On 01/19/2015 08:05 PM, Rusty Russell wrote: > Oleg Nesterov <[email protected]> writes: >> On 01/17, Rasmus Villemoes wrote: >>> >>> Using kasprintf to get the function name makes us look up the name >>> twice, along with all the vsnprintf overhead of parsing the format >>> string etc. It also means there is an allocation failure case to deal >>> with. Since symbol_string in vsprintf.c would anyway allocate an array >>> of size KSYM_SYMBOL_LEN on the stack, that might as well be done up >>> here. >>> >>> Signed-off-by: Rasmus Villemoes <[email protected]> >>> --- >>> >>> Notes: >>> I don't know how expensive it is to do the symbol lookup for each >>> initcall. It might be worthwhile adding an >>> >>> if (list_empty(&blacklisted_initcalls)) >>> return false; >>> >>> at the very beginning of initcall_blacklisted(), since this is a debug >>> feature and the blacklist is indeed usually empty. >> >> If we want to optimize this... I am wondering if we can change >> initcall_blacklist() >> >> - entry->buf = alloc_bootmem(strlen(str_entry) + 1); >> + ebtry->fn = kallsyms_lookup_name(str_entry); >> >> and then change initcall_blacklisted() to just compare the pointers. > > That would make far, far more sense. It would fail for modules of > course, but that might be OK. Prarit, this was your code; does it > matter?
It does actually matter to me. I've been using it to blacklist modules at boot as well ... and it works really well :) So I'm okay with the original patch but not the second suggested change. P. > > Cheers, > Rusty. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
