diff mbox

[v2,1/4] clk: add common __clk_get(), __clk_put() implementations

Message ID 1377020063-30213-2-git-send-email-s.nawrocki@samsung.com (mailing list archive)
State New, archived
Headers show

Commit Message

Sylwester Nawrocki/Kernel \(PLT\) /SRPOL/Staff Engineer/Samsung Electronics Aug. 20, 2013, 5:34 p.m. UTC 
This patch adds common __clk_get(), __clk_put() clkdev helpers which
replace their platform specific counterparts when the common clock
API is enabled.

The owner module pointer field is added to struct clk so a reference
to the clock supplier module can be taken by the clock consumers.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---

No changes since previous version.

 arch/arm/include/asm/clkdev.h      |    2 ++
 arch/blackfin/include/asm/clkdev.h |    2 ++
 arch/mips/include/asm/clkdev.h     |    2 ++
 arch/sh/include/asm/clkdev.h       |    2 ++
 drivers/clk/clk.c                  |   24 ++++++++++++++++++++++++
 include/linux/clk-private.h        |    3 +++
 include/linux/clkdev.h             |    5 +++++
 7 files changed, 40 insertions(+)

--
1.7.9.5

Comments

Russell King - ARM Linux Aug. 20, 2013, 8:30 p.m. UTC | #1 
On Tue, Aug 20, 2013 at 07:34:20PM +0200, Sylwester Nawrocki wrote:
> +int __clk_get(struct clk *clk)
> +{
> +	if (WARN_ON((!clk)))
> +		return 0;

This changes the behaviour of clk_get()

> +
> +	if (!try_module_get(clk->owner))
> +		return 0;

If you want this to be safe against NULL pointers, just do this:

	if (clk && !try_module_get(clk->owner))
		return 0;

> +
> +	return 1;
> +}
> +EXPORT_SYMBOL(__clk_get);
> +
> +void __clk_put(struct clk *clk)
> +{
> +	if (!clk || IS_ERR(clk))
> +		return;
> +
> +	module_put(clk->owner);

Calling clk_put() with an error-pointer should be a Bad Thing and something
that shouldn't be encouraged, so trapping it is probably unwise.  So, just
do here:

	if (clk)
		module_put(clk->owner);

If we do have some callers of this with ERR pointers, then we could add:

	if (WARN_ON_ONCE(IS_ERR(clk)))
		return;

and remove it after a full kernel cycle or so.
Sylwester Nawrocki/Kernel \(PLT\) /SRPOL/Staff Engineer/Samsung Electronics Aug. 23, 2013, 2:41 p.m. UTC | #2 
On 08/20/2013 10:30 PM, Russell King - ARM Linux wrote:
> On Tue, Aug 20, 2013 at 07:34:20PM +0200, Sylwester Nawrocki wrote:
>> +int __clk_get(struct clk *clk)
>> +{
>> +	if (WARN_ON((!clk)))
>> +		return 0;
> 
> This changes the behaviour of clk_get()

My bad, will remove that.

>> +
>> +	if (!try_module_get(clk->owner))
>> +		return 0;
> 
> If you want this to be safe against NULL pointers, just do this:
> 
> 	if (clk && !try_module_get(clk->owner))
> 		return 0;

Ok, that should work too.

>> +
>> +	return 1;
>> +}
>> +EXPORT_SYMBOL(__clk_get);
>> +
>> +void __clk_put(struct clk *clk)
>> +{
>> +	if (!clk || IS_ERR(clk))
>> +		return;
>> +
>> +	module_put(clk->owner);
> 
> Calling clk_put() with an error-pointer should be a Bad Thing and something
> that shouldn't be encouraged, so trapping it is probably unwise.  So, just
> do here:
> 
> 	if (clk)
> 		module_put(clk->owner);
> 
> If we do have some callers of this with ERR pointers, then we could add:
> 
> 	if (WARN_ON_ONCE(IS_ERR(clk)))
> 		return;
> 
> and remove it after a full kernel cycle or so.

I wouldn't be surprised to see some callers with ERR pointers, since
clk_put() has been mostly a no op. I'm inclined to leave such a check
temporarily, let's see if it catches any issues.

