On Mon, 2012-08-13 at 13:18 -0700, Greg Kroah-Hartman wrote: > From: Greg KH <gre...@linuxfoundation.org> > > 3.5-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Will Deacon <will.dea...@arm.com> > > commit a76d7bd96d65fa5119adba97e1b58d95f2e78829 upstream. > > The open-coded mutex implementation for ARMv6+ cores suffers from a > severe lack of barriers, so in the uncontended case we don't actually > protect any accesses performed during the critical section. > > Furthermore, the code is largely a duplication of the ARMv6+ atomic_dec > code but optimised to remove a branch instruction, as the mutex fastpath > was previously inlined. Now that this is executed out-of-line, we can > reuse the atomic access code for the locking (in fact, we use the xchg > code as this produces shorter critical sections). > > This patch uses the generic xchg based implementation for mutexes on > ARMv6+, which introduces barriers to the lock/unlock operations and also > has the benefit of removing a fair amount of inline assembly code. [...]
Here also, I think this should be deferred. Ben. -- Ben Hutchings I say we take off; nuke the site from orbit. It's the only way to be sure.
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