On 09/26/2013 01:58 PM, Chen Gang wrote: > On 09/25/2013 12:34 PM, Chen Gang wrote: >> On 09/25/2013 09:47 AM, Chen Gang wrote: >>> On 09/25/2013 09:14 AM, Tejun Heo wrote: >>>> On Wed, Sep 25, 2013 at 09:06:52AM +0800, Chen Gang wrote: >>>>> OK, I see, the 'root cause' is: "you are not the related maintainer >>>>> either", so it is really necessary for me to spend additional time >>>>> resource on it :-(. >>>> >>>> Yeah, at least partly. That and the fact that I'm not too willing to >>>> dig into the code without further evidence. It isn't anything strange >>>> to ask tho and I'm likely to do that even for subsystems that I know >>>> intimately if the subject code has been stable / stale for years and >>>> the analysis doesn't seem immediately convincing. And, if my >>>> experience is anything to go by, it's not too unlikely that you might >>>> hit something which doesn't agree with your current assumptions while >>>> trying to actually trigger the problem. >>>> >>>> Thanks. >>>> > > Oh, not cause issue, the reason is "'groups' exports extern variable > 'init_groups', when start process, default 'cred' will set it to be > sure of groups always be initialized". > > Hmm... but after all, I still think this file need be improved: "remove > the group_info checking in groups_search()", please help check, thanks. > > -------------------------------patch begin------------------------------ > > kernel/groups.c: remove useless "!group_info" checking in groups_search(). > > Since groups_free() need not check 'group_info', groups_search() need > not, either, and then in_group_p() and in_egroup_p(), either. > > > 'groups' assumes kernel mode callers are sure of 'group_info' valid. >
Oh, need use "callers" instead of "kernel mode callers". > When process starts, the related kernel mode caller need set default > 'group_info' firstly (extern variable 'init_group'). > And also need append one sentence: "and the callers also need be sure of "&init_group" is not passed to groups_free()." > If groups_alloc() fails, the caller must not call any related API again > with the related invalid 'group_info'. > > > Signed-off-by: Chen Gang <[email protected]> > --- > kernel/groups.c | 3 --- > 1 files changed, 0 insertions(+), 3 deletions(-) > > diff --git a/kernel/groups.c b/kernel/groups.c > index 90cf1c3..0a7f81d 100644 > --- a/kernel/groups.c > +++ b/kernel/groups.c > @@ -136,9 +136,6 @@ int groups_search(const struct group_info *group_info, > kgid_t grp) > { > unsigned int left, right; > > - if (!group_info) > - return 0; > - > left = 0; > right = group_info->ngroups; > while (left < right) { > -- Chen Gang -- Chen Gang -- 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/
