diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2016-11-02 14:12:05 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-01-16 15:47:53 -0800 |
| commit | 8b2f63ab05eb233b2b396e133889ce3d1d30d944 (patch) | |
| tree | 34158316a74053a5051a2277d65615dbb41d4e24 /kernel/rcu | |
| parent | 6563de9d6f1336157c9861bcd9864e0b47d65f9d (diff) | |
rcu: Abstract the dynticks snapshot operation
This commit is the second step towards full abstraction of all accesses to
the ->dynticks counter, implementing the previously open-coded atomic
add of zero in a new rcu_dynticks_snap() function. This abstraction will
ease changes o the ->dynticks counter operation.
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 | 19 | ||||
| -rw-r--r-- | kernel/rcu/tree_exp.h | 6 |
2 files changed, 18 insertions, 7 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 14e283c351f6..805d55ee0b2a 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -282,6 +282,17 @@ static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { }; /* + * Snapshot the ->dynticks counter with full ordering so as to allow + * stable comparison of this counter with past and future snapshots. + */ +static int rcu_dynticks_snap(struct rcu_dynticks *rdtp) +{ + int snap = atomic_add_return(0, &rdtp->dynticks); + + return snap; +} + +/* * Do a double-increment of the ->dynticks counter to emulate a * momentary idle-CPU quiescent state. */ @@ -1049,7 +1060,9 @@ void rcu_nmi_exit(void) */ bool notrace __rcu_is_watching(void) { - return atomic_read(this_cpu_ptr(&rcu_dynticks.dynticks)) & 0x1; + struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks); + + return atomic_read(&rdtp->dynticks) & 0x1; } /** @@ -1132,7 +1145,7 @@ static int rcu_is_cpu_rrupt_from_idle(void) static int dyntick_save_progress_counter(struct rcu_data *rdp, bool *isidle, unsigned long *maxj) { - rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks); + rdp->dynticks_snap = rcu_dynticks_snap(rdp->dynticks); rcu_sysidle_check_cpu(rdp, isidle, maxj); if ((rdp->dynticks_snap & 0x1) == 0) { trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti")); @@ -1157,7 +1170,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp, int *rcrmp; unsigned int snap; - curr = (unsigned int)atomic_add_return(0, &rdp->dynticks->dynticks); + curr = (unsigned int)rcu_dynticks_snap(rdp->dynticks); snap = (unsigned int)rdp->dynticks_snap; /* diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index e59e1849b89a..011f626b2fd8 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -356,10 +356,9 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp, mask_ofl_test = 0; for_each_leaf_node_possible_cpu(rnp, cpu) { struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); - struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); rdp->exp_dynticks_snap = - atomic_add_return(0, &rdtp->dynticks); + rcu_dynticks_snap(rdp->dynticks); if (raw_smp_processor_id() == cpu || !(rdp->exp_dynticks_snap & 0x1) || !(rnp->qsmaskinitnext & rdp->grpmask)) @@ -380,12 +379,11 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp, for_each_leaf_node_possible_cpu(rnp, cpu) { unsigned long mask = leaf_node_cpu_bit(rnp, cpu); struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); - struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); if (!(mask_ofl_ipi & mask)) continue; retry_ipi: - if (atomic_add_return(0, &rdtp->dynticks) != + if (rcu_dynticks_snap(rdp->dynticks) != rdp->exp_dynticks_snap) { mask_ofl_test |= mask; continue; |