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Wed, 18 Feb 2026 14:20:14 +0000 (GMT) From: Heiko Carstens To: Frederic Weisbecker , Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: [PATCH 7/9] s390/vtime: Use __this_cpu_read() / get rid of READ_ONCE() Date: Wed, 18 Feb 2026 15:20:10 +0100 Message-ID: <20260218142012.863464-8-hca@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260218142012.863464-1-hca@linux.ibm.com> References: <20260218142012.863464-1-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=E+/AZKdl c=1 sm=1 tr=0 ts=6995caa2 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=HzLeVaNsDn8A:10 a=VkNPw1HP01LnGYTKEx00:22 a=Mpw57Om8IfrbqaoTuvik:22 a=GgsMoib0sEa3-_RKJdDe:22 a=VnNF1IyMAAAA:8 a=U-gbc-jHn7uRwbEksAQA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjE4MDEyMCBTYWx0ZWRfXwVmiwHADooC5 UUS9zNXESL2NXS/evT7xDmqeARf6DN/OpcvRpfz4VlmrQHJml71FvsBE7o6+eZ9TQeevPYhvZ9d p24wsA2rKMFtJbAg1MM1HIZ1gsDOROb89ft1CNwBZTM3/qU5LNYyBe7XFOKhEgWVxCigqAwVA99 C0m0irldVFC3s8Wein8bAc0R+RAhDLk7tFnYKypFpgRZ0+pjTv40WzS/gPNiOJZJYiNtc11zEhl J4aGVLu1QwZsQJbxBAS5+XW6fTBOKcFIafuSCEynDnY04JlYxz+TLyfhGa7G+xbWRyQP7FSdHiT QimbF4dKtCVEOy4Qd8+5wW/kNlqewr3Sz30kSYbOXfWpERhTnwtFVTQmGEl2jBV0BrpxsgOm0wG wTUxI0Vd2+yVCdFjNn/gp0rP+DreFWd02VLhyvHFeptxfrcht0b2fsFLucMr8up4u3Zic+4ui0Z AthhQyhritcJ9svCncA== X-Proofpoint-ORIG-GUID: ef6QU2xgt0J1G4jBBOP85CrnfxCZuCvC X-Proofpoint-GUID: ef6QU2xgt0J1G4jBBOP85CrnfxCZuCvC X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-02-18_02,2026-02-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 priorityscore=1501 malwarescore=0 phishscore=0 bulkscore=0 suspectscore=0 spamscore=0 clxscore=1015 impostorscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2602180120 do_account_vtime() runs always with interrupts disabled, therefore use __this_cpu_read() instead of this_cpu_read() to get rid of a pointless preempt_disable() / preempt_enable() pair. Also there are no concurrent writers to the cpu time accounting fields in lowcore. Therefore get rid of READ_ONCE() usages. Signed-off-by: Heiko Carstens --- arch/s390/kernel/vtime.c | 21 +++++++-------------- 1 file changed, 7 insertions(+), 14 deletions(-) diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c index 122d30b10440..4111ff4d727c 100644 --- a/arch/s390/kernel/vtime.c +++ b/arch/s390/kernel/vtime.c @@ -137,23 +137,16 @@ static int do_account_vtime(struct task_struct *tsk) lc->system_timer += timer; /* Update MT utilization calculation */ - if (smp_cpu_mtid && - time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies))) + if (smp_cpu_mtid && time_after64(jiffies_64, __this_cpu_read(mt_scaling_jiffies))) update_mt_scaling(); /* Calculate cputime delta */ - user = update_tsk_timer(&tsk->thread.user_timer, - READ_ONCE(lc->user_timer)); - guest = update_tsk_timer(&tsk->thread.guest_timer, - READ_ONCE(lc->guest_timer)); - system = update_tsk_timer(&tsk->thread.system_timer, - READ_ONCE(lc->system_timer)); - hardirq = update_tsk_timer(&tsk->thread.hardirq_timer, - READ_ONCE(lc->hardirq_timer)); - softirq = update_tsk_timer(&tsk->thread.softirq_timer, - READ_ONCE(lc->softirq_timer)); - lc->steal_timer += - clock - user - guest - system - hardirq - softirq; + user = update_tsk_timer(&tsk->thread.user_timer, lc->user_timer); + guest = update_tsk_timer(&tsk->thread.guest_timer, lc->guest_timer); + system = update_tsk_timer(&tsk->thread.system_timer, lc->system_timer); + hardirq = update_tsk_timer(&tsk->thread.hardirq_timer, lc->hardirq_timer); + softirq = update_tsk_timer(&tsk->thread.softirq_timer, lc->softirq_timer); + lc->steal_timer += clock - user - guest - system - hardirq - softirq; /* Push account value */ if (user) { -- 2.51.0