From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D7AF1324B22; Fri, 23 Jan 2026 03:11:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769137909; cv=none; b=CbINqk/cT8hjsikJ5LjGEe077ymtdCYvWAk45jUzuNNh9TzkAmc7wppm8sQKoBYXJr3u7RKBUn8KL6cuXsUkz9YSoVFrBTAcOnwgeOQ5QoI77v17Su1rCIeqAYjdd80LsZySlox2BFt3yRYWmAPhecLARdNpfvvfDaTmuEEgA1s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769137909; c=relaxed/simple; bh=2sduAVtZ4sB8Xd4nr5su39mrxAhJpvtA6zzQa7Mf+Do=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BiZL0RFLMcQCT9CiCAmumCRsMgU9tWVNMbSEaoTYTR8C+Gs1kfqLBE3egXumCumj8Rz/9JkXx7feS22caoS6AAqFyMfbsrSl6urqGdkxD7S/y1wFsP9ipDds8mdPEqhuccIgTijRjN8Ff9UYtaf1+wbG9AngjBhQwHXQwFp4nAI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fj1R0gOL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fj1R0gOL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76D01C116C6; Fri, 23 Jan 2026 03:11:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769137908; bh=2sduAVtZ4sB8Xd4nr5su39mrxAhJpvtA6zzQa7Mf+Do=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fj1R0gOLXQUlFV3n7CSQAixhVa2ZWA18o7kpvaFwNZqp679B28Fi7ZvcfkzlHy8ZL 71LQ2/8l+4ggAMsuaY4KT4up2NbE1UJRc5XJ9OUIo2MSm1Tcr1lqwJ+McFmgRKI7e0 uzD6p7KWyF7iD4CrEzmL9jaLLYyyvB9vKYFywt0wqXSpkkrddkb+PpwLWZ8c8RXeg/ sD3cqqGdPWqz94sNG7VJUI7/e603y0jBa7l57RosrsZtVmiVy+PzH0idRmwA+P+w4h QVjPwnPOVzJhcfQoxxEtBx9BQsM7Cn46HpwTnydgsrfvOy6nir4xY0WaALfgqVYQ0f ir7IyRs7p84LA== From: Jakub Kicinski To: itazur@amazon.com Cc: Jakub Kicinski , graf@amazon.de, itazur@amazon.co.uk, conor+dt@kernel.org, dwmw2@infradead.org, devicetree@vger.kernel.org, xmarcalx@amazon.co.uk, linux-kernel@vger.kernel.org, edumazet@google.com, robh@kernel.org, richardcochran@gmail.com, andrew+netdev@lunn.ch, mzxreary@0pointer.de, pabeni@redhat.com, dwmw@amazon.co.uk, netdev@vger.kernel.org, krzk+dt@kernel.org, davem@davemloft.net, mail@bchalios.io Subject: Re: [v6,2/7] ptp: vmclock: support device notifications Date: Thu, 22 Jan 2026 19:11:34 -0800 Message-ID: <20260123031133.3059291-2-kuba@kernel.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260121143402.3092-3-itazur@amazon.com> References: <20260121143402.3092-3-itazur@amazon.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This is an AI-generated review of your patch. The human sending this email has considered the AI review valid, or at least plausible. For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html --- ptp: vmclock: support device notifications This patch adds optional device notification support to VMClock, allowing the hypervisor to notify the driver when seq_count changes. It also adds poll() support to propagate these notifications to userspace. > diff --git a/drivers/ptp/ptp_vmclock.c b/drivers/ptp/ptp_vmclock.c > index b3a83b03d9c1..38b2bacb755e 100644 > --- a/drivers/ptp/ptp_vmclock.c > +++ b/drivers/ptp/ptp_vmclock.c [ ... ] > +static void > +vmclock_acpi_notification_handler(acpi_handle __always_unused handle, > + u32 __always_unused event, void *dev) > +{ > + struct device *device = dev; > + struct vmclock_state *st = device->driver_data; > + > + wake_up_interruptible(&st->disrupt_wait); > +} > + > +static int vmclock_setup_notification(struct device *dev, struct vmclock_state *st) > +{ [ ... ] > + status = acpi_install_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY, > + vmclock_acpi_notification_handler, > + dev); Since acpi_install_notify_handler() is called here, should there be a corresponding acpi_remove_notify_handler() in vmclock_remove()? Currently the handler remains registered after device removal, which could lead to a use-after-free if the hypervisor sends a notification after the driver state has been freed. [ ... ] > @@ -549,6 +653,11 @@ static int vmclock_probe(struct platform_device *pdev) > if (ret) > return ret; > > + init_waitqueue_head(&st->disrupt_wait); > + ret = vmclock_setup_notification(dev, st); > + if (ret) > + return ret; [ ... ] > @@ -581,6 +690,8 @@ static int vmclock_probe(struct platform_device *pdev) > return -ENODEV; > } > > + dev->driver_data = st; Is there a race window here? The ACPI notification handler is installed in vmclock_setup_notification() which runs earlier in vmclock_probe(), but the handler accesses device->driver_data. If the hypervisor sends a notification between vmclock_setup_notification() and this assignment, vmclock_acpi_notification_handler() would dereference NULL or garbage. I see this is fixed later in the series by commit 47fdd294385e which moves dev->driver_data = st before vmclock_setup_notification(). -- pw-bot: cr