From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.136]:41068 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752660AbbLCRVb (ORCPT ); Thu, 3 Dec 2015 12:21:31 -0500 Date: Thu, 3 Dec 2015 11:21:28 -0600 From: Bjorn Helgaas To: Andy Lutomirski Cc: Matthew Garrett , Bjorn Helgaas , linux-pci@vger.kernel.org Subject: Re: [PATCH] pcie_aspm: Make link_state_store consistent with link_state_show Message-ID: <20151203172128.GA17565@localhost> References: <6ff64f0313c4e6400ef536017078e58ec3487c71.1447949082.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <6ff64f0313c4e6400ef536017078e58ec3487c71.1447949082.git.luto@kernel.org> Sender: linux-pci-owner@vger.kernel.org List-ID: On Thu, Nov 19, 2015 at 08:05:35AM -0800, Andy Lutomirski wrote: > If CONFIG_PCIEASPM_DEBUG is set, then pci devices have a link_state > attribute. Reading that attribute shows the state as a bit mask: 1 > means L0S upstream, 2 means L0S downstream, and 4 means L1. > > Oddly, writing to link_state is inconsistent and gets translated, > leading to mysterious results in which the value you store isn't > comparable the value you load back out. > > Fix it by making link_state_store match link_state_show. > > Signed-off-by: Andy Lutomirski Applied to pci/aspm for v4.5, thanks! You didn't touch the "aspm_disabled" check, but I moved it above the input validation code to make the patch look like the attached. I think it's better to not even look at the input if aspm_disabled, and this also puts the validation code all together. Let me know if you object. Bjorn commit 57d86a0485a30145382ad03b9504cc03ba4641c7 Author: Andy Lutomirski Date: Thu Nov 19 08:05:35 2015 -0800 PCI/ASPM: Make sysfs link_state_store() consistent with link_state_show() If CONFIG_PCIEASPM_DEBUG is set, then PCI devices have a link_state attribute. Reading that attribute shows the state as a bit mask: 1 means L0S upstream, 2 means L0S downstream, and 4 means L1. Oddly, writing to link_state is inconsistent and gets translated, leading to mysterious results in which the value you store isn't comparable the value you load back out. Fix it by making link_state_store() match link_state_show(). [bhelgaas: Check "aspm_disabled" *before* validating input. When "aspm_disabled" is set, this changes the error for invalid input from -EINVAL to -EPERM.] Signed-off-by: Andy Lutomirski Signed-off-by: Bjorn Helgaas diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 317e355..2dfe7fd 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -834,21 +834,15 @@ static ssize_t link_state_store(struct device *dev, { struct pci_dev *pdev = to_pci_dev(dev); struct pcie_link_state *link, *root = pdev->link_state->root; - u32 val, state = 0; - - if (kstrtouint(buf, 10, &val)) - return -EINVAL; + u32 state; if (aspm_disabled) return -EPERM; - if (n < 1 || val > 3) - return -EINVAL; - /* Convert requested state to ASPM state */ - if (val & PCIE_LINK_STATE_L0S) - state |= ASPM_STATE_L0S; - if (val & PCIE_LINK_STATE_L1) - state |= ASPM_STATE_L1; + if (kstrtouint(buf, 10, &state)) + return -EINVAL; + if ((state & ~ASPM_STATE_ALL) != 0) + return -EINVAL; down_read(&pci_bus_sem); mutex_lock(&aspm_lock);