linux-kernel - Re: [PATCH 0/3] dynamic_hex

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Message-ID: <1493418714.1873.18.camel@perches.com>
Date:   Fri, 28 Apr 2017 15:31:54 -0700
From:   Joe Perches <joe@...ches.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        linux-remoteproc@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        Jason Baron <jbaron@...mai.com>
Subject: Re: [PATCH 0/3] dynamic_hex_dump cleanup

On Fri, 2017-04-28 at 15:19 -0700, Dan Williams wrote:
> On Fri, Apr 28, 2017 at 3:14 PM, Dan Williams <dan.j.williams@...el.com> wrote:
> > On Fri, Apr 28, 2017 at 3:07 PM, Joe Perches <joe@...ches.com> wrote:
> > > On Fri, 2017-04-28 at 14:52 -0700, Dan Williams wrote:
> > > > On Fri, Apr 28, 2017 at 2:49 PM, Joe Perches <joe@...ches.com> wrote:
> > > > > On Fri, 2017-04-28 at 14:28 -0700, Dan Williams wrote:
> > > > > > More than one driver has worked around the fact that
> > > > > > print_hex_dump_debug() requires CONFIG_DYNAMIC_DEBUG=y to build.
> > > > > 
> > > > > No it doesn't.  builds work fine.  Output is restricted.
> > > > > 
> > > > > > Provide a dynamic_hex_dump() so that drivers that want the extra debugging to be
> > > > > > turned off in the CONFIG_DYNAMIC_DEBUG=n can use dynamic_hex_dump()
> > > > > > directly.
> > > > > 
> > > > > I think the concept is unnecessary
> > > > > .
> > > > > Just use print_hex_dump with KERN_DEBUG.
> > > > 
> > > > No, we don't want any possibility of output in the
> > > > CONFIG_DYNAMIC_DEBUG=n case. This is extra debug that only makes sense
> > > > in the CONFIG_DYNAMIC_DEBUG case.
> > > 
> > > No, that doesn't work the same.
> > > 
> > > Look at your conversion of drivers/acpi/nfit/core.c
> > > 
> > > dev_dbg outputs always when DEBUG is defined and
> > > optionally outputs when CONFIG_DYNAMIC_DEBUG is enabled.
> > 
> > Right, that's what I want dev_dbg() to output at KERN_DEBUG level
> > always and the hexdump only in the dynamic case.
> 
> Joe, I'm trying to understand your objection. What you are proposing
> is that the debug output is present at the KERN_DEBUG level in the
> CONFIG_DYNAMIC_DEBUG=n case and that's not what either use case wants.
> What breaks by letting users call dynamic_hex_dump() directly?

Call it hex_dump_dbg and I have no objections.

The "dynamicism" is a side effect of not having DEBUG
defined.  dev_dbg will emit if DEBUG is declared regardless
of dynamic_debug.

This new function should have the same behavior.