Thanks for review of the other patches.
diff mbox

Patch

diff --git a/arch/arm/include/asm/clkdev.h b/arch/arm/include/asm/clkdev.h
index 80751c1..4e8a4b2 100644
--- a/arch/arm/include/asm/clkdev.h
+++ b/arch/arm/include/asm/clkdev.h
@@ -14,12 +14,14 @@ 

 #include <linux/slab.h>

+#ifndef CONFIG_COMMON_CLK
 #ifdef CONFIG_HAVE_MACH_CLKDEV
 #include <mach/clkdev.h>
 #else
 #define __clk_get(clk)	({ 1; })
 #define __clk_put(clk)	do { } while (0)
 #endif
+#endif

 static inline struct clk_lookup_alloc *__clkdev_alloc(size_t size)
 {
diff --git a/arch/blackfin/include/asm/clkdev.h b/arch/blackfin/include/asm/clkdev.h
index 9053bed..7ac2436 100644
--- a/arch/blackfin/include/asm/clkdev.h
+++ b/arch/blackfin/include/asm/clkdev.h
@@ -8,7 +8,9 @@  static inline struct clk_lookup_alloc *__clkdev_alloc(size_t size)
 	return kzalloc(size, GFP_KERNEL);
 }

+#ifndef CONFIG_COMMON_CLK
 #define __clk_put(clk)
 #define __clk_get(clk) ({ 1; })
+#endif

 #endif
diff --git a/arch/mips/include/asm/clkdev.h b/arch/mips/include/asm/clkdev.h
index 2624754..1b3ad7b 100644
--- a/arch/mips/include/asm/clkdev.h
+++ b/arch/mips/include/asm/clkdev.h
@@ -14,8 +14,10 @@ 

 #include <linux/slab.h>

+#ifndef CONFIG_COMMON_CLK
 #define __clk_get(clk)	({ 1; })
 #define __clk_put(clk)	do { } while (0)
+#endif

 static inline struct clk_lookup_alloc *__clkdev_alloc(size_t size)
 {
diff --git a/arch/sh/include/asm/clkdev.h b/arch/sh/include/asm/clkdev.h
index 6ba9186..c419014 100644
--- a/arch/sh/include/asm/clkdev.h
+++ b/arch/sh/include/asm/clkdev.h
@@ -25,7 +25,9 @@  static inline struct clk_lookup_alloc *__clkdev_alloc(size_t size)
 		return kzalloc(size, GFP_KERNEL);
 }

+#ifndef CONFIG_COMMON_CLK
 #define __clk_put(clk)
 #define __clk_get(clk) ({ 1; })
+#endif

 #endif /* __CLKDEV_H__ */
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 56a00db..0e0eb31 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1851,6 +1851,30 @@  void devm_clk_unregister(struct device *dev, struct clk *clk)
 }
 EXPORT_SYMBOL_GPL(devm_clk_unregister);

+/*
+ * clkdev helpers
+ */
+int __clk_get(struct clk *clk)
+{
+	if (WARN_ON((!clk)))
+		return 0;
+
+	if (!try_module_get(clk->owner))
+		return 0;
+
+	return 1;
+}
+EXPORT_SYMBOL(__clk_get);
+
+void __clk_put(struct clk *clk)
+{
+	if (!clk || IS_ERR(clk))
+		return;
+
+	module_put(clk->owner);
+}
+EXPORT_SYMBOL(__clk_put);
+
 /***        clk rate change notifiers        ***/

 /**
diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
index dd7adff..b7c0b58 100644
--- a/include/linux/clk-private.h
+++ b/include/linux/clk-private.h
@@ -25,10 +25,13 @@ 

 #ifdef CONFIG_COMMON_CLK

+struct module;
+
 struct clk {
 	const char		*name;
 	const struct clk_ops	*ops;
 	struct clk_hw		*hw;
+	struct module		*owner;
 	struct clk		*parent;
 	const char		**parent_names;
 	struct clk		**parents;
diff --git a/include/linux/clkdev.h b/include/linux/clkdev.h
index a6a6f60..94bad77 100644
--- a/include/linux/clkdev.h
+++ b/include/linux/clkdev.h
@@ -43,4 +43,9 @@  int clk_add_alias(const char *, const char *, char *, struct device *);
 int clk_register_clkdev(struct clk *, const char *, const char *, ...);
 int clk_register_clkdevs(struct clk *, struct clk_lookup *, size_t);

+#ifdef CONFIG_COMMON_CLK
+int __clk_get(struct clk *clk);
+void __clk_put(struct clk *clk);
+#endif
+
 #endif