Messages in this thread | | | Date | Fri, 22 Oct 2010 16:04:05 +0200 | From | Jens Axboe <> | Subject | Re: [PATCH] cfq-iosched: Fix a gcc 4.5 warning and put some comments |
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On 2010-10-22 15:31, Vivek Goyal wrote: > On Fri, Oct 22, 2010 at 09:46:19AM +0200, Jens Axboe wrote: >> On 2010-10-21 20:24, Vivek Goyal wrote: >>> - Andi encountedred following warning with gcc 4.5 >>> >>> linux/block/cfq-iosched.c: In function ‘cfq_dispatch_requests’: >>> linux/block/cfq-iosched.c:2156:3: warning: array subscript is above array >>> bounds >>> >>> - Warning happens due to following code. >>> >>> slice = group_slice * count / >>> max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], >>> cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); >>> >>> gcc is complaining about cfqg->busy_queues_avg[] being indexed by CFQ >>> prio classes (RT, BE and IDLE) while the array size is only 2. >>> >>> - At run time, we never access cfqg->busy_queues_avg[IDLE] and return from >>> function before this code hits. >>> >>> - To fix warning increase the array size though it will remain unused. This >>> patch also puts some comments to clarify some of the confusions. >>> >>> - I have taken Jens's patch and modified it a bit. >>> >>> - Compile tested with gcc 4.4 and boot tested. I don't have gcc 4.5 >>> running, Andi can you please test it with gcc 4.5 to make sure it >>> worked. >>> >>> Reported-by: Andi Kleen <ak@linux.intel.com> >>> Signed-off-by: Vivek Goyal <vgoyal@redhat.com> >>> Signed-off-by: Jens Axboe <axboe@kernel.dk> >> >> Thanks, I'll put this one in. BTW, you can't just add a signed-off-by >> from me (or anyone else, for that matter), they have to be provided >> explicitly by each individual. > > Ok, sorry about that. > > So in general, if I happen to pick somebody's patch, modify it and repost > it, how do I reflect the Signed-off-by of original author.
What I usually do is leave the original signed-off-by, then describe my changes, then add my signed-off-by. I think that is acceptable behaviour. It's very different from adding a signed-off-by to something that hasn't been signed-off by the original author yet that's legally an issue. But hey, IANAL :-)
-- Jens Axboe
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