Messages in this thread | | | Subject | Re: [PATCH] sched: rt_rq runtime leakage bug fix | From | Peter Zijlstra <> | Date | Thu, 12 May 2011 12:12:30 +0200 |
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On Thu, 2011-05-12 at 01:30 +0800, Cheng Xu wrote: > > I tried but hit a boot-time error "Unable to handle kernel paging > request for data at address 0x100000008", and therefore would like to > propose an alternative patch like, > I probably made a silly mistake somehwere, it was after all something quickly typed in an email :-)
> #define for_each_rt_rq(rt_rq, iter, rq) \ > for (iter = list_entry_rcu(task_groups.next, typeof(*iter), list); \ > (&iter->list != &task_groups) && (rt_rq = iter->rt_rq[cpu_of(rq)]); \ > iter = list_entry_rcu(iter->list.next, typeof(*iter), list)) > > This worked, it seems to pass the tests. Is this correct from a scheduler perspective?
Creative ;-), it would be nice to know why the , operator version doesn't work though, since that looks to be the more conventional way to write it.
That said, I don't see a problem with using your existing on.
> For the not CONFIG_RT_GROUP_SCHED part, I used > > typedef struct rt_rq *rt_rq_iter_t; > > #define for_each_rt_rq(rt_rq, iter, rq) \ > (void) iter; \ > for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL) > > An alternative is > #define for_each_rt_rq(rt_rq, iter, rq) \ > for (rt_rq = iter = &rq->rt; iter; rt_rq = iter = NULL)
Tough call that, the first has a multi-statement macro, which is generally discouraged because then:
for() for_each_rt_rq() { }
will not work as expected, so I think we want the second version.
> The patch is attached below. Could you check whether it is workable? Thank you.
Yes, given how things are I can't really see it getting any better, thanks!
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