Commit-ID: 6136d6e48a0138f6be5bb3427dbeb0ba07a546a4 Gitweb: https://git.kernel.org/tip/6136d6e48a0138f6be5bb3427dbeb0ba07a546a4 Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> AuthorDate: Tue, 3 Oct 2017 08:28:04 -0700 Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> CommitDate: Mon, 27 Nov 2017 08:40:10 -0800 rcu: Clamp ->dynticks_nmi_nesting at eqs entry/exit In preparation for merging dyntick-idle irq handling into the NMI algorithm, clamp ->dynticks_nmi_nesting value to allow for interrupts that enter but never leave and vice versa. It is important that the clamping happen outside of the extended quiescent state. Otherwise, there will be short windows where irqs and NMIs fail to convince RCU to start watching. Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> --- kernel/rcu/rcu.h | 2 ++ kernel/rcu/tree.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 59c471d..f4a4119 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -56,6 +56,8 @@ #define DYNTICK_TASK_EXIT_IDLE (DYNTICK_TASK_NEST_VALUE + \ DYNTICK_TASK_FLAG) +#define DYNTICK_IRQ_NONIDLE ((INT_MAX / 2) + 1) + /* * Grace-period counter management. diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 419f3c3..142cdd4 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -818,6 +818,7 @@ static void rcu_eqs_enter(bool user) struct rcu_dynticks *rdtp; rdtp = this_cpu_ptr(&rcu_dynticks); + WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0); if ((rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE) @@ -1008,6 +1009,7 @@ static void rcu_eqs_exit(bool user) rcu_eqs_exit_common(DYNTICK_TASK_EXIT_IDLE, user); rdtp->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE; __this_cpu_dec(disable_rcu_irq_enter); + WRITE_ONCE(rdtp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE); } } -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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