Mark Brown had written, on 08/06/2010 07:18 AM, the following:
On Fri, Aug 06, 2010 at 06:08:03AM -0500, Nishanth Menon wrote:
Well that is my motivation here. if driver reports a warning to kernel
syslog, well, I expect the log to contain the function name for me to
maintain faster.
That's really not the expectation for Linux log messages - the general
approach to find the source of a message is generally to just grep for
the message text which is usually very effective.
taking a small sample set of pr_xyz(); (pr which spans a single line):
$ git grep pr_ drivers/|grep ")"|grep __func__|wc -l
589
$ git grep pr_ drivers/|grep ")"|grep -v __func__|wc -l
5373
$ git grep pr_fmt drivers/|wc -l
138
Reading Documentation/dynamic-debug-howto.txt, I see that you are in a
one way right. I can get fine grained control over the log by enabling
CONFIG_DYNAMIC_DEBUG.
At the same time, I have wondered on the usage of pr_fmt() in many of
the drivers. in a way, if i wanted to be that verbose in a driver, I
could in theory do:
#define pr_fmt(fmt) "%s:" fmt, __func__ and get the benefit throughout
the file..
but overall, I still disagree that we dont need to have the function
name in log is a speed booster for maintenance folks.
a) when the strings are split up when they go multiple lines:
E.g.:
"abcd "
"efg"
print comes out abcd efg
i) you do a git grep "abcd efg" will return nada
ii) if you do a git grep of "abcd", you will probably see half a dozen
prints there, then open each file to see where the "real" message is,
and you find the file searching a bit
b) when there are couple more usage in cases of commonly used error
message- (e.g. invalid parameters), you end up getting multiple hits,
and you are left guessing where it came from
in this example: lets see: (on l-o pm branch):
git grep "DEBUG option not enabled" .
arch/arm/mach-omap2/smartreflex.c: pr_notice("DEBUG option
not enabled!\n \
arch/arm/mach-omap2/voltage.c: pr_notice("DEBUG option not
enabled!\n \
now open up both the files to find exactly what you are looking for.
c) time required:
$ time git grep "DEBUG option not enabled" .
arch/arm/mach-omap2/smartreflex.c: pr_notice("DEBUG option
not enabled!\n \
arch/arm/mach-omap2/voltage.c: pr_notice("DEBUG option not
enabled!\n \
real 1m34.722s
user 0m0.440s
sys 0m1.820s
Vs cscope or ctags where it is rather instantaneous if you know the
function name..
--
Regards,
Nishanth Menon
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