On Wed 31-10-12 12:44:03, Tejun Heo wrote: [...] > local_irq_save/restore() from cgroup_clear_css_refs() are replaced > with local_irq_disable/enable() for simplicity. This is safe as > cgroup_rmdir() is always called with IRQ enabled. Note that this IRQ > switching is necessary to make CSS deactivation and CSS_REMOVED > assertion atomic against css_tryget() and will be removed by future > changes.
local_irq_disable doesn't guarantee atomicity, because other CPUs will see the change in steps so this is a bit misleading. The real reason AFAICS is that we do not want to hang in css_tryget from IRQ context (does this really happen btw.?) which would interrupt cgroup_rmdir between we add CSS_DEACT_BIAS and the group is marked CGRP_REMOVED. Or am I still missing the point? [...] -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
