Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755983Ab3IYWOn (ORCPT ); Wed, 25 Sep 2013 18:14:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:16654 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752428Ab3IYWOl (ORCPT ); Wed, 25 Sep 2013 18:14:41 -0400 Date: Thu, 26 Sep 2013 00:12:50 +0200 From: Veaceslav Falico To: Bjorn Helgaas Cc: "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" Subject: Re: [PATCH 3/3] msi: free msi_desc entry only after we've released the kobject Message-ID: <20130925221250.GB26965@redhat.com> References: <1379382464-7920-1-git-send-email-vfalico@redhat.com> <1379382464-7920-4-git-send-email-vfalico@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4365 Lines: 119 On Wed, Sep 25, 2013 at 03:34:58PM -0600, Bjorn Helgaas wrote: >On Mon, Sep 16, 2013 at 7:47 PM, Veaceslav Falico wrote: >> Currently, we first do kobject_put(&entry->kobj) and the kfree(entry), >> however kobject_put() doesn't guarantee us that it was the last reference >> and that the kobj isn't used currently by someone else, so after we >> kfree(entry) with the struct kobject - other users will begin using the >> freed memory, instead of the actual kobject. >> >> Fix this by using the kobject->release callback, which is called last when >> the kobject is indeed not used and is cleaned up - it's msi_kobj_release(), >> which can do the kfree(entry) safely (kobject_put/cleanup doesn't use the >> kobj itself after ->release() was called, so we're safe). >> >> In case we've failed to create the sysfs directories - just kfree() >> it - cause we don't have the kobjects attached. >> >> Also, remove the same functionality from populate_msi_sysfs(), cause on >> failure we anyway call free_msi_irqs(), which will take care of all the >> kobjects properly. > >I agree; it looks like populate_msi_sysfs() doesn't need to have the >cleanup in it. Can you split that into a separate patch, since I >don't think it depends on the kfree() fix? Yep, will do and re-send in two patchsets. Thank you! > >Bjorn > >> CC: Bjorn Helgaas >> CC: linux-pci@vger.kernel.org >> CC: linux-kernel@vger.kernel.org >> Signed-off-by: Veaceslav Falico >> --- >> drivers/pci/msi.c | 27 +++++++++------------------ >> 1 file changed, 9 insertions(+), 18 deletions(-) >> >> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c >> index 68da921..c9236e4 100644 >> --- a/drivers/pci/msi.c >> +++ b/drivers/pci/msi.c >> @@ -374,19 +374,22 @@ static void free_msi_irqs(struct pci_dev *dev) >> iounmap(entry->mask_base); >> } >> >> + list_del(&entry->list); >> + >> /* >> * Its possible that we get into this path >> * When populate_msi_sysfs fails, which means the entries >> * were not registered with sysfs. In that case don't >> - * unregister them. >> + * unregister them, and just free. Otherwise the >> + * kobject->release will take care of freeing the entry via >> + * msi_kobj_release(). >> */ >> if (entry->kobj.parent) { >> kobject_del(&entry->kobj); >> kobject_put(&entry->kobj); >> + } else { >> + kfree(entry); >> } >> - >> - list_del(&entry->list); >> - kfree(entry); >> } >> >> kset_unregister(dev->msi_kset); >> @@ -512,6 +515,7 @@ static void msi_kobj_release(struct kobject *kobj) >> struct msi_desc *entry = to_msi_desc(kobj); >> >> pci_dev_put(entry->dev); >> + kfree(entry); >> } >> >> static struct kobj_type msi_irq_ktype = { >> @@ -525,7 +529,6 @@ static int populate_msi_sysfs(struct pci_dev *pdev) >> struct msi_desc *entry; >> struct kobject *kobj; >> int ret; >> - int count = 0; >> >> pdev->msi_kset = kset_create_and_add("msi_irqs", NULL, &pdev->dev.kobj); >> if (!pdev->msi_kset) >> @@ -539,23 +542,11 @@ static int populate_msi_sysfs(struct pci_dev *pdev) >> "%u", entry->irq); >> if (ret) { >> pci_dev_put(pdev); >> - goto out_unroll; >> + return ret; >> } >> - >> - count++; >> } >> >> return 0; >> - >> -out_unroll: >> - list_for_each_entry(entry, &pdev->msi_list, list) { >> - if (!count) >> - break; >> - kobject_del(&entry->kobj); >> - kobject_put(&entry->kobj); >> - count--; >> - } >> - return ret; >> } >> >> /** >> -- >> 1.8.4 >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/