From nobody Tue Dec 2 01:05:43 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 468313043C8; Fri, 21 Nov 2025 20:01:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763755295; cv=none; b=SI4/9JS4Ve31jEom8e5NTACIlawAzaJQAR74i2TqIFGslrnpPLEMmB587ixQuID1HjU3VKfT496oGlcuC6JdXG/x/4fJK+d4UHcGstf6/QhnKppklC09pXiZKG+dvyU9ZOu2De4HLscin8hb6QCgMwFVr3VSrJvSo7jQS8aFxnc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763755295; c=relaxed/simple; bh=wCG4IVi/C2NerX0Z0NhFPtGBXqwuiQpJNX6PV7S+Slc=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=X+AfHvUghz084LKxpm4uwmKspnGaFBk3VBKsUrAco5avK8gBpEooVPYx5DBWADuh72hcpVB+/9FzOEkgJnHP4IY43wcE0zP487wJTf4kILhy803A/FnjhxllxO/llXKjAq5/zDBrDHzCOUUgvxFmzV/k/WhhzaMVnBGT/g891q0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=ED5MrfU/; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=xY+4NOkR; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="ED5MrfU/"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="xY+4NOkR" Date: Fri, 21 Nov 2025 20:01:30 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1763755291; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=NhgU0wsElUfBi18xQStQyCzzCKuKIzisHjE6zpHMqXk=; b=ED5MrfU/VgIqwWEPJnz/kPplLP+cL2xFPLR7pncwTV1NiFGoyITijyupp9pNylaNCKfTix USJehqmhx9oersxpehVjd9A21FtPzDSvkHHIhxrVncwebzFFIguGskcRm5FDo3jgBm4PgQ SdwD/qFR5K9W/hqp2WnKkHPn7ef7Wm2QRCDmgQIghgGqBDmHuH0o76XpF9AY9+altDxSQM hc6rYJYKYTH2YuRGulp/bMbx3fRO5+znjkr8Wff9aXsznKS6wOS1q/rYGDCQKt8cCefnw9 sf30+9gQ24lL0NiFtLWNy5pOuWPXNEE31rblpplvgr3RxiZ3TP5naOYZgBY37w== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1763755291; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=NhgU0wsElUfBi18xQStQyCzzCKuKIzisHjE6zpHMqXk=; b=xY+4NOkR2DfUj/Owqp5yxKogTP8RIeLGjc99J1IYBly5FOkINENcdixmMSrBOt+59OSpnD WvYGMy0kcACNLrDA== From: "tip-bot2 for Thomas Gleixner" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: irq/core] genirq: Prevent early spurious wake-ups of interrupt threads Cc: Frederic Weisbecker , Thomas Gleixner , x86@kernel.org, linux-kernel@vger.kernel.org, maz@kernel.org In-Reply-To: <20251121143500.42111-2-frederic@kernel.org> References: <20251121143500.42111-2-frederic@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <176375529017.498.4701344518061876052.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the irq/core branch of tip: Commit-ID: 9d5ca2edd74e479ad09bc7d02820395a9d46e2bd Gitweb: https://git.kernel.org/tip/9d5ca2edd74e479ad09bc7d02820395a9= d46e2bd Author: Thomas Gleixner AuthorDate: Fri, 21 Nov 2025 15:34:58 +01:00 Committer: Thomas Gleixner CommitterDate: Fri, 21 Nov 2025 20:50:30 +01:00 genirq: Prevent early spurious wake-ups of interrupt threads During initialization, the interrupt thread is created before the interrupt is enabled. The interrupt enablement happens before the actual kthread wake up point. Once the interrupt is enabled the hardware can raise an interrupt and once setup_irq() drops the descriptor lock a interrupt wake-up can happen. Even when such an interrupt can be considered premature, this is not a problem in general because at the point where the descriptor lock is dropped and the wakeup can happen, the data which is used by the thread is fully initialized. Though from the perspective of least surprise, the initial wakeup really should be performed by the setup code and not randomly by a premature interrupt. Prevent this by performing a wake-up only if the target is in state TASK_INTERRUPTIBLE, which the thread uses in wait_for_interrupt(). If the thread is still in state TASK_UNINTERRUPTIBLE, the wake-up is not lost because after the setup code completed the initial wake-up the thread will observe the IRQTF_RUNTHREAD and proceed with the handling. Signed-off-by: Frederic Weisbecker Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20251121143500.42111-2-frederic@kernel.org --- kernel/irq/handle.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c index e103451..786f557 100644 --- a/kernel/irq/handle.c +++ b/kernel/irq/handle.c @@ -133,7 +133,15 @@ void __irq_wake_thread(struct irq_desc *desc, struct i= rqaction *action) */ atomic_inc(&desc->threads_active); =20 - wake_up_process(action->thread); + /* + * This might be a premature wakeup before the thread reached the + * thread function and set the IRQTF_READY bit. It's waiting in + * kthread code with state UNINTERRUPTIBLE. Once it reaches the + * thread function it waits with INTERRUPTIBLE. The wakeup is not + * lost in that case because the thread is guaranteed to observe + * the RUN flag before it goes to sleep in wait_for_interrupt(). + */ + wake_up_state(action->thread, TASK_INTERRUPTIBLE); } =20 static DEFINE_STATIC_KEY_FALSE(irqhandler_duration_check_enabled);