diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2020-05-03 16:08:52 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-05-19 16:51:21 +0300 |
| commit | 8ae0ae6737ad449c8ae21e2bb01d9736f360a933 (patch) | |
| tree | 1143878ecb15a2eeb6790b837da31d14a96c0776 /kernel/rcu | |
| parent | 9ea366f669ded353ae49754216c042e7d2f72ba6 (diff) | |
| download | linux-8ae0ae6737ad449c8ae21e2bb01d9736f360a933.tar.xz | |
rcu: Provide rcu_irq_exit_preempt()
Interrupts and exceptions invoke rcu_irq_enter() on entry and need to
invoke rcu_irq_exit() before they either return to the interrupted code or
invoke the scheduler due to preemption.
The general assumption is that RCU idle code has to have preemption
disabled so that a return from interrupt cannot schedule. So the return
from interrupt code invokes rcu_irq_exit() and preempt_schedule_irq().
If there is any imbalance in the rcu_irq/nmi* invocations or RCU idle code
had preemption enabled then this goes unnoticed until the CPU goes idle or
some other RCU check is executed.
Provide rcu_irq_exit_preempt() which can be invoked from the
interrupt/exception return code in case that preemption is enabled. It
invokes rcu_irq_exit() and contains a few sanity checks in case that
CONFIG_PROVE_RCU is enabled to catch such issues directly.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134904.364456424@linutronix.de
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 945401674b9d..62ee01299386 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -743,6 +743,28 @@ void noinstr rcu_irq_exit(void) rcu_nmi_exit(); } +/** + * rcu_irq_exit_preempt - Inform RCU that current CPU is exiting irq + * towards in kernel preemption + * + * Same as rcu_irq_exit() but has a sanity check that scheduling is safe + * from RCU point of view. Invoked from return from interrupt before kernel + * preemption. + */ +void rcu_irq_exit_preempt(void) +{ + lockdep_assert_irqs_disabled(); + rcu_nmi_exit(); + + RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) <= 0, + "RCU dynticks_nesting counter underflow/zero!"); + RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) != + DYNTICK_IRQ_NONIDLE, + "Bad RCU dynticks_nmi_nesting counter\n"); + RCU_LOCKDEP_WARN(rcu_dynticks_curr_cpu_in_eqs(), + "RCU in extended quiescent state!"); +} + /* * Wrapper for rcu_irq_exit() where interrupts are enabled. * |