On 05/06/2016 04:37 AM, Kevin Wolf wrote: > Am 05.05.2016 um 01:55 hat Eric Blake geschrieben: >> I was thrown by the fact that the public type BlockRequest had >> an anonymous union, but no obvious discriminator. Turns out >> that the only client of the second branch of the union was code >> internal to io.c, and that with a slight abuse of QEMUIOVector* >> to pass a void* pointer, we can make the public interface less >> confusing. >> >> (Yes, I know that strict C doesn't guarantee that you can cast >> void* to the wrong type and then back to void* - it only >> guarantees the reverse direction of the original pointer to >> void* and back to the original type - but we already have other >> assumptions throughout the qemu code base that assume that all >> pointers are interchangeable in representation). >> >> Signed-off-by: Eric Blake <[email protected]> > > Do you really think abusing fields makes things clearer than using a > union? We could just add comments instead that tell which branch is used > for what. And after my patch "block: Remove bdrv_aio_multiwrite()", I > think the struct isn't part of a public interface any more anyway.
Oh, you're right! Consider this patch severed from the series (I may still send a documentation patch, and/or move the struct out of the public header into block_int.h, but it is sufficiently unrelated to the rest of the series). -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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