From: "Paul E. McKenney" paulmck@kernel.org
[ Upstream commit ed4ae5eff4b38797607cbdd80da394149110fb37 ]
This commit applies the "noinstr" tag to the rcu_idle_enter() and rcu_idle_exit() functions, which are invoked from portions of the idle loop that cannot be instrumented. These tags require reworking the rcu_eqs_enter() and rcu_eqs_exit() functions that these two functions invoke in order to cause them to use normal assertions rather than lockdep. In addition, within rcu_idle_exit(), the raw versions of local_irq_save() and local_irq_restore() are used, again to avoid issues with lockdep in uninstrumented code.
This patch is based in part on an earlier patch by Jiri Olsa, discussions with Peter Zijlstra and Frederic Weisbecker, earlier changes by Thomas Gleixner, and off-list discussions with Yonghong Song.
Link: https://lore.kernel.org/lkml/20220515203653.4039075-1-jolsa@kernel.org/ Reported-by: Jiri Olsa jolsa@kernel.org Reported-by: Alexei Starovoitov ast@kernel.org Reported-by: Andrii Nakryiko andrii@kernel.org Signed-off-by: Paul E. McKenney paulmck@kernel.org Reviewed-by: Yonghong Song yhs@fb.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/rcu/tree.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index a4a9d68b1fdc..ef959bc207bc 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -620,8 +620,8 @@ static noinstr void rcu_eqs_enter(bool user) return; }
- lockdep_assert_irqs_disabled(); instrumentation_begin(); + lockdep_assert_irqs_disabled(); trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, atomic_read(&rdp->dynticks)); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current)); rcu_prepare_for_idle(); @@ -649,9 +649,9 @@ static noinstr void rcu_eqs_enter(bool user) * If you add or remove a call to rcu_idle_enter(), be sure to test with * CONFIG_RCU_EQS_DEBUG=y. */ -void rcu_idle_enter(void) +void noinstr rcu_idle_enter(void) { - lockdep_assert_irqs_disabled(); + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled()); rcu_eqs_enter(false); } EXPORT_SYMBOL_GPL(rcu_idle_enter); @@ -854,7 +854,7 @@ static void noinstr rcu_eqs_exit(bool user) struct rcu_data *rdp; long oldval;
- lockdep_assert_irqs_disabled(); + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled()); rdp = this_cpu_ptr(&rcu_data); oldval = rdp->dynticks_nesting; WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0); @@ -890,13 +890,13 @@ static void noinstr rcu_eqs_exit(bool user) * If you add or remove a call to rcu_idle_exit(), be sure to test with * CONFIG_RCU_EQS_DEBUG=y. */ -void rcu_idle_exit(void) +void noinstr rcu_idle_exit(void) { unsigned long flags;
- local_irq_save(flags); + raw_local_irq_save(flags); rcu_eqs_exit(false); - local_irq_restore(flags); + raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(rcu_idle_exit);