| From 2e74bd3839475fdf86250e83ffd484f646204876 Mon Sep 17 00:00:00 2001 |
| From: Thomas Gleixner <tglx@linutronix.de> |
| Date: Wed, 19 Feb 2020 18:30:26 +0100 |
| Subject: [PATCH] xen: Enable interrupts when calling _cond_resched() |
| |
| commit 8645e56a4ad6dcbf504872db7f14a2f67db88ef2 upstream. |
| |
| xen_maybe_preempt_hcall() is called from the exception entry point |
| xen_do_hypervisor_callback with interrupts disabled. |
| |
| _cond_resched() evades the might_sleep() check in cond_resched() which |
| would have caught that and schedule_debug() unfortunately lacks a check |
| for irqs_disabled(). |
| |
| Enable interrupts around the call and use cond_resched() to catch future |
| issues. |
| |
| Fixes: fdfd811ddde3 ("x86/xen: allow privcmd hypercalls to be preempted") |
| Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
| Link: https://lore.kernel.org/r/878skypjrh.fsf@nanos.tec.linutronix.de |
| Reviewed-by: Juergen Gross <jgross@suse.com> |
| Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/xen/preempt.c b/drivers/xen/preempt.c |
| index 8b9919c26095..456a164364a2 100644 |
| --- a/drivers/xen/preempt.c |
| +++ b/drivers/xen/preempt.c |
| @@ -33,7 +33,9 @@ asmlinkage __visible void xen_maybe_preempt_hcall(void) |
| * cpu. |
| */ |
| __this_cpu_write(xen_in_preemptible_hcall, false); |
| - _cond_resched(); |
| + local_irq_enable(); |
| + cond_resched(); |
| + local_irq_disable(); |
| __this_cpu_write(xen_in_preemptible_hcall, true); |
| } |
| } |
| -- |
| 2.7.4 |
| |