Release 4.7 drivers/xen/preempt.c

/*
 * Preemptible hypercalls
 *
 * Copyright (C) 2014 Citrix Systems R&D ltd.
 *
 * This source code is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 */

#include <linux/sched.h>
#include <xen/xen-ops.h>

#ifndef CONFIG_PREEMPT

/*
 * Some hypercalls issued by the toolstack can take many 10s of
 * seconds. Allow tasks running hypercalls via the privcmd driver to
 * be voluntarily preempted even if full kernel preemption is
 * disabled.
 *
 * Such preemptible hypercalls are bracketed by
 * xen_preemptible_hcall_begin() and xen_preemptible_hcall_end()
 * calls.
 */

DEFINE_PER_CPU(bool, xen_in_preemptible_hcall);

EXPORT_SYMBOL_GPL(xen_in_preemptible_hcall);



asmlinkage __visible void xen_maybe_preempt_hcall(void)
{
	if (unlikely(__this_cpu_read(xen_in_preemptible_hcall)
		     && need_resched())) {
		/*
                 * Clear flag as we may be rescheduled on a different
                 * cpu.
                 */
		__this_cpu_write(xen_in_preemptible_hcall, false);
		_cond_resched();
		__this_cpu_write(xen_in_preemptible_hcall, true);
	}
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
david vrabel
david vrabel
41
97.62%
1
50.00%
konstantin khlebnikov
konstantin khlebnikov
1
2.38%
1
50.00%
Total
42
100.00%
2
100.00%

#endif /* CONFIG_PREEMPT */
Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
david vrabel
david vrabel
67
98.53%
1
50.00%
konstantin khlebnikov
konstantin khlebnikov
1
1.47%
1
50.00%
Total
68
100.00%
2
100.00%
  
Directory: drivers/xen

Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.