Messages in this thread | | | From | "Luck, Tony" <> | Subject | RE: [regression] Re: [PATCH 2/3] futex: Sanitize cmpxchg_futex_value_locked API | Date | Mon, 5 Mar 2012 23:21:53 +0000 |
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> It doesn't look like the return value (r8) is actually being set beyond > initialized to 0. If there is some ia64 instruction that modifies it, GCC > doesn't know about it from the inline assembly (r8 doesn't appear in the > inputs/outputs list). From looking at the x86 version (agh, inline asm is > hard to parse), it does modify the return value based on whether the > comparison was a success or not, and the return value is certainly used by > the callers.
The commit comment for the change makes it sound like the return value is an error code (-ENOSYS if the function isn't implemented/configured; -EFAULT if the user address is bogus) - or zero if nothing bad happened.
Not "the comparison was a success or not".
What's the real answer? The ia64 code is returning 0 regardless of whether the compare/exchange found the old value or not. Is this a bad assumption?
-Tony
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