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 201753FB10 for ; Mon, 22 Jan 2024 18:28:51 +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=1705948133; cv=none; b=PZrW5kAIhdzKQIn83q9QyhzI6GZH487SphZeD0II4fW8/eK/xatBUI7b0o5sEPvBJf0W+krgKowkmK90Rpuc9I+UGvcuC6UpERGK5wStRVUKttOY1EYReGogBfrO1htN494sKO05CpnczvOtElvvcN3/nUDnYK59F8aPvKSr88o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705948133; c=relaxed/simple; bh=Gxrj3RinyAwxp2VAysXILL2r0IZ3ZCqP9A9eSM4h23E=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=IBU2qH5YBb7Wwtjg9DhJxs7q1yhKH1VkTKmbqolxJu1fSn+c2X+25ttcrSyxIJwPIQoqn7BU/gVRAkigohPvaFEUXWbldGM/ZKkdoh2SYKZOjbRenjlTwRgJB7oR0r8u4JgeOD/SSnJi7yDhabcopqsFMeMTyNgSYOTqPVlaSZo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QmoNOs/z; 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="QmoNOs/z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 71B30C433F1; Mon, 22 Jan 2024 18:28:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1705948131; bh=Gxrj3RinyAwxp2VAysXILL2r0IZ3ZCqP9A9eSM4h23E=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=QmoNOs/ztgu28QIu02gqNCUN+QCbxFQOjLSe7TpvTQHUnTsPFBfnlFU/gleJ6CGTQ 9oblOkAG8FZrvahatFuwClhStrAdCTegoS+L9szYspxwd0iU37SYvwaRBRv6CLN3zL Y2t0/tnuNH9RHi6GP9QCUOXxwZ09baT771jgFZo1BKrefgS/idyKASFpt8pIY/Uwdv u584lAxeggWvEWB1QjuQ0Vb9Qo7L7q7HFPT5zyaJr3Q8JF/ZipfnTy7F9Qj+06UNWx 9HKmJC+74CORyKH7tlTQONfysHe29IyksCrQeuqEj9WjXWYQsh4uYWRoqkP6SyxX2S r+bb0tSbpZljw== Date: Mon, 22 Jan 2024 12:28:49 -0600 From: Bjorn Helgaas To: Dan Carpenter Cc: bhelgaas@google.com, linux-pci@vger.kernel.org, Johan Hovold , Kai-Heng Feng Subject: Re: [bug report] Revert "PCI/ASPM: Remove pcie_aspm_pm_state_change()" Message-ID: <20240122182849.GA277265@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <29ee741c-7fbd-4061-87c6-c4ae46c372c1@moroto.mountain> [+cc Johan, Kai-Heng] On Mon, Jan 22, 2024 at 05:43:09PM +0300, Dan Carpenter wrote: > Hello Bjorn Helgaas, > > The patch f93e71aea6c6: "Revert "PCI/ASPM: Remove > pcie_aspm_pm_state_change()"" from Jan 1, 2024 (linux-next), leads to > the following Smatch static checker warning: > > drivers/pci/pcie/aspm.c:1017 pcie_aspm_pm_state_change() > warn: sleeping in atomic context Thanks Dan, this is probably related to the lockdep issue Johan reported here: https://lore.kernel.org/r/ZZu0qx2cmn7IwTyQ@hovoldconsulting.com This is definitely an open issue that should be resolved. Bjorn > drivers/pci/pcie/aspm.c > 1007 void pcie_aspm_pm_state_change(struct pci_dev *pdev) > 1008 { > 1009 struct pcie_link_state *link = pdev->link_state; > 1010 > 1011 if (aspm_disabled || !link) > 1012 return; > 1013 /* > 1014 * Devices changed PM state, we should recheck if latency > 1015 * meets all functions' requirement > 1016 */ > --> 1017 down_read(&pci_bus_sem); > > This is a revert from a patch from 2022 which was before I had written > this "sleeping in atomic" static checker thing. > > 1018 mutex_lock(&aspm_lock); > 1019 pcie_update_aspm_capable(link->root); > 1020 pcie_config_aspm_path(link); > 1021 mutex_unlock(&aspm_lock); > 1022 up_read(&pci_bus_sem); > 1023 } > > The call trees that Smatch is complaining about are: > > vortex_boomerang_interrupt() <- disables preempt > -> _vortex_interrupt() > -> _boomerang_interrupt() > -> vortex_error() > -> vortex_up() > velocity_suspend() <- disables preempt > -> velocity_set_power_state() > -> pci_set_power_state() > -> pci_set_low_power_state() > -> pcie_aspm_pm_state_change() > > So what Smatch is saying is the vortex_boomerang_interrupt() and > velocity_suspend() hold spin locks and then set the power state. The > call trees are quite long so I'm not really able to be sure if this is > a false positive or not... I wish this warning were more useful. > > These emails are a one time thing. Just reply if it's a false positive > and I'll note it down. Otherwise feel free to ignore it. > > regards, > dan carpenter