Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH] Futexes IV (Fast Lightweight Userspace Semaphores) | Date | Wed, 06 Mar 2002 12:46:25 +1100 |
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In message <Pine.LNX.4.44.0203051433400.1475-100000@blue1.dev.mcafeelabs.com> y ou write: > On Tue, 5 Mar 2002, Rusty Russell wrote: > > > + pos_in_page = ((unsigned long)uaddr) % PAGE_SIZE; > > + > > + /* Must be "naturally" aligned, and not on page boundary. */ > > + if ((pos_in_page % __alignof__(atomic_t)) != 0 > > + || pos_in_page + sizeof(atomic_t) > PAGE_SIZE) > > + return -EINVAL; > > How can this : > > (pos_in_page % __alignof__(atomic_t)) != 0 > > to be false, and together this : > > pos_in_page + sizeof(atomic_t) > PAGE_SIZE > > to be true ?
You're assuming that __alignof__(atomic_t) = N * sizeof(atomic_t), where N is an integer.
If alignof == 1, and sizeof == 4, you lose. I prefer to be future-proof.
This means I should clarify the comment... Rusty. -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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