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Message-ID: <1347030721.13424.22.camel@joe2Laptop>
Subject: Re: [PATCH 0/5] dev_<level> and dynamic_debug cleanups
From: Joe Perches <joe@perches.com>
To: Jason Baron <jbaron@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, netdev@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jim Cromie <jim.cromie@gmail.com>, Kay Sievers <kay@vrfy.org>,
        linux-kernel@vger.kernel.org
Date: Fri, 07 Sep 2012 08:12:01 -0700
In-Reply-To: <20120907145235.GA18673@redhat.com>
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On Fri, 2012-09-07 at 10:52 -0400, Jason Baron wrote:
> On Thu, Sep 06, 2012 at 11:43:46AM -0700, Joe Perches wrote:
> > On Thu, 2012-09-06 at 13:51 -0400, Jason Baron wrote:
> > > On Sun, Aug 26, 2012 at 04:25:25AM -0700, Joe Perches wrote:
> > > > The recent commit to fix dynamic_debug was a bit unclean.
> > > > Neaten the style for dynamic_debug.
> > > > Reduce the stack use of message logging that uses netdev_printk
> > > > Add utility functions dev_printk_emit and dev_vprintk_emit for /dev/kmsg.
> > > > 
> > > > Joe Perches (5):
> > > >   dev_dbg/dynamic_debug: Update to use printk_emit, optimize stack
> > > >   netdev_printk/dynamic_netdev_dbg: Directly call printk_emit
> > > >   netdev_printk/netif_printk: Remove a superfluous logging colon
> > > >   dev: Add dev_vprintk_emit and dev_printk_emit
> > > >   device and dynamic_debug: Use dev_vprintk_emit and dev_printk_emit
> > > > 
> > > 
> > > Looks Good.
> > > 
> > > The one thing that is bothering me though, is that for
> > > __dynamic_dev_dbg(), __dynamic_netdev_dbg(), we are copying much of the core
> > > logic of __dev_printk(), __netdev_printk(), respectively. I would prefer
> > > have this in one place. Can we add a 'prefix' argument to __dev_printk(),
> > > and __netdev_printk() that dynamic debug can use, but is simply empty
> > > for dev_printk() and netdev_printk().
> > 
> > I don't think that's an improvement actually.
> > Why don't you try it.
> > 
> 
> Ok, below is what I was thinking. It winds up being more deletions than
> insertions.
> 
> Thanks,
> 
> -Jason
> 
> dynamic debug: remove duplicate __netdev_printk() and  __dev_printk() logic 
> 
> Add an option prefix string argument to __netdev_printk() and __dev_printk().
> In this way dynamic debug does not have to contain duplicate logic.
> 
> Signed-off-by: Jason Baron <jbaron@redhat.com>
> ---
>  drivers/base/core.c       |   13 +++++++------
>  include/linux/device.h    |    3 +++
>  include/linux/netdevice.h |    3 +++
>  lib/dynamic_debug.c       |   32 ++++++++------------------------
>  net/core/dev.c            |   11 ++++++-----
>  5 files changed, 27 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 65f82e3..7b4ee6d 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1937,15 +1937,16 @@ int dev_printk_emit(int level, const struct device *dev, const char *fmt, ...)
>  }
>  EXPORT_SYMBOL(dev_printk_emit);
>  
> -static int __dev_printk(const char *level, const struct device *dev,
> -			struct va_format *vaf)
> +int __dev_printk(const char *level, const struct device *dev,
> +		 char *prefix, struct va_format *vaf)
>  {
>  	if (!dev)
>  		return printk("%s(NULL device *): %pV", level, vaf);
>  
>  	return dev_printk_emit(level[1] - '0', dev,
> -			       "%s %s: %pV",
> -			       dev_driver_string(dev), dev_name(dev), vaf);
> +			       "%s%s %s: %pV",
> +			       prefix, dev_driver_string(dev),
> +			       dev_name(dev), vaf);
>  }
>  
>  int dev_printk(const char *level, const struct device *dev,
> @@ -1960,7 +1961,7 @@ int dev_printk(const char *level, const struct device *dev,
>  	vaf.fmt = fmt;
>  	vaf.va = &args;
>  
> -	r = __dev_printk(level, dev, &vaf);
> +	r = __dev_printk(level, dev, "", &vaf);
>  
>  	va_end(args);
>  
> @@ -1980,7 +1981,7 @@ int func(const struct device *dev, const char *fmt, ...)	\
>  	vaf.fmt = fmt;						\
>  	vaf.va = &args;						\
>  								\
> -	r = __dev_printk(kern_level, dev, &vaf);		\
> +	r = __dev_printk(kern_level, dev, "", &vaf);		\
>  								\
>  	va_end(args);						\
>  								\
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 2da4589..573b15e 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -891,6 +891,9 @@ extern const char *dev_driver_string(const struct device *dev);
>  
>  #ifdef CONFIG_PRINTK
>  
