From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755061AbcI2NLf (ORCPT ); Thu, 29 Sep 2016 09:11:35 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:45435 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753332AbcI2NL0 (ORCPT ); Thu, 29 Sep 2016 09:11:26 -0400 Date: Thu, 29 Sep 2016 15:11:16 +0200 From: Martin Schwidefsky To: Christian Borntraeger Cc: Peter Zijlstra , Heiko Carstens , Pan Xinhui , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, xen-devel-request@lists.xenproject.org, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, mingo@redhat.com, paulmck@linux.vnet.ibm.com, will.deacon@arm.com, kernellwp@gmail.com, jgross@suse.com, pbonzini@redhat.com, bsingharora@gmail.com Subject: Re: [PATCH] s390x/spinlock: Provide vcpu_is_preempted globally In-Reply-To: <1475150056-58774-1-git-send-email-borntraeger@de.ibm.com> References: <1475150056-58774-1-git-send-email-borntraeger@de.ibm.com> X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.23; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16092913-0028-0000-0000-000002263347 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16092913-0029-0000-0000-000020A09D29 Message-Id: <20160929151116.3b5e8f07@mschwide> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-09-29_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609020000 definitions=main-1609290230 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 29 Sep 2016 13:54:16 +0200 Christian Borntraeger wrote: > this implements the s390 backend for commit > "kernel/sched: introduce vcpu preempted check interface" > by simply reusing the existing cpu_is_preempted function. > > Signed-off-by: Christian Borntraeger > --- > Martin, Heiko, > > this patch is a minimal change by not touching all existing users of > cpu_is_preempted in spinlock.c. If you want it differently, let me > know. > > > arch/s390/include/asm/spinlock.h | 7 +++++++ > arch/s390/lib/spinlock.c | 3 ++- > 2 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/arch/s390/include/asm/spinlock.h b/arch/s390/include/asm/spinlock.h > index 63ebf37..6e82986 100644 > --- a/arch/s390/include/asm/spinlock.h > +++ b/arch/s390/include/asm/spinlock.h > @@ -21,6 +21,13 @@ _raw_compare_and_swap(unsigned int *lock, unsigned int old, unsigned int new) > return __sync_bool_compare_and_swap(lock, old, new); > } > > +int arch_vcpu_is_preempted(int cpu); > +#define vcpu_is_preempted cpu_is_preempted > +static inline bool cpu_is_preempted(int cpu) > +{ > + return arch_vcpu_is_preempted(cpu); > +} > + > /* > * Simple spin lock operations. There are two variants, one clears IRQ's > * on the local processor, one does not. > diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c > index e5f50a7..9f473c8 100644 > --- a/arch/s390/lib/spinlock.c > +++ b/arch/s390/lib/spinlock.c > @@ -37,7 +37,7 @@ static inline void _raw_compare_and_delay(unsigned int *lock, unsigned int old) > asm(".insn rsy,0xeb0000000022,%0,0,%1" : : "d" (old), "Q" (*lock)); > } > > -static inline int cpu_is_preempted(int cpu) > +int arch_vcpu_is_preempted(int cpu) > { > if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu)) > return 0; > @@ -45,6 +45,7 @@ static inline int cpu_is_preempted(int cpu) > return 0; > return 1; > } > +EXPORT_SYMBOL(arch_vcpu_is_preempted); > > void arch_spin_lock_wait(arch_spinlock_t *lp) > { Hmm, if I look at the code we now have an additional function for the spinlock loops. The call arch_vcpu_is_preempted which test CIF_ENABLED_WAIT and then calls smp_vcpu_scheduled(). The test used to be inline. A better solution would be to move the CIF_ENABLED_WAIT test to the smp_vcpu_scheduled() function, rename it to arch_vcpu_is_preempted() and then export that function. The cpu_is_preempted() function is replaced by arch_vcpu_is_preempted() which does make a lot of sense, no? -- blue skies, Martin. "Reality continues to ruin my life." - Calvin.