Messages in this thread | | | Date | Thu, 16 Oct 2008 15:08:55 +0900 | From | Tejun Heo <> | Subject | Re: [PATCH] stop gcc warning about uninitialized 'dev' in ata_scsi_scan_host |
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Elias Oltmanns wrote: >> I think the current policy is blaming gcc but I also added quite a few >> bogus NULL initializations here and there and caught several bugs thanks >> to those warnings. We can think about adding an additional annotation >> with leading double underbars which indicate that certain pointer >> arguments to functions expect (or are okay with) pointers to >> uninitialized variables which should be able to remove many of those >> spurious warnings (on the caller side, the compiler can ignore the >> warning and on the callee side the compiler can check whether it's being >> dereferenced without being written to). Does anyone know whether gcc >> already has that type of annotation? > > Well, I don't know of this particular kind of annotation. However, I > don't quite see how that would solve the reported issue.
I was thinking about the warning in sata_via.c and for such cases the compiler doesn't have any other way of figuring out whether it's okay or not (the sata_via case, the compiler can actually do as the callee is in the same file but you know what I mean).
> Here, dev is a local variable and the warning is generated due to > the line > > if (dev != last_failed_dev) { > > For this sort of thing we have: > > struct ata_device *uninitialized_var(dev);
Ah.. thanks.
> Or is that precisely the thing you did *not* want?
I don't know. Later versions of gcc doesn't issue warning because it knows "if (!link)" always triggers if dev is not initialized. I don't think we should be adding those annotations if the current gen compiler can already figure that out as it only decreases debuggability when something actually gets broken there.
Thanks.
-- tejun
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