Messages in this thread | | | Date | Mon, 4 Jun 2007 09:26:41 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: SLUB: Return ZERO_SIZE_PTR for kmalloc(0) |
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On Mon, 4 Jun 2007, Pekka Enberg wrote: > > Ok, makes sense. I guess I might as well throw my suggestion in the > mix. Lets create a new kmalloc cache for zero-length objects where > object size is zero but there are regular red-zones on both sides.
Well, the red-zones won't catch readers, and more importantly, even for writers they are *really* inconvenient, because it will just tell you something bad happened, it won't tell you *where* it happened.
Since comparing the addresses of two zero-sized allocations is insane and not done _anyway_, it's just much better to return an invalid address.
The thing is, why *should* we care about comparing addresses? We'll give the right result (you got many perfectly separate allocations, they're just zero bytes apart, exactly like you asked for!). The fact that C++ has some semantics for it is not a good argument - C++ is a broken language, and it's not the language we use for the kernel anyway.
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