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Wed, 11 Mar 2026 06:17:24 +0000 (GMT) From: Shrikanth Hegde To: linuxppc-dev@lists.ozlabs.org, maddy@linux.ibm.com Cc: sshegde@linux.ibm.com, chleroy@kernel.org, nysal@linux.ibm.com, mkchauras@linux.ibm.com, rafael@kernel.org, daniel.lezcano@kernel.org, christian.loehle@arm.com, mkchauras@gmail.com, npiggin@gmail.com, linux-pm@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v2] cpuidle: powerpc: avoid double clear when breaking snooze Date: Wed, 11 Mar 2026 11:47:09 +0530 Message-ID: <20260311061709.1230440-1-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=ds3Wylg4 c=1 sm=1 tr=0 ts=69b108fc cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=pGLkceISAAAA:8 a=cVrzkdVh9Pqr8fURmIoA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzExMDA0OSBTYWx0ZWRfX5OlTuLCxBycs bsoQQt2MYTPFxkbG+pgCJpHm6FfnYhFm7WQ2aE4LrjClRvwwvtcE+XTQJyLAieMDac4/2tqAJiH KLoVPhxvV5WcI/S2qBVPVyEIr5bvDC5oiDkcq6sJNZdpERMHxXib4rdDSwxWkz5z9jilH1Pdi+e Mf3XiBpkV4Ha+e6N3w2bc4ZtQHugpGFnM5+IaXqnjDQsZ6cHizwXJoVawQkxIIWOH2QaOwteQ/K 2LTKxDDvND7F5d4lNvU31db5x0DUv+6khf5TJMEjGxB7O4QWnyfYCV9yboD2QCG4w1M/06Obf9V fJ7rOJqJct2fNJAkTaEBvOePpWCirvJddfYO+9G7R3S0XRYz0hn/u3tKiq7F/f29cEywnjp/Jl0 qEgxf1CjR+9BoXrOt6LlKs4b9PeQfDVxW3LJe1NjgEd6WXhIiF2lH0hE/gLVTZmP5hPlRyrplIz kbVhZoMlQm2qrbkir9w== X-Proofpoint-GUID: IwXrcu66crhxX1fWNSOJmNmD6fEejyAe X-Proofpoint-ORIG-GUID: KUkcok53n_Viifrr4RsG4gVX4qwPZMwN X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-10_05,2026-03-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 phishscore=0 clxscore=1011 impostorscore=0 suspectscore=0 priorityscore=1501 lowpriorityscore=0 malwarescore=0 adultscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2602130000 definitions=main-2603110049 snooze_loop is done often in any system which has fair bit of idle time. So it qualifies for even micro-optimizations. When breaking the snooze due to timeout, TIF_POLLING_NRFLAG is cleared twice. Clearing the bit invokes atomics. Avoid double clear and thereby avoid one atomic write. dev->poll_time_limit indicates whether the loop was broken due to timeout. Use that instead of defining a new variable. Fixes: 7ded429152e8 ("cpuidle: powerpc: no memory barrier after break from idle") Cc: stable@vger.kernel.org Reviewed-by: Mukesh Kumar Chaurasiya (IBM) Signed-off-by: Shrikanth Hegde --- v1->v2: - Added rwb tag - Thanks to Mukesh Kumar Chaurasiya - Added fixes tag v1: https://lore.kernel.org/all/20260310152811.1131119-1-sshegde@linux.ibm.com/ drivers/cpuidle/cpuidle-powernv.c | 5 ++++- drivers/cpuidle/cpuidle-pseries.c | 5 ++++- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c index 9ebedd972df0..b89e7111e7b8 100644 --- a/drivers/cpuidle/cpuidle-powernv.c +++ b/drivers/cpuidle/cpuidle-powernv.c @@ -95,7 +95,10 @@ static int snooze_loop(struct cpuidle_device *dev, HMT_medium(); ppc64_runlatch_on(); - clear_thread_flag(TIF_POLLING_NRFLAG); + + /* Avoid double clear when breaking */ + if (!dev->poll_time_limit) + clear_thread_flag(TIF_POLLING_NRFLAG); local_irq_disable(); diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c index f68c65f1d023..864dd5d6e627 100644 --- a/drivers/cpuidle/cpuidle-pseries.c +++ b/drivers/cpuidle/cpuidle-pseries.c @@ -64,7 +64,10 @@ int snooze_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv, } HMT_medium(); - clear_thread_flag(TIF_POLLING_NRFLAG); + + /* Avoid double clear when breaking */ + if (!dev->poll_time_limit) + clear_thread_flag(TIF_POLLING_NRFLAG); raw_local_irq_disable(); -- 2.43.0