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.
Oleg.
> init/main.c | 8 ++------
> 1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/init/main.c b/init/main.c
> index 61b993767db5..286602b677de 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -733,22 +733,18 @@ static bool __init_or_module
> initcall_blacklisted(initcall_t fn)
> {
> struct list_head *tmp;
> struct blacklist_entry *entry;
> - char *fn_name;
> + char fn_name[KSYM_SYMBOL_LEN];
>
> - fn_name = kasprintf(GFP_KERNEL, "%pf", fn);
> - if (!fn_name)
> - return false;
> + sprint_symbol_no_offset(fn_name, (unsigned long)fn);
>
> list_for_each(tmp, &blacklisted_initcalls) {
> entry = list_entry(tmp, struct blacklist_entry, next);
> if (!strcmp(fn_name, entry->buf)) {
> pr_debug("initcall %s blacklisted\n", fn_name);
> - kfree(fn_name);
> return true;
> }
> }
>
> - kfree(fn_name);
> return false;
> }
> #else
> --
> 2.1.3
>
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