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From: Thomas Gleixner <tglx@linutronix.de>
To: "Jürgen Groß" <jgross@suse.com>, LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	xen-devel@lists.xenproject.org
Subject: [PATCH V2] xen: Enable interrupts when calling _cond_resched()
Date: Wed, 19 Feb 2020 18:30:26 +0100	[thread overview]
Message-ID: <878skypjrh.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <87h7zmpr1k.fsf@nanos.tec.linutronix.de>

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>
---
V2: Put local_irq_disable() where it belongs.
---
 drivers/xen/preempt.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/xen/preempt.c
+++ b/drivers/xen/preempt.c
@@ -33,7 +33,9 @@ asmlinkage __visible void xen_maybe_pree
 		 * 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);
 	}
 }

WARNING: multiple messages have this Message-ID
From: Thomas Gleixner <tglx@linutronix.de>
To: "Jürgen Groß" <jgross@suse.com>, LKML <linux-kernel@vger.kernel.org>
Cc: xen-devel@lists.xenproject.org,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	x86@kernel.org, Stefano Stabellini <sstabellini@kernel.org>
Subject: [Xen-devel] [PATCH V2] xen: Enable interrupts when calling _cond_resched()
Date: Wed, 19 Feb 2020 18:30:26 +0100	[thread overview]
Message-ID: <878skypjrh.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <87h7zmpr1k.fsf@nanos.tec.linutronix.de>

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>
---
V2: Put local_irq_disable() where it belongs.
---
 drivers/xen/preempt.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/xen/preempt.c
+++ b/drivers/xen/preempt.c
@@ -33,7 +33,9 @@ asmlinkage __visible void xen_maybe_pree
 		 * 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);
 	}
 }

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  reply	other threads:[~2020-02-19 17:30 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-19 11:01 [PATCH] " Thomas Gleixner
2020-02-19 11:01 ` [Xen-devel] " Thomas Gleixner
2020-02-19 12:02 ` Jürgen Groß
2020-02-19 12:02   ` [Xen-devel] " Jürgen Groß
2020-02-19 14:53   ` Thomas Gleixner
2020-02-19 14:53     ` [Xen-devel] " Thomas Gleixner
2020-02-19 17:30     ` Thomas Gleixner [this message]
2020-02-19 17:30       ` [Xen-devel] [PATCH V2] " Thomas Gleixner
2020-02-19 18:42       ` Jürgen Groß
2020-02-19 18:42         ` [Xen-devel] " Jürgen Groß

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