Re: [PATCH 0/5] dev_<level> and dynamic_debug cleanups

From: Joe Perches
Date: Fri Sep 07 2012 - 11:11:59 EST

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@xxxxxxxxxx>
> ---
> 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

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