Patch-mainline: v5.6-rc3
Git-commit: 8645e56a4ad6dcbf504872db7f14a2f67db88ef2
References: bsc#1065600
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 19 Feb 2020 18:30:26 +0100
Subject: [PATCH] xen: Enable interrupts when calling _cond_resched()
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>
---
drivers/xen/preempt.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
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);
}
}
--
2.16.4