Re: [dpdk-dev] [PATCH v2] net/ixgbe: clean up rte_eth_dev_info_get

[Tiwei Bie <tiwei.bie@intel.com>]

On Mon, Feb 06, 2017 at 11:45:41AM +0800, Lu, Wenzhuo wrote:
> Hi Tiwei,
> 
> > -----Original Message-----
> > From: Bie, Tiwei
> > Sent: Monday, February 6, 2017 11:08 AM
> > To: Lu, Wenzhuo
> > Cc: dev@dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH v2] net/ixgbe: clean up rte_eth_dev_info_get
> > 
> > On Mon, Feb 06, 2017 at 10:59:42AM +0800, Lu, Wenzhuo wrote:
> > > Hi Tiwei,
> > >
> > >
> > > > -----Original Message-----
> > > > From: Bie, Tiwei
> > > > Sent: Monday, February 6, 2017 10:51 AM
> > > > To: Lu, Wenzhuo
> > > > Cc: dev@dpdk.org
> > > > Subject: Re: [dpdk-dev] [PATCH v2] net/ixgbe: clean up
> > > > rte_eth_dev_info_get
> > > >
> > > > On Mon, Feb 06, 2017 at 10:41:28AM +0800, Lu, Wenzhuo wrote:
> > > > > Hi Tiwei,
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Bie, Tiwei
> > > > > > Sent: Monday, February 6, 2017 10:31 AM
> > > > > > To: Lu, Wenzhuo
> > > > > > Cc: dev@dpdk.org
> > > > > > Subject: Re: [dpdk-dev] [PATCH v2] net/ixgbe: clean up
> > > > > > rte_eth_dev_info_get
> > > > > >
> > > > > > On Mon, Feb 06, 2017 at 10:09:32AM +0800, Wenzhuo Lu wrote:
> > > > > > [...]
> > > > > > >  static void ixgbe_dcb_init(struct ixgbe_hw *hw, struct
> > > > > > > ixgbe_dcb_config *dcb_config); -static int is_ixgbe_pmd(const
> > > > > > > char *driver_name);
> > > > > > > +static int is_device_supported(struct rte_eth_dev *dev,
> > > > > > > +struct eth_driver *drv);
> > > > > > >
> > > > > >
> > > > > > Should be:
> > > > > > static bool is_device_supported(struct rte_eth_dev *dev, struct
> > > > > > eth_driver *drv);
> > > > > O, forget to change it. Thanks.
> > > > >
> > > > > >
> > > > > > >  /* For Virtual Function support */  static int
> > > > > > > eth_ixgbevf_dev_init(struct rte_eth_dev *eth_dev); @@
> > > > > > > -4380,16 +4380,14 @@ static int
> > > > > > ixgbevf_dev_xstats_get_names(__rte_unused struct rte_eth_dev
> > > > > > *dev,
> > > > > > >  	ixgbe_add_rar(dev, addr, 0, 0);  }
> > > > > > >
> > > > > > > -static int
> > > > > > > -is_ixgbe_pmd(const char *driver_name)
> > > > > > > +static bool
> > > > > > > +is_device_supported(struct rte_eth_dev *dev, struct
> > > > > > > +eth_driver
> > > > > > > +*drv)
> > > > > > >  {
> > > > > > > -	if (!strstr(driver_name, "ixgbe"))
> > > > > > > -		return -ENOTSUP;
> > > > > > > +	if (strcmp(dev->driver->pci_drv.driver.name,
> > > > > > > +		   drv->pci_drv.driver.name))
> > > > > > > +		return FALSE;
> > > > > > >
> > > > > >
> > > > > > It would be better to use `false' instead of `FALSE'.
> > > > > I see both 'false' and 'FALSE' are defined and used. Is there any
> > > > > reason that
> > > > 'false' is better?
> > > > >
> > > >
> > > > I think `true' and `false' are standard keywords defined and
> > > > reserved by C. So I think it would be better to use them if the return type is
> > `bool'.
> > > O, there's no 'bool' in C. You have to define it. The same for 'false' and 'true'.
> > >
> > 
> > The `bool', `true' and `false' are all standard keywords defined and reserved by
> > C, although the stdbool.h is not used in ixgbe.
> > 
> > C adds this support by introducing a new header stdbool.h:
> > 
> > #ifndef __bool_true_false_are_defined
> > #define __bool_true_false_are_defined   1
> > 
> > #ifndef __cplusplus
> > 
> > #define false   0
> > #define true    1
> > 
> > #define bool    _Bool
> > #if __STDC_VERSION__ < 199901L && __GNUC__ < 3
> > && !defined(__INTEL_COMPILER)
> > typedef int     _Bool;
> > #endif
> O, you're talking about C99. _Bool is a  keyword added by it. 'bool', 'true', 'false' are  not. That's why this header file have to define them.
> 

C99 added all those as keyword, although doesn't implement
all of them as the builtin type (e.g. int). All of them are
standard keywords defined by C99. The `bool', `true' and
`false' are defined in section 7.16 of the C99 spec [1] and
implemented as macros:

7.16 Boolean type and values <stdbool.h>

1 The header <stdbool.h> defines four macros.

2 The macro
          bool
expands to _Bool.

3 The remaining three macros are suitable for use in #if preprocessing directives. They are
          true
which expands to the integer constant 1,
          false
which expands to the integer constant 0, and
          __bool_true_false_are_defined
which expands to the integer constant 1.

4 Notwithstanding the provisions of 7.1.3, a program may undefine and perhaps then redefine the macros bool, true, and false.222)

Footnotes

222) See ''future library directions'' (7.26.7).

[1] http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf

Best regards,
Tiwei Bie