On Tue, 24 Sep 2002 alfred@leakybucket.org wrote:
> 1) There's a comment in sys_futex(...) that says pos_in_page must not be
> on a page boundary. Could someone explain why?
what it wants to say: 'the futex word must not overflow into the next
page', ie. the futex word needs to be on a single page.
> 2) How is this ever true:
> pos_in_page + sizeof(int) > PAGE_SIZE
> when checking if pos_in_page is valid?
the full test is this:
pos_in_page = ((unsigned long)uaddr) % PAGE_SIZE;
if ((pos_in_page % __alignof__(int)) != 0
|| pos_in_page + sizeof(int) > PAGE_SIZE)
return -EINVAL;
what it says: 'uaddr must be naturally aligned, and the word must be on a
single page'. In theory it's possible that __alignof__(int) !=
sizeof(int).
Ingo
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This archive was generated by hypermail 2b29 : Mon Sep 30 2002 - 22:00:22 EST