> +extern int __dev_printk(const char *level, const struct device *dev,
> +			char *prefix, struct va_format *vaf);
> +
>  extern int dev_vprintk_emit(int level, const struct device *dev,
>  			    const char *fmt, va_list args);
>  extern __printf(3, 4)
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 5f49cc0..63f6165 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -2720,6 +2720,9 @@ static inline const char *netdev_name(const struct net_device *dev)
>  	return dev->name;
>  }
>  
> +extern int __netdev_printk(const char *level, const struct net_device *dev,
> +			   char *prefix, struct va_format *vaf);
> +
>  extern __printf(3, 4)
>  int netdev_printk(const char *level, const struct net_device *dev,
>  		  const char *format, ...);
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index e7f7d99..83bf601 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -578,6 +578,7 @@ int __dynamic_dev_dbg(struct _ddebug *descriptor,
>  	struct va_format vaf;
>  	va_list args;
>  	int res;
> +	char buf[PREFIX_SIZE];
>  
>  	BUG_ON(!descriptor);
>  	BUG_ON(!fmt);
> @@ -587,16 +588,9 @@ int __dynamic_dev_dbg(struct _ddebug *descriptor,
>  	vaf.fmt = fmt;
>  	vaf.va = &args;
>  
> -	if (!dev) {
> -		res = printk(KERN_DEBUG "(NULL device *): %pV", &vaf);
> -	} else {
> -		char buf[PREFIX_SIZE];
> -
> -		res = dev_printk_emit(7, dev, "%s%s %s: %pV",
> -				      dynamic_emit_prefix(descriptor, buf),
> -				      dev_driver_string(dev), dev_name(dev),
> -				      &vaf);
> -	}
> +	res = __dev_printk(KERN_DEBUG, dev,
> +			   dynamic_emit_prefix(descriptor, buf),
> +			   &vaf);
>  
>  	va_end(args);
>  
> @@ -612,6 +606,7 @@ int __dynamic_netdev_dbg(struct _ddebug *descriptor,
>  	struct va_format vaf;
>  	va_list args;
>  	int res;
> +	char buf[PREFIX_SIZE];
>  
>  	BUG_ON(!descriptor);
>  	BUG_ON(!fmt);
> @@ -621,20 +616,9 @@ int __dynamic_netdev_dbg(struct _ddebug *descriptor,
>  	vaf.fmt = fmt;
>  	vaf.va = &args;
>  
> -	if (dev && dev->dev.parent) {
> -		char buf[PREFIX_SIZE];
> -
> -		res = dev_printk_emit(7, dev->dev.parent,
> -				      "%s%s %s %s: %pV",
> -				      dynamic_emit_prefix(descriptor, buf),
> -				      dev_driver_string(dev->dev.parent),
> -				      dev_name(dev->dev.parent),
> -				      netdev_name(dev), &vaf);
> -	} else if (dev) {
> -		res = printk(KERN_DEBUG "%s: %pV", netdev_name(dev), &vaf);
> -	} else {
> -		res = printk(KERN_DEBUG "(NULL net_device): %pV", &vaf);
> -	}
> +	res = __netdev_printk(KERN_DEBUG, dev,
> +			      dynamic_emit_prefix(descriptor, buf),
> +			      &vaf);
>  
>  	va_end(args);
>  
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 8ad42fd..5fef0f6 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -6422,15 +6422,16 @@ const char *netdev_drivername(const struct net_device *dev)
>  	return empty;
>  }
>  
> -static int __netdev_printk(const char *level, const struct net_device *dev,
> -			   struct va_format *vaf)
> +int __netdev_printk(const char *level, const struct net_device *dev,
> +		    char *prefix, struct va_format *vaf)
>  {
>  	int r;
>  
>  	if (dev && dev->dev.parent) {
>  		r = dev_printk_emit(level[1] - '0',
>  				    dev->dev.parent,
> -				    "%s %s %s: %pV",
> +				    "%s%s %s %s: %pV",
> +				    prefix,
>  				    dev_driver_string(dev->dev.parent),
>  				    dev_name(dev->dev.parent),
>  				    netdev_name(dev), vaf);
> @@ -6455,7 +6456,7 @@ int netdev_printk(const char *level, const struct net_device *dev,
>  	vaf.fmt = format;
>  	vaf.va = &args;
>  
> -	r = __netdev_printk(level, dev, &vaf);
> +	r = __netdev_printk(level, dev, "", &vaf);
>  
>  	va_end(args);
>  
> @@ -6475,7 +6476,7 @@ int func(const struct net_device *dev, const char *fmt, ...)	\
>  	vaf.fmt = fmt;						\
>  	vaf.va = &args;						\
>  								\
> -	r = __netdev_printk(level, dev, &vaf);			\
> +	r = __netdev_printk(level, dev, "", &vaf);		\
>  								\
>  	va_end(args);						\
>  								\

'Morning Jason.

Funny.  Crossed emails.

I still don't think this is better.

This does add an effectively unused "" to non-dynamic debug builds.
ie: the more common paths are encumbered as dynamic_debug isn't
a normally enabled distribution CONFIG_ option.

About the patch:

Wouldn't dev_printk_emit now would have a single caller and
could be made static?

Don't __dev_printk and __netdev_printk need EXPORT_SYMBOLs?

cheers, Joe