| Message ID | 20170307100846.0487135b@endymion (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On 03/07/2017 01:08 AM, Jean Delvare wrote: > Hi Guenter, > > On Mon, 6 Mar 2017 15:47:55 -0800, Guenter Roeck wrote: >> On Mon, Mar 06, 2017 at 09:48:35PM +0100, Peter Hüwe wrote: >>> Hi Guenter, >>> >>> I was wondering whether there was a particular reason why >>> hwmon_attr_show_string passes only an "empty" pointer(pointer) to the ops- >>>> read_string function rather than the buffer itself? >>> >>> Wouldn't this mean that in ops->read_string I'd have to reserve some space for >>> the value on the heap (and taking care to free it somewhere, since returning >>> an address on the stack is bad idea), instead of calling sprintf(buf, "%s\n", >>> s) directly? >>> >>> With the current implementation I have to sprintf it into my local buffer and >>> you sprintf it again into the final buffer. >> >> The idea was that the called code would return a pointer to a constant string, >> ie one that isn't changing from call to call. > > In that case, what about the following change? > > Subject: hwmon: Constify str parameter of hwmon_ops->read_string > > The read_string callback is supposed to retrieve a pointer to a > constant string. > > Signed-off-by: Jean Delvare <jdelvare@suse.de> Makes sense. I'll add it to -next. Thanks, Guenter > --- > drivers/hwmon/hwmon.c | 2 +- > include/linux/hwmon.h | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > --- linux-4.10.orig/drivers/hwmon/hwmon.c 2017-02-19 23:34:00.000000000 +0100 > +++ linux-4.10/drivers/hwmon/hwmon.c 2017-03-07 08:22:27.784527968 +0100 > @@ -186,7 +186,7 @@ static ssize_t hwmon_attr_show_string(st > char *buf) > { > struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr); > - char *s; > + const char *s; > int ret; > > ret = hattr->ops->read_string(dev, hattr->type, hattr->attr, > --- linux-4.10.orig/include/linux/hwmon.h 2017-02-19 23:34:00.000000000 +0100 > +++ linux-4.10/include/linux/hwmon.h 2017-03-07 08:21:28.247998585 +0100 > @@ -336,7 +336,7 @@ struct hwmon_ops { > int (*read)(struct device *dev, enum hwmon_sensor_types type, > u32 attr, int channel, long *val); > int (*read_string)(struct device *dev, enum hwmon_sensor_types type, > - u32 attr, int channel, char **str); > + u32 attr, int channel, const char **str); > int (*write)(struct device *dev, enum hwmon_sensor_types type, > u32 attr, int channel, long val); > }; > > -- To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- linux-4.10.orig/drivers/hwmon/hwmon.c 2017-02-19 23:34:00.000000000 +0100 +++ linux-4.10/drivers/hwmon/hwmon.c 2017-03-07 08:22:27.784527968 +0100 @@ -186,7 +186,7 @@ static ssize_t hwmon_attr_show_string(st char *buf) { struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr); - char *s; + const char *s; int ret; ret = hattr->ops->read_string(dev, hattr->type, hattr->attr, --- linux-4.10.orig/include/linux/hwmon.h 2017-02-19 23:34:00.000000000 +0100 +++ linux-4.10/include/linux/hwmon.h 2017-03-07 08:21:28.247998585 +0100 @@ -336,7 +336,7 @@ struct hwmon_ops { int (*read)(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long *val); int (*read_string)(struct device *dev, enum hwmon_sensor_types type, - u32 attr, int channel, char **str); + u32 attr, int channel, const char **str); int (*write)(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long val); };