Messages in this thread | | | Date | Wed, 24 Oct 2012 09:31:25 +0800 | From | Tang Chen <> | Subject | Re: [PATCH v2 1/2] Replace if statement with WARN_ON_ONCE() in cmci_rediscover(). |
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Hi Luck, Borislav,
OK, since you all think it is not necessary, I think I will drop patch1. And thanks for your comments. :)
So, how about patch2 ? If you need more detail, please tell me. Thanks. :)
On 10/24/2012 12:16 AM, Luck, Tony wrote: >> First of all, I do think I was answering your question. As I said >> before, if an online cpu == dying here, there must be something wrong. >> Am I right here ? > > Yes - but there is a fuzzy line over where it is good to check for "something wrong" > or whether to trust that the caller of the function knew what they were doing. > > For example we trust that "dying" is a valid cpu number. If we were > super-paranoid that someone might change the code and call us with a > bad argument, we might add: > > BUG_ON(dying< 0 || dying>= MAX_NR_CPUS); > > This would certainly help debug the case if someone did make a bogus > change ... but I think it is clear that this test is way past the fuzzy line and > into pointless. > > Back to the case in question: do we think there is a credible case where > the "dying" cpu can show up in our "for_each_cpu_online()" loop? The > original author of the code was worried enough to make a test, but thought > that the appropriate action was to silently skip it. You want to add a WARN_ON, > which will cause users who read the console logs to worry, but that most users > will never see. > > -Tony
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