power/domain.c | 76 +++++++++++++++++++++++++++------------------
 1 file changed, 45 insertions(+), 31 deletions(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 528b24149bc7..1ea0e2502e8e 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -2290,6 +2290,38 @@ static int genpd_parse_state(struct genpd_power_state *genpd_state,
 	return 0;
 }
 
+static int genpd_iterate_idle_states(struct device_node *dn,
+				     struct genpd_power_state *states)
+{
+	int ret;
+	struct of_phandle_iterator it;
+	struct device_node *np;
+	int i = 0;
+
+	ret = of_count_phandle_with_args(dn, "domain-idle-states", NULL);
+	if (ret <= 0)
+		return ret;
+
+	/* Loop over the phandles until all the requested entry is found */
+	of_for_each_phandle(&it, ret, dn, "domain-idle-states", NULL, 0) {
+		np = it.node;
+		if (!of_match_node(idle_state_match, np))
+			continue;
+		if (states) {
+			ret = genpd_parse_state(&states[i], np);
+			if (ret) {
+				pr_err("Parsing idle state node %pOF failed with err %d\n",
+				       np, ret);
+				of_node_put(np);
+				return ret;
+			}
+		}
+		i++;
+	}
+
+	return i;
+}
+
 /**
  * of_genpd_parse_idle_states: Return array of idle states for the genpd.
  *
@@ -2299,49 +2331,31 @@ static int genpd_parse_state(struct genpd_power_state *genpd_state,
  *
  * Returns the device states parsed from the OF node. The memory for the states
  * is allocated by this function and is the responsibility of the caller to
- * free the memory after use.
+ * free the memory after use. If no domain idle states is found it returns
+ * -EINVAL and in case of errors, a negative error code.
  */
 int of_genpd_parse_idle_states(struct device_node *dn,
 			struct genpd_power_state **states, int *n)
 {
 	struct genpd_power_state *st;
-	struct device_node *np;
-	int i = 0;
-	int err, ret;
-	int count;
-	struct of_phandle_iterator it;
-	const struct of_device_id *match_id;
+	int ret;
 
-	count = of_count_phandle_with_args(dn, "domain-idle-states", NULL);
-	if (count <= 0)
-		return -EINVAL;
+	ret = genpd_iterate_idle_states(dn, NULL);
+	if (ret <= 0)
+		return ret < 0 ? ret : -EINVAL;
 
-	st = kcalloc(count, sizeof(*st), GFP_KERNEL);
+	st = kcalloc(ret, sizeof(*st), GFP_KERNEL);
 	if (!st)
 		return -ENOMEM;
 
-	/* Loop over the phandles until all the requested entry is found */
-	of_for_each_phandle(&it, err, dn, "domain-idle-states", NULL, 0) {
-		np = it.node;
-		match_id = of_match_node(idle_state_match, np);
-		if (!match_id)
-			continue;
-		ret = genpd_parse_state(&st[i++], np);
-		if (ret) {
-			pr_err
-			("Parsing idle state node %pOF failed with err %d\n",
-							np, ret);
-			of_node_put(np);
-			kfree(st);
-			return ret;
-		}
+	ret = genpd_iterate_idle_states(dn, st);
+	if (ret <= 0) {
+		kfree(st);
+		return ret < 0 ? ret : -EINVAL;
 	}
 
-	*n = i;
-	if (!i)
-		kfree(st);
-	else
-		*states = st;
+	*states = st;
+	*n = ret;
 
 	return 0;
 }
--
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