[PATCH] kallsyms: optimize kallsyms_lookup_name() for a few cases

[Naveen N. Rao]

Excerpts from David Laight's message of April 25, 2017 22:06:
> From: Naveen N. Rao
>> Sent: 25 April 2017 17:18
>> 1. Fail early for invalid/zero length symbols.
>> 2. Detect names of the form <mod:name> and skip checking for kernel
>> symbols in that case.
>> 
>> Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
>> ---
>> Masami, Michael,
>> I have added two very simple checks here, which I felt is good to have,
>> rather than the elaborate checks in the previous version. Given the
>> change in module code to use strnchr(), the checks are now safe and
>> further tests are not probably not that useful.
> ...
>> +	if (strnchr(name, MODULE_NAME_LEN, ':'))
>> +		return module_kallsyms_lookup_name(name);
> 
> Should that be MODULE_NAME_LEN - 1 ?

The ':' character _follows_ the module name, which can itself be upto 
MODULE_NAME_LEN - 1 characters. So, we should look for it till 
MODULE_NAME_LEN.

Thanks for the review,
- Naveen