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Date: Fri, 19 Sep 2014 13:57:54 -0700 From: Josh Triplett <josh@...htriplett.org> To: Pranith Kumar <bobby.prani@...il.com> Cc: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, Steven Rostedt <rostedt@...dmis.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Lai Jiangshan <laijs@...fujitsu.com>, "open list:READ-COPY UPDATE..." <linux-kernel@...r.kernel.org> Subject: Re: [RFC PATCH] rcu: Change use of __this_cpu ops on a bool type On Fri, Sep 19, 2014 at 01:26:03PM -0400, Pranith Kumar wrote: > __this_cpu_{read/write}() uses sizeof() to determine the size of the variable. > Using this operation on a bool type causes sparse to complain. > > I checked the generated code and there is only a slight difference in > instructions generated. > > I am not sure this warning by sparse is really valid, but let us silence it > anyways. > > Signed-off-by: Pranith Kumar <bobby.prani@...il.com> I believe this warning was actually fixed with current versions of Sparse; there was some discussion and a patch on the linux-sparse mailing list. Can you please recheck with the latest Sparse from git, and if it still breaks, please raise that on linux-sparse? > kernel/rcu/tree.c | 12 ++++++++---- > kernel/rcu/tree_plugin.h | 6 ++++-- > 2 files changed, 12 insertions(+), 6 deletions(-) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index bc085e5..85f228a 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -186,21 +186,25 @@ static int rcu_gp_in_progress(struct rcu_state *rsp) > */ > void rcu_sched_qs(void) > { > - if (!__this_cpu_read(rcu_sched_data.passed_quiesce)) { > + struct rcu_data *rdp = __this_cpu_ptr(&rcu_sched_data); > + > + if (!rdp->passed_quiesce) { > trace_rcu_grace_period(TPS("rcu_sched"), > __this_cpu_read(rcu_sched_data.gpnum), > TPS("cpuqs")); > - __this_cpu_write(rcu_sched_data.passed_quiesce, 1); > + rdp->passed_quiesce = true; > } > } > > void rcu_bh_qs(void) > { > - if (!__this_cpu_read(rcu_bh_data.passed_quiesce)) { > + struct rcu_data *rdp = __this_cpu_ptr(&rcu_bh_data); > + > + if (!rdp->passed_quiesce) { > trace_rcu_grace_period(TPS("rcu_bh"), > __this_cpu_read(rcu_bh_data.gpnum), > TPS("cpuqs")); > - __this_cpu_write(rcu_bh_data.passed_quiesce, 1); > + rdp->passed_quiesce = true; > } > } > > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index 77f9376..98de303 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -143,11 +143,13 @@ EXPORT_SYMBOL_GPL(rcu_batches_completed); > */ > static void rcu_preempt_qs(void) > { > - if (!__this_cpu_read(rcu_preempt_data.passed_quiesce)) { > + struct rcu_data *rdp = __this_cpu_ptr(&rcu_preempt_data); > + > + if (!rdp->passed_quiesce) { > trace_rcu_grace_period(TPS("rcu_preempt"), > __this_cpu_read(rcu_preempt_data.gpnum), > TPS("cpuqs")); > - __this_cpu_write(rcu_preempt_data.passed_quiesce, 1); > + rdp->passed_quiesce = true; > barrier(); /* Coordinate with rcu_preempt_check_callbacks(). */ > current->rcu_read_unlock_special.b.need_qs = false; > } > -- > 2.1.0 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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