Section mismatch warnings for early memory allocations

Section mismatch warnings for early memory allocations

[Luck, Tony]

Checking for section mismatches across all of vmlinux is kicking
out a bunch of new warnings.  Many of them real, but I have a
few from routines like this:

foo(...)
{
	static int first_time = 1;

	if (first_time) {
		all_i_need = alloc_bootmem(NR_CPUS * xxx);
		first_time = 0;
	}
	... use smp_processor_id() to use pre-allocated memory ...
}


Now this is safe, since the first call to foo is made when alloc_bootmem
is still available.  But it kicks out a "Section mismatch" warning since
a non __init routine (foo) is calling an __init one.

Any suggestions on how to tell modpost that this is safe?

-Tony

Re: Section mismatch warnings for early memory allocations

[Sam Ravnborg]

On Mon, Jul 23, 2007 at 09:22:14AM -0700, Luck, Tony wrote:
> Checking for section mismatches across all of vmlinux is kicking
> out a bunch of new warnings.  Many of them real, but I have a
> few from routines like this:
> 
> foo(...)
> {
> 	static int first_time = 1;
> 
> 	if (first_time) {
> 		all_i_need = alloc_bootmem(NR_CPUS * xxx);
> 		first_time = 0;
> 	}
> 	... use smp_processor_id() to use pre-allocated memory ...
> }
> 
> 
> Now this is safe, since the first call to foo is made when alloc_bootmem
> is still available.  But it kicks out a "Section mismatch" warning since
> a non __init routine (foo) is calling an __init one.
> 
> Any suggestions on how to tell modpost that this is safe?
Best way is to use __init_refok like this:

/*
 * Call an __init function only first time as guarded by first_time.
 * Teach modpost that this is OK.
 */
void __init_refok foo()
{
	if (first_time) {
		all_i_need = alloc_bootmem(NR_CPUS * xxx);
		first_time = 0;
	}
}

	Sam