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SubjectRe: [PATCH] kernel: power: swap: mark a function as __init to save some memory
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Le 01/06/2020 à 00:11, Joe Perches a écrit :
> (adding Dan Carpenter)
>
> On Sun, 2020-05-31 at 23:00 +0200, Christophe JAILLET wrote:
>> 'swsusp_header_init()' is only called via 'core_initcall'.
>> It can be marked as __init to save a few bytes of memory.
>
> Hey Dan
>
> smatch has a full function calling tree right?
>
> Can smatch find unmarked functions called only by __init
> functions so those unmarked functions can be appropriately
> marked with __init like the below?
>

Hi, in case of interest for anyone, I actually find such things as follow:
- grep to spot xxx_initcall macro (see comments in the perl script
below)
- a perl script which tries to spot missing __init

The false positive rate is low.
Feel free to use and propose patches based on it.

CJ

________________________________________________
#!/usr/bin/perl

use warnings;
use strict;

# grep -r --include=*.c -E
'^[[:space:]]*(early|core|postcore|arch|subsys|fs|device|late)_initcall\(.*\)'
* > tmp.txt
my $tmp="tmp.txt";

open(my $fh, "<", $tmp);
while (my $line = <$fh>) {
# Each line looks like:
# net/mac80211/main.c:subsys_initcall(ieee80211_init);
if ($line =~ /^(.*):.*\((.*)\)/) {
system("grep -E '$2\\(void' $1 | grep -v -E '__.*init'");
}
}
close($fh)


>> ---
>> kernel/power/swap.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
>> index ca0fcb5ced71..01e2858b5fe3 100644
>> --- a/kernel/power/swap.c
>> +++ b/kernel/power/swap.c
>> @@ -1590,7 +1590,7 @@ int swsusp_unmark(void)
>> }
>> #endif
>>
>> -static int swsusp_header_init(void)
>> +static int __init swsusp_header_init(void)
>> {
>> swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
>> if (!swsusp_header)
>
>

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