[PATCH net-next v2 05/10] drivers: base: Add device_find_class()

On 01/12/2017 01:21 PM, David Miller wrote:

From: Florian Fainelli <f.fainelli@gmail.com>
Date: Wed, 11 Jan 2017 19:41:16 -0800

quoted

Add a helper function to lookup a device reference given a class name.
This is a preliminary patch to remove adhoc code from net/dsa/dsa.c and
make it more generic.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/base/core.c    | 19 +++++++++++++++++++
 include/linux/device.h |  1 +
 2 files changed, 20 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 020ea7f05520..3dd6047c10d8 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c

@@ -2065,6 +2065,25 @@ struct device *device_find_child(struct device *parent, void *data,
 }
 EXPORT_SYMBOL_GPL(device_find_child);
 
+static int dev_is_class(struct device *dev, void *class)

I know you are just moving code, but this class argumnet is a string
and thus should be "char *" or even "const char *".

Well, this is really so that we don't need to cast the arguments passed
to device_find_child(), which takes a void *data as well. If we made
that a const char *class, we'd get warnings that look like these:

drivers/base/core.c: In function 'device_find_class':
drivers/base/core.c:2083:2: warning: passing argument 2 of
'device_find_child' discards 'const' qualifier from pointer target type
[enabled by default]
  return device_find_child(parent, class, dev_is_class);
  ^
drivers/base/core.c:2050:16: note: expected 'void *' but argument is of
type 'const char *'
 struct device *device_find_child(struct device *parent, void *data,
                ^
drivers/base/core.c:2083:2: warning: passing argument 3 of
'device_find_child' from incompatible pointer type [enabled by default]
  return device_find_child(parent, class, dev_is_class);
  ^
drivers/base/core.c:2050:16: note: expected 'int (*)(struct device *,
void *)' but argument is of type 'int (*)(struct device *, const char *)'
 struct device *device_find_child(struct device *parent, void *data,
                ^

-- 
Florian