From 2f51f9884f6a36b0fe9636d5a1937e5cbd25723b Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 13 Nov 2009 19:51:39 -0800 Subject: [PATCH] rcu: Eliminate __rcu_pending() false positives Now that there are both ->gpnum and ->completed fields in the rcu_node structure, __rcu_pending() should check rdp->gpnum and rdp->completed against rnp->gpnum and rdp->completed, respectively, instead of the prior comparison against the rcu_state fields rsp->gpnum and rsp->completed. Given the old comparison, __rcu_pending() could return 1, resulting in a needless raise_softirq(RCU_SOFTIRQ). This useless work would happen if RCU responded to a scheduling-clock interrupt after the rcu_state fields had been updated, but before the rcu_node fields had been updated. Changing the comparison from the rcu_state fields to the rcu_node fields prevents this useless work from happening. Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <12581706991966-git-send-email-> Signed-off-by: Ingo Molnar --- Reading git-format-patch failed