Re: [PATCH][SMACK] convert smack rule list to linux list

etienne
2009-02-22T13:14:52Z

Tetsuo Handa wrote:
> etienne wrote:
>> diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
>> index 2e0b83e..3dc312d 100644
>> --- a/security/smack/smack_access.c
>> +++ b/security/smack/smack_access.c
>> @@ -87,7 +87,6 @@ static u32 smack_next_secid = 10;
>> int smk_access(char *subject_label, char *object_label, int request)
>> {
>> u32 may = MAY_NOT;
>> - struct smk_list_entry *sp;
>> struct smack_rule *srp;
>>
>> /*
>> @@ -139,8 +138,8 @@ int smk_access(char *subject_label, char *object_label, int request)
>> * access (e.g. read is included in readwrite) it's
>> * good.
>> */
>> - for (sp = smack_list; sp != NULL; sp = sp->smk_next) {
>> - srp = &sp->smk_rule;
>> +
>> + list_for_each_entry(srp, &smack_rule_list, list) {
>>
>> if (srp->smk_subject == subject_label ||
>> strcmp(srp->smk_subject, subject_label) == 0) {
>
> Use of standard doubly linked list requires a lock, doesn't it?
> What lock protects smack_rule_list?
>
you're right;

what's the best way, using a rcu variant for "list_for_each, container_of ...etc" ?
(concurrent list insertion are already protected with a mutex, so rcu must the good idea for the read side)

thanks,
Etienne