diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2016-12-01 09:55:27 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-01-23 11:44:18 -0800 |
| commit | 38d30b336ccf8ee98e0e494a13738a0fade5a5e6 (patch) | |
| tree | f3d753934aa5014c7ef5837130d4c1229b42b6e6 /kernel/rcu | |
| parent | 3a19b46a5c17b12ef0691df19c676ba3da330a57 (diff) | |
rcu: Adjust FQS offline checks for exact online-CPU detection
Commit 7ec99de36f40 ("rcu: Provide exact CPU-online tracking for RCU"),
as its title suggests, got rid of RCU's remaining CPU-hotplug timing
guesswork. This commit therefore removes the one-jiffy kludge that was
used to paper over this guesswork.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 17 |
1 files changed, 2 insertions, 15 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index d8245cbd08f9..6e4b1dcebeb2 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1276,21 +1276,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp, return 1; } - /* - * Check for the CPU being offline, but only if the grace period - * is old enough. We don't need to worry about the CPU changing - * state: If we see it offline even once, it has been through a - * quiescent state. - * - * The reason for insisting that the grace period be at least - * one jiffy old is that CPUs that are not quite online and that - * have just gone offline can still execute RCU read-side critical - * sections. - */ - if (ULONG_CMP_GE(rdp->rsp->gp_start + 2, jiffies)) - return 0; /* Grace period is not old enough. */ - barrier(); - if (cpu_is_offline(rdp->cpu)) { + /* Check for the CPU being offline. */ + if (!(rdp->grpmask & rcu_rnp_online_cpus(rnp))) { trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("ofl")); rdp->offline_fqs++; return 1; |