Re: [RFC][PATCH v2 4/5] mutex: Disable preemtion between modifyinglock->owner and locking/unlocking mutex

[Peter Zijlstra]

On Tue, Jan 28, 2014 at 11:13:15AM -0800, Jason Low wrote:
> This RFC patch disables preemption between modifying lock->owner and
> locking/unlocking the mutex lock. This prevents situations where the owner
> can preempt between those 2 operations, which causes optimistic spinners to
> be unable to check if lock->owner is not on CPU. As mentioned in the
> thread for this v1 patchset, disabling preemption is a cheap operation.

In that same thread it was also said that this wasn't really an issue at
all. So what is the justification?

The patch is rather hideous.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/