From patchwork Tue Oct 27 21:05:15 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 536896 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id A576F141372; Wed, 28 Oct 2015 08:05:58 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1ZrBRL-0005Vm-Po; Tue, 27 Oct 2015 21:05:55 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1ZrBQm-0005Ao-BD for kernel-team@lists.ubuntu.com; Tue, 27 Oct 2015 21:05:20 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1ZrBQk-0005a1-Jz; Tue, 27 Oct 2015 21:05:19 +0000 Received: from kamal by fourier with local (Exim 4.82) (envelope-from ) id 1ZrBQh-0007yF-PJ; Tue, 27 Oct 2015 14:05:15 -0700 From: Kamal Mostafa To: Paul Mackerras Subject: [3.13.y-ckt stable] Patch "powerpc/MSI: Fix race condition in tearing down MSI interrupts" has been added to staging queue Date: Tue, 27 Oct 2015 14:05:15 -0700 Message-Id: <1445979915-30588-1-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 X-Extended-Stable: 3.13 Cc: Alexey Kardashevskiy , Kamal Mostafa , Paul Mackerras , kernel-team@lists.ubuntu.com X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled powerpc/MSI: Fix race condition in tearing down MSI interrupts to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt29. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From e6d78946d6ca8cf144e2c2c7c711e462ebfc4d2d Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Thu, 10 Sep 2015 14:36:21 +1000 Subject: powerpc/MSI: Fix race condition in tearing down MSI interrupts commit e297c939b745e420ef0b9dc989cb87bda617b399 upstream. This fixes a race which can result in the same virtual IRQ number being assigned to two different MSI interrupts. The most visible consequence of that is usually a warning and stack trace from the sysfs code about an attempt to create a duplicate entry in sysfs. The race happens when one CPU (say CPU 0) is disposing of an MSI while another CPU (say CPU 1) is setting up an MSI. CPU 0 calls (for example) pnv_teardown_msi_irqs(), which calls msi_bitmap_free_hwirqs() to indicate that the MSI (i.e. its hardware IRQ number) is no longer in use. Then, before CPU 0 gets to calling irq_dispose_mapping() to free up the virtal IRQ number, CPU 1 comes in and calls msi_bitmap_alloc_hwirqs() to allocate an MSI, and gets the same hardware IRQ number that CPU 0 just freed. CPU 1 then calls irq_create_mapping() to get a virtual IRQ number, which sees that there is currently a mapping for that hardware IRQ number and returns the corresponding virtual IRQ number (which is the same virtual IRQ number that CPU 0 was using). CPU 0 then calls irq_dispose_mapping() and frees that virtual IRQ number. Now, if another CPU comes along and calls irq_create_mapping(), it is likely to get the virtual IRQ number that was just freed, resulting in the same virtual IRQ number apparently being used for two different hardware interrupts. To fix this race, we just move the call to msi_bitmap_free_hwirqs() to after the call to irq_dispose_mapping(). Since virq_to_hw() doesn't work for the virtual IRQ number after irq_dispose_mapping() has been called, we need to call it before irq_dispose_mapping() and remember the result for the msi_bitmap_free_hwirqs() call. The pattern of calling msi_bitmap_free_hwirqs() before irq_dispose_mapping() appears in 5 places under arch/powerpc, and appears to have originated in commit 05af7bd2d75e ("[POWERPC] MPIC U3/U4 MSI backend") from 2007. Fixes: 05af7bd2d75e ("[POWERPC] MPIC U3/U4 MSI backend") Reported-by: Alexey Kardashevskiy Signed-off-by: Paul Mackerras Signed-off-by: Michael Ellerman [ kamal: backport to 3.19-stable: pasemi/msi.c --> arch/powerpc/sysdev/mpic_pasemi_msi.c ] Signed-off-by: Kamal Mostafa --- arch/powerpc/platforms/powernv/pci.c | 5 +++-- arch/powerpc/sysdev/fsl_msi.c | 5 +++-- arch/powerpc/sysdev/mpic_pasemi_msi.c | 5 +++-- arch/powerpc/sysdev/mpic_u3msi.c | 5 +++-- arch/powerpc/sysdev/ppc4xx_msi.c | 5 +++-- 5 files changed, 15 insertions(+), 