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Date: Fri, 7 Sep 2012 11:35:42 -0400
From: Jason Baron <jbaron@...hat.com>
To: Joe Perches <joe@...ches.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, netdev@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"David S. Miller" <davem@...emloft.net>,
Jim Cromie <jim.cromie@...il.com>, Kay Sievers <kay@...y.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/5] dev_<level> and dynamic_debug cleanups
On Fri, Sep 07, 2012 at 08:12:01AM -0700, Joe Perches wrote:
> 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@...hat.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.
Yeah, not sure - I know Fedora enables it.
>
> About the patch:
>
> Wouldn't dev_printk_emit now would have a single caller and
> could be made static?
>
Yes, I believe so.
> Don't __dev_printk and __netdev_printk need EXPORT_SYMBOLs?
>
The usage in lib/dynamic_debug.c can't be built as a module. So not required.
If nobody else thinks this patch is better, let's at least add a comment in
__dev_printk() and __netdev_printk() to fix dynamic debug, if these are changed.
Thanks,
-Jason
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