linux-kernel - [PATCH v2] locking/pvqspinlock: Wait early if vCPU is preempted

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1484035006-6787-1-git-send-email-xinhui.pan@linux.vnet.ibm.com>
Date:   Tue, 10 Jan 2017 02:56:46 -0500
From:   Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...hat.com, peterz@...radead.org, longman@...hat.com,
        Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>
Subject: [PATCH v2] locking/pvqspinlock: Wait early if vCPU is preempted

If prev node is not in runnig state or its vCPU is preempted, we can give
up our vCPU slices ASAP in pv_wait_node. After commit d9345c65eb79
("sched/core: Introduce the vcpu_is_preempted(cpu) interface") kernel
has knowledge of one vCPU is running or not.

Signed-off-by: Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>
---
v2:
  rewrite the commit message as Ingo pointed out the mistake.
---
 kernel/locking/qspinlock_paravirt.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
index e3b5520..48648dc 100644
--- a/kernel/locking/qspinlock_paravirt.h
+++ b/kernel/locking/qspinlock_paravirt.h
@@ -263,7 +263,8 @@ pv_wait_early(struct pv_node *prev, int loop)
 	if ((loop & PV_PREV_CHECK_MASK) != 0)
 		return false;
 
-	return READ_ONCE(prev->state) != vcpu_running;
+	return READ_ONCE(prev->state) != vcpu_running ||
+				vcpu_is_preempted(prev->cpu);
 }
 
 /*
-- 
2.4.11