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authorHari Vyas <hari.vyas@broadcom.com>2018-07-03 14:35:41 +0530
committerBjorn Helgaas <bhelgaas@google.com>2018-07-31 11:27:54 -0500
commit44bda4b7d26e9fffed6d7152d98a2e9edaeb2a76 (patch)
tree46ed284871234e825bc3211dd5bf0d960b7c3cda /arch/powerpc
parenta54e43f993f8ec2f063b616a0e4d2b09e08d78a5 (diff)
downloadlinux-44bda4b7d26e9fffed6d7152d98a2e9edaeb2a76.tar.bz2
PCI: Fix is_added/is_busmaster race condition
When a PCI device is detected, pdev->is_added is set to 1 and proc and sysfs entries are created. When the device is removed, pdev->is_added is checked for one and then device is detached with clearing of proc and sys entries and at end, pdev->is_added is set to 0. is_added and is_busmaster are bit fields in pci_dev structure sharing same memory location. A strange issue was observed with multiple removal and rescan of a PCIe NVMe device using sysfs commands where is_added flag was observed as zero instead of one while removing device and proc,sys entries are not cleared. This causes issue in later device addition with warning message "proc_dir_entry" already registered. Debugging revealed a race condition between the PCI core setting the is_added bit in pci_bus_add_device() and the NVMe driver reset work-queue setting the is_busmaster bit in pci_set_master(). As these fields are not handled atomically, that clears the is_added bit. Move the is_added bit to a separate private flag variable and use atomic functions to set and retrieve the device addition state. This avoids the race because is_added no longer shares a memory location with is_busmaster. Link: https://bugzilla.kernel.org/show_bug.cgi?id=200283 Signed-off-by: Hari Vyas <hari.vyas@broadcom.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Lukas Wunner <lukas@wunner.de> Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/kernel/pci-common.c4
-rw-r--r--arch/powerpc/platforms/powernv/pci-ioda.c3
-rw-r--r--arch/powerpc/platforms/pseries/setup.c3
3 files changed, 7 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index fe9733ffffaa..471aac313b89 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -42,6 +42,8 @@
#include <asm/ppc-pci.h>
#include <asm/eeh.h>
+#include "../../../drivers/pci/pci.h"
+
/* hose_spinlock protects accesses to the the phb_bitmap. */
static DEFINE_SPINLOCK(hose_spinlock);
LIST_HEAD(hose_list);
@@ -1014,7 +1016,7 @@ void pcibios_setup_bus_devices(struct pci_bus *bus)
/* Cardbus can call us to add new devices to a bus, so ignore
* those who are already fully discovered
*/
- if (dev->is_added)
+ if (pci_dev_is_added(dev))
continue;
pcibios_setup_device(dev);
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 5bd0eb6681bc..70b2e1e0f23c 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -46,6 +46,7 @@
#include "powernv.h"
#include "pci.h"
+#include "../../../../drivers/pci/pci.h"
#define PNV_IODA1_M64_NUM 16 /* Number of M64 BARs */
#define PNV_IODA1_M64_SEGS 8 /* Segments per M64 BAR */
@@ -3138,7 +3139,7 @@ static void pnv_pci_ioda_fixup_iov_resources(struct pci_dev *pdev)
struct pci_dn *pdn;
int mul, total_vfs;
- if (!pdev->is_physfn || pdev->is_added)
+ if (!pdev->is_physfn || pci_dev_is_added(pdev))
return;
pdn = pci_get_pdn(pdev);
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 139f0af6c3d9..8a4868a3964b 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -71,6 +71,7 @@
#include <asm/security_features.h>
#include "pseries.h"
+#include "../../../../drivers/pci/pci.h"
int CMO_PrPSP = -1;
int CMO_SecPSP = -1;
@@ -664,7 +665,7 @@ static void pseries_pci_fixup_iov_resources(struct pci_dev *pdev)
const int *indexes;
struct device_node *dn = pci_device_to_OF_node(pdev);
- if (!pdev->is_physfn || pdev->is_added)
+ if (!pdev->is_physfn || pci_dev_is_added(pdev))
return;
/*Firmware must support open sriov otherwise dont configure*/
indexes = of_get_property(dn, "ibm,open-sriov-vf-bar-info", NULL);