Commit 1de16e0c authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/entry: Split out idtentry_exit_cond_resched() 



The XEN PV hypercall requires the ability of conditional rescheduling when
preemption is disabled because some hypercalls take ages.

Split out the rescheduling code from idtentry_exit_cond_rcu() so it can
be reused for that.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20200521202117.962199649@linutronix.de
parent eb6555c8

arch/x86/entry/common.c

+15 −15
Original line number Diff line number Diff line
@@ -583,6 +583,20 @@ bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs) 
	return false;

}



static void idtentry_exit_cond_resched(struct pt_regs *regs, bool may_sched)

{

	if (may_sched && !preempt_count()) {

		/* Sanity check RCU and thread stack */

		rcu_irq_exit_check_preempt();

		if (IS_ENABLED(CONFIG_DEBUG_ENTRY))

			WARN_ON_ONCE(!on_thread_stack());

		if (need_resched())

			preempt_schedule_irq();

	}

	/* Covers both tracing and lockdep */

	trace_hardirqs_on();

}



/**

 * idtentry_exit_cond_rcu - Handle return from exception with conditional RCU

 *			    handling
@@ -624,21 +638,7 @@ void noinstr idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit) 
		}



		instrumentation_begin();



		/* Check kernel preemption, if enabled */

		if (IS_ENABLED(CONFIG_PREEMPTION)) {

			if (!preempt_count()) {

				/* Sanity check RCU and thread stack */

				rcu_irq_exit_check_preempt();

				if (IS_ENABLED(CONFIG_DEBUG_ENTRY))

					WARN_ON_ONCE(!on_thread_stack());

				if (need_resched())

					preempt_schedule_irq();

			}

		}

		/* Covers both tracing and lockdep */

		trace_hardirqs_on();



		idtentry_exit_cond_resched(regs, IS_ENABLED(CONFIG_PREEMPTION));

		instrumentation_end();

	} else {

		/*

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