[PATCH v2 0/3] powerpc/kernel: Simplify rtas_initialize()

[PATCH v2 0/3] powerpc/kernel: Simplify rtas_initialize()

[Gavin Shan]

This simplifies rtas_initialize(), no functional changes introduced:

   * PATCH[1/3] removes the unnecessary nested if statements.
   * PATCH[2/3] uses of_property_read_u32() instead of converting the
     property's data to target in CPU endian.
   * PATCH[3/3] decreases RTAS device-tree node's refcount in error path.

v2:
   * Set RTAS device-tree node to NULL if its base, or size, or both of
     them can't be found.

Gavin Shan (3):
  powerpc/kernel: Remove nested if statements in rtas_initialize()
  powerpc/kernel: Use of_property_read_u32() in rtas_initialize()
  powerpc/kernel: Fix unbalanced refcount on RTAS device node

 arch/powerpc/kernel/rtas.c | 32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

-- 
2.7.4

[PATCH v2 1/3] powerpc/kernel: Remove nested if statements in rtas_initialize()

[Gavin Shan]

This removes the unnecessary nested if statements in function
rtas_initialize(), to simplify the code. No functional changes
introduced.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
---
v2: Set device node to NULL when base or size isn't found
---
 arch/powerpc/kernel/rtas.c | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 112cc3b..9759dcb 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -1145,31 +1145,30 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs)
 void __init rtas_initialize(void)
 {
 	unsigned long rtas_region = RTAS_INSTANTIATE_MAX;
+	const __be32 *basep, *entryp, *sizep;
 
 	/* Get RTAS dev node and fill up our "rtas" structure with infos
 	 * about it.
 	 */
 	rtas.dev = of_find_node_by_name(NULL, "rtas");
-	if (rtas.dev) {
-		const __be32 *basep, *entryp, *sizep;
-
-		basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
-		sizep = of_get_property(rtas.dev, "rtas-size", NULL);
-		if (basep != NULL && sizep != NULL) {
-			rtas.base = __be32_to_cpu(*basep);
-			rtas.size = __be32_to_cpu(*sizep);
-			entryp = of_get_property(rtas.dev,
-					"linux,rtas-entry", NULL);
-			if (entryp == NULL) /* Ugh */
-				rtas.entry = rtas.base;
-			else
-				rtas.entry = __be32_to_cpu(*entryp);
-		} else
-			rtas.dev = NULL;
-	}
 	if (!rtas.dev)
 		return;
 
+	basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
+	sizep = of_get_property(rtas.dev, "rtas-size", NULL);
+	if (basep == NULL || sizep == NULL) {
+		rtas.dev = NULL;
+		return;
+	}
+
+	rtas.base = __be32_to_cpu(*basep);
+	rtas.size = __be32_to_cpu(*sizep);
+	entryp = of_get_property(rtas.dev, "linux,rtas-entry", NULL);
+	if (entryp == NULL) /* Ugh */
+		rtas.entry = rtas.base;
+	else
+		rtas.entry = __be32_to_cpu(*entryp);
+
 	/* If RTAS was found, allocate the RMO buffer for it and look for
 	 * the stop-self token if any
 	 */
-- 
2.7.4

[PATCH v2 2/3] powerpc/kernel: Use of_property_read_u32() in rtas_initialize()

[Gavin Shan]

This uses of_property_read_u32() in rtas_initialize() so that we
needn't explicitly care the CPU's endian.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/rtas.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 9759dcb..ba5a4cc 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -1145,7 +1145,8 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs)
 void __init rtas_initialize(void)
 {
 	unsigned long rtas_region = RTAS_INSTANTIATE_MAX;
-	const __be32 *basep, *entryp, *sizep;
+	u32 base, size, entry;
+	int no_base, no_size, no_entry;
 
 	/* Get RTAS dev node and fill up our "rtas" structure with infos
 	 * about it.
@@ -1154,20 +1155,17 @@ void __init rtas_initialize(void)
 	if (!rtas.dev)
 		return;
 
-	basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
-	sizep = of_get_property(rtas.dev, "rtas-size", NULL);
-	if (basep == NULL || sizep == NULL) {
+	no_base = of_property_read_u32(rtas.dev, "linux,rtas-base", &base);
+	no_size = of_property_read_u32(rtas.dev, "rtas-size", &size);
+	if (no_base || no_size) {
 		rtas.dev = NULL;
 		return;
 	}
 
-	rtas.base = __be32_to_cpu(*basep);
-	rtas.size = __be32_to_cpu(*sizep);
-	entryp = of_get_property(rtas.dev, "linux,rtas-entry", NULL);
-	if (entryp == NULL) /* Ugh */
-		rtas.entry = rtas.base;
-	else
-		rtas.entry = __be32_to_cpu(*entryp);
+	rtas.base = base;
+	rtas.size = size;
+	no_entry = of_property_read_u32(rtas.dev, "linux,rtas-entry", &entry);
+	rtas.entry = no_entry ? rtas.base : entry;
 
 	/* If RTAS was found, allocate the RMO buffer for it and look for
 	 * the stop-self token if any
-- 
2.7.4

[PATCH v2 3/3] powerpc/kernel: Fix unbalanced refcount on RTAS device node

[Gavin Shan]

The RTAS device-tree node's refcount has been increased by one in
the function call of_find_node_by_name(), but it's missed to be
decreased by one in the error path. It leads to unbalanced refcount
on RTAS device-tree node.

This fixes above issue by decreasing RTAS device-tree node's refcount
in error path.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/rtas.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index ba5a4cc..b8a4987 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -1158,6 +1158,7 @@ void __init rtas_initialize(void)
 	no_base = of_property_read_u32(rtas.dev, "linux,rtas-base", &base);
 	no_size = of_property_read_u32(rtas.dev, "rtas-size", &size);
 	if (no_base || no_size) {
+		of_node_put(rtas.dev);
 		rtas.dev = NULL;
 		return;
 	}
-- 
2.7.4

Re: [v2, 1/3] powerpc/kernel: Remove nested if statements in rtas_initialize()

[Michael Ellerman]

On Mon, 2017-01-23 at 22:49:52 UTC, Gavin Shan wrote:
> This removes the unnecessary nested if statements in function
> rtas_initialize(), to simplify the code. No functional changes
> introduced.
> 
> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/dbecd5093043faa9da83c720ed0e08

cheers