10 deletions(-) -- 1.9.1 diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c index 5bd801b..2f32872 100644 --- a/arch/powerpc/platforms/powernv/pci.c +++ b/arch/powerpc/platforms/powernv/pci.c @@ -108,6 +108,7 @@ static void pnv_teardown_msi_irqs(struct pci_dev *pdev) struct pci_controller *hose = pci_bus_to_host(pdev->bus); struct pnv_phb *phb = hose->private_data; struct msi_desc *entry; + irq_hw_number_t hwirq; if (WARN_ON(!phb)) return; @@ -115,10 +116,10 @@ static void pnv_teardown_msi_irqs(struct pci_dev *pdev) list_for_each_entry(entry, &pdev->msi_list, list) { if (entry->irq == NO_IRQ) continue; + hwirq = virq_to_hw(entry->irq); irq_set_msi_desc(entry->irq, NULL); - msi_bitmap_free_hwirqs(&phb->msi_bmp, - virq_to_hw(entry->irq) - phb->msi_base, 1); irq_dispose_mapping(entry->irq); + msi_bitmap_free_hwirqs(&phb->msi_bmp, hwirq - phb->msi_base, 1); } } #endif /* CONFIG_PCI_MSI */ diff --git a/arch/powerpc/sysdev/fsl_msi.c b/arch/powerpc/sysdev/fsl_msi.c index 77efbae..4a9b367 100644 --- a/arch/powerpc/sysdev/fsl_msi.c +++ b/arch/powerpc/sysdev/fsl_msi.c @@ -121,15 +121,16 @@ static void fsl_teardown_msi_irqs(struct pci_dev *pdev) { struct msi_desc *entry; struct fsl_msi *msi_data; + irq_hw_number_t hwirq; list_for_each_entry(entry, &pdev->msi_list, list) { if (entry->irq == NO_IRQ) continue; + hwirq = virq_to_hw(entry->irq); msi_data = irq_get_chip_data(entry->irq); irq_set_msi_desc(entry->irq, NULL); - msi_bitmap_free_hwirqs(&msi_data->bitmap, - virq_to_hw(entry->irq), 1); irq_dispose_mapping(entry->irq); + msi_bitmap_free_hwirqs(&msi_data->bitmap, hwirq, 1); } return; diff --git a/arch/powerpc/sysdev/mpic_pasemi_msi.c b/arch/powerpc/sysdev/mpic_pasemi_msi.c index 38e6238..e873616 100644 --- a/arch/powerpc/sysdev/mpic_pasemi_msi.c +++ b/arch/powerpc/sysdev/mpic_pasemi_msi.c @@ -74,6 +74,7 @@ static int pasemi_msi_check_device(struct pci_dev *pdev, int nvec, int type) static void pasemi_msi_teardown_msi_irqs(struct pci_dev *pdev) { struct msi_desc *entry; + irq_hw_number_t hwirq; pr_debug("pasemi_msi_teardown_msi_irqs, pdev %p\n", pdev); @@ -81,10 +82,10 @@ static void pasemi_msi_teardown_msi_irqs(struct pci_dev *pdev) if (entry->irq == NO_IRQ) continue; + hwirq = virq_to_hw(entry->irq); irq_set_msi_desc(entry->irq, NULL); - msi_bitmap_free_hwirqs(&msi_mpic->msi_bitmap, - virq_to_hw(entry->irq), ALLOC_CHUNK); irq_dispose_mapping(entry->irq); + msi_bitmap_free_hwirqs(&msi_mpic->msi_bitmap, hwirq, ALLOC_CHUNK); } return; diff --git a/arch/powerpc/sysdev/mpic_u3msi.c b/arch/powerpc/sysdev/mpic_u3msi.c index 9a7aa0e..dfc3486 100644 --- a/arch/powerpc/sysdev/mpic_u3msi.c +++ b/arch/powerpc/sysdev/mpic_u3msi.c @@ -124,15 +124,16 @@ static int u3msi_msi_check_device(struct pci_dev *pdev, int nvec, int type) static void u3msi_teardown_msi_irqs(struct pci_dev *pdev) { struct msi_desc *entry; + irq_hw_number_t hwirq; list_for_each_entry(entry, &pdev->msi_list, list) { if (entry->irq == NO_IRQ) continue; + hwirq = virq_to_hw(entry->irq); irq_set_msi_desc(entry->irq, NULL); - msi_bitmap_free_hwirqs(&msi_mpic->msi_bitmap, - virq_to_hw(entry->irq), 1); irq_dispose_mapping(entry->irq); + msi_bitmap_free_hwirqs(&msi_mpic->msi_bitmap, hwirq, 1); } return; diff --git a/arch/powerpc/sysdev/ppc4xx_msi.c b/arch/powerpc/sysdev/ppc4xx_msi.c index 43948da..c3e6512 100644 --- a/arch/powerpc/sysdev/ppc4xx_msi.c +++ b/arch/powerpc/sysdev/ppc4xx_msi.c @@ -121,16 +121,17 @@ void ppc4xx_teardown_msi_irqs(struct pci_dev *dev) { struct msi_desc *entry; struct ppc4xx_msi *msi_data = &ppc4xx_msi; + irq_hw_number_t hwirq; dev_dbg(&dev->dev, "PCIE-MSI: tearing down msi irqs\n"); list_for_each_entry(entry, &dev->msi_list, list) { if (entry->irq == NO_IRQ) continue; + hwirq = virq_to_hw(entry->irq); irq_set_msi_desc(entry->irq, NULL); - msi_bitmap_free_hwirqs(&msi_data->bitmap, - virq_to_hw(entry->irq), 1); irq_dispose_mapping(entry->irq); + msi_bitmap_free_hwirqs(&msi_data->bitmap, hwirq, 1); } }