The following commit has been merged into the core/rcu branch of tip: Commit-ID: 9ea366f669ded353ae49754216c042e7d2f72ba6 Gitweb: https://git.kernel.org/tip/9ea366f669ded353ae49754216c042e7d2f72ba6 Author: Paul E. McKenney <paul...@kernel.org> AuthorDate: Thu, 13 Feb 2020 12:31:16 -08:00 Committer: Thomas Gleixner <t...@linutronix.de> CommitterDate: Tue, 19 May 2020 15:51:21 +02:00
rcu: Make RCU IRQ enter/exit functions rely on in_nmi() The rcu_nmi_enter_common() and rcu_nmi_exit_common() functions take an "irq" parameter that indicates whether these functions have been invoked from an irq handler (irq==true) or an NMI handler (irq==false). However, recent changes have applied notrace to a few critical functions such that rcu_nmi_enter_common() and rcu_nmi_exit_common() many now rely on in_nmi(). Note that in_nmi() works no differently than before, but rather that tracing is now prohibited in code regions where in_nmi() would incorrectly report NMI state. Therefore remove the "irq" parameter and inline rcu_nmi_enter_common() and rcu_nmi_exit_common() into rcu_nmi_enter() and rcu_nmi_exit(), respectively. Signed-off-by: Paul E. McKenney <paul...@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.char...@oracle.com> Link: https://lkml.kernel.org/r/20200505134101.617130...@linutronix.de --- kernel/rcu/tree.c | 47 ++++++++++++++-------------------------------- 1 file changed, 15 insertions(+), 32 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 0713ef3..9454016 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -664,16 +664,18 @@ noinstr void rcu_user_enter(void) } #endif /* CONFIG_NO_HZ_FULL */ -/* +/** + * rcu_nmi_exit - inform RCU of exit from NMI context + * * If we are returning from the outermost NMI handler that interrupted an * RCU-idle period, update rdp->dynticks and rdp->dynticks_nmi_nesting * to let the RCU grace-period handling know that the CPU is back to * being RCU-idle. * - * If you add or remove a call to rcu_nmi_exit_common(), be sure to test + * If you add or remove a call to rcu_nmi_exit(), be sure to test * with CONFIG_RCU_EQS_DEBUG=y. */ -static __always_inline void rcu_nmi_exit_common(bool irq) +noinstr void rcu_nmi_exit(void) { struct rcu_data *rdp = this_cpu_ptr(&rcu_data); @@ -704,7 +706,7 @@ static __always_inline void rcu_nmi_exit_common(bool irq) trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, atomic_read(&rdp->dynticks)); WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */ - if (irq) + if (!in_nmi()) rcu_prepare_for_idle(); instrumentation_end(); @@ -712,22 +714,11 @@ static __always_inline void rcu_nmi_exit_common(bool irq) rcu_dynticks_eqs_enter(); // ... but is no longer watching here. - if (irq) + if (!in_nmi()) rcu_dynticks_task_enter(); } /** - * rcu_nmi_exit - inform RCU of exit from NMI context - * - * If you add or remove a call to rcu_nmi_exit(), be sure to test - * with CONFIG_RCU_EQS_DEBUG=y. - */ -void noinstr rcu_nmi_exit(void) -{ - rcu_nmi_exit_common(false); -} - -/** * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle * * Exit from an interrupt handler, which might possibly result in entering @@ -749,7 +740,7 @@ void noinstr rcu_nmi_exit(void) void noinstr rcu_irq_exit(void) { lockdep_assert_irqs_disabled(); - rcu_nmi_exit_common(true); + rcu_nmi_exit(); } /* @@ -838,7 +829,7 @@ void noinstr rcu_user_exit(void) #endif /* CONFIG_NO_HZ_FULL */ /** - * rcu_nmi_enter_common - inform RCU of entry to NMI context + * rcu_nmi_enter - inform RCU of entry to NMI context * @irq: Is this call from rcu_irq_enter? * * If the CPU was idle from RCU's viewpoint, update rdp->dynticks and @@ -847,10 +838,10 @@ void noinstr rcu_user_exit(void) * long as the nesting level does not overflow an int. (You will probably * run out of stack space first.) * - * If you add or remove a call to rcu_nmi_enter_common(), be sure to test + * If you add or remove a call to rcu_nmi_enter(), be sure to test * with CONFIG_RCU_EQS_DEBUG=y. */ -static __always_inline void rcu_nmi_enter_common(bool irq) +noinstr void rcu_nmi_enter(void) { long incby = 2; struct rcu_data *rdp = this_cpu_ptr(&rcu_data); @@ -868,18 +859,18 @@ static __always_inline void rcu_nmi_enter_common(bool irq) */ if (rcu_dynticks_curr_cpu_in_eqs()) { - if (irq) + if (!in_nmi()) rcu_dynticks_task_exit(); // RCU is not watching here ... rcu_dynticks_eqs_exit(); // ... but is watching here. - if (irq) + if (!in_nmi()) rcu_cleanup_after_idle(); incby = 1; - } else if (irq) { + } else if (!in_nmi()) { instrumentation_begin(); if (tick_nohz_full_cpu(rdp->cpu) && rdp->dynticks_nmi_nesting == DYNTICK_IRQ_NONIDLE && @@ -914,14 +905,6 @@ static __always_inline void rcu_nmi_enter_common(bool irq) } /** - * rcu_nmi_enter - inform RCU of entry to NMI context - */ -noinstr void rcu_nmi_enter(void) -{ - rcu_nmi_enter_common(false); -} - -/** * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle * * Enter an interrupt handler, which might possibly result in exiting @@ -946,7 +929,7 @@ noinstr void rcu_nmi_enter(void) noinstr void rcu_irq_enter(void) { lockdep_assert_irqs_disabled(); - rcu_nmi_enter_common(true); + rcu_nmi_enter(); } /*
