On Tue, 2015-10-27 at 20:25 +0100, Stephane Eranian wrote: > This patch eliminates all known RCU violations detected > by the RCU checker (PROVE_RCU). The impact code paths > were all related to cgroup mode monitoring and involved > access a task's cgrp. > > V2 is updated to include suggestions from PeterZ to eliminate > some of the warnings without grabbing the rcu_read lock because > we know we are already holding the ctx->lock which prevents > the cgroup from disappearing while we are accessing it. > The trick, as suggested by Peter, is to modify the > perf_cgroup_from_task() to take an extra boolean parameter > to allow bypassing the lockdep test in the task_subsys_cstate() > macros. This patch uses this approach to update all calls the > perf_cgroup_from_task(). > V2 Patch relative to: > 8b3c8e6 Revert "rculist: Make list_entry_rcu() use lockless_dereference()" > > Signed-off-by: Stephane Eranian <eran...@google.com> > ---
Instead trusting caller to provide correct 'safe' boolean, what about using lockdep_is_held() ? This way, you keep full lockep support. A random example is #define rcu_dereference_rtnl(p) rcu_dereference_check(p, lockdep_rtnl_is_held()) -- 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/
