On Friday 18 February 2011 13:58:52 Greg KH wrote:
> On Fri, Feb 18, 2011 at 01:55:04PM +1300, Ryan Mallon wrote:
> > On 02/18/2011 01:43 PM, Mark Brown wrote:
> > > On Thu, Feb 17, 2011 at 04:33:53PM -0800, Greg KH wrote:
> > >> On Fri, Feb 18, 2011 at 12:01:50AM +0000, Mark Brown wrote:
> > >>> For the proc stuff - for tracing stuff then tracepoints are likely to
> > >>> be a good option if it's useful to people.
> > >>
> > >> Then use the in-kernel tracing functionality, don't roll your own.
> > >> And that is not in /proc, so it should be there for this filesystem
> > >> either.
> > >
> > > That'd be the tracepoints I was mentioning, then...
> >
> > Are you suggesting that the yaffs_trace function should be replaced with
> > tracepoints?
> >
> > yaffs_trace is basically just a wrapper around printk, which I suggested
> > should be replaced with pr_debug so that it can be compiled out
> > completely. Other drivers and filesystems have similar custom debugging
> > functions.
> >
> > I haven't used tracepoints, but it seems like they are better suited to
> > tracing specific events than as a general printk style debugging
> > replacement?
The procfs is not used for tracing as , it is just one of the two ways
ofsetting a trace mask to select what to trace (the other is to set a trace
mask).
eg. echo +gc > /proc/yaffs
turns on the garbage collector tracing.
I will remove the /proc interface and write a userspace script to do the
equivalent.
Realtime selection of tracing is valuable. It allows you to set up a test case
with tracing disabled then select what you want to trace to get detail as you
run the test case
I still intend to keep the tracing printk-based tracing:
#define yaffs_trace(msk, fmt, ...) do { \
if (yaffs_trace_mask & (msk)) \
printk(KERN_DEBUG "yaffs: " fmt "\n", ##__VA_ARGS__); \
} while (0)
> If you want printk(), then yes, use pr_debug() as it ties into the
> dynamic debug infrastructure, which is great.
>
> Then you can remove the proc files, as the kernel already controls the
> debug interface through the standard way, no need for a custom one.
Thanks.
I was not aware of pr_debug I shall investigate how it works.
-- CHarles
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