Messages in this thread | | | From | Elias Oltmanns <> | Subject | Re: [PATCH] stop gcc warning about uninitialized 'dev' in ata_scsi_scan_host | Date | Thu, 16 Oct 2008 08:02:08 +0200 |
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Tejun Heo <tj@kernel.org> wrote: > Alex Chiang wrote: >> * Tejun Heo <tj@kernel.org>: > >>> Alex Chiang wrote: >>>> Shuts up gcc-3.4.5-glibc-2.3.6 when it complains of: >>>> >>>> drivers/ata/libata-scsi.c: In function `ata_scsi_scan_host': >>>> drivers/ata/libata-scsi.c:3225: warning: 'dev' might be used >>>> uninitialized in this function >>>> >>>> Signed-off-by: Alex Chiang <achiang@hp.com> >>> Nacked-by: Tejun Heo <tj@kernel.org> >>> >>> Some gcc versions complain about sata_via, others complain >>> about something else. Some versions complain about some >>> iterator usages while not complaining about others, but none of >>> those complaints is actually wrong or dangerous. I don't think >>> adding = NULL whenever some version of gcc complains is the >>> right approach. >> >> Hm, ok. >> >> I guess we don't want to sprinkle these around all over the place >> just to solve cosmetic issues, which makes sense, but is there >> some other approach we could take instead? Any suggestions? Or >> just live with it? > > 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. 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);
Or is that precisely the thing you did *not* want?
Regards,
Elias
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