>>> On 28.01.15 at 15:29, <tip...@zytor.com> wrote: > Commit-ID: 81907478c4311a679849216abf723999184ab984 > Gitweb: > http://git.kernel.org/tip/81907478c4311a679849216abf723999184ab984 > Author: Jan Beulich <jbeul...@suse.com> > AuthorDate: Fri, 23 Jan 2015 08:25:38 +0000 > Committer: Ingo Molnar <mi...@kernel.org> > CommitDate: Wed, 28 Jan 2015 13:14:12 +0100 > > sched/fair: Avoid using uninitialized variable in preferred_group_nid() > > At least some gcc versions - validly afaict - warn about potentially > using max_group uninitialized: There's no way the compiler can prove > that the body of the conditional where it and max_faults get set/ > updated gets executed; in fact, without knowing all the details of > other scheduler code, I can't prove this either. > > Generally the necessary change would appear to be to clear max_group > prior to entering the inner loop, and break out of the outer loop when > it ends up being all clear after the inner one. This, however, seems > inefficient, and afaict the same effect can be achieved by exiting the > outer loop when max_faults is still zero after the inner loop. > > [ mingo: changed the solution to zero initialization: uninitialized_var() > needs to die, as it's an actively dangerous construct: if in the future > a known-proven-good piece of code is changed to have a true, buggy > uninitialized variable, the compiler warning is then supressed...
But you went farther than that: You also dropped the breaking out of the outer loop. Yet that has - beyond the fixing of the bug here - the desirable effect of not continuing for perhaps many iterations when nothing new can ever be found anymore. Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
