Re: [PATCH] pci: fix invalid list entry warning for double pci deviceremoving via sysfs

From: Yinghai Lu
Date: Thu Oct 31 2013 - 02:45:43 EST

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In reply to: Gu Zheng: "Re: [PATCH] pci: fix invalid list entry warning for double pci deviceremoving via sysfs"
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On Wed, Oct 30, 2013 at 3:14 AM, Gu Zheng <guz.fnst@xxxxxxxxxxxxxx> wrote:
> When concurent removing pci devices which are in the same pci subtree
> via sysfs, such as:
> echo -n 1 > /sys/bus/pci/devices/0000\:10\:00.0/remove ; echo -n 1 >
> /sys/bus/pci/devices/0000\:1a\:01.0/remove
> (1a:01.0 device is downstream from the 10:00.0 bridge)
>
> the following warning will show:
> [ 1799.280918] ------------[ cut here ]------------
> [ 1799.336199] WARNING: CPU: 7 PID: 126 at lib/list_debug.c:53 __list_del_entry+0x63/0xd0()
> [ 1799.433093] list_del corruption, ffff8807b4a7c000->next is LIST_POISON1 (dead000000100100)
> [ 1799.532110] Modules linked in: nf_conntrack_netbios_ns nf_conntrack_broadcast ipt_MASQUERADE ip6table_mangle ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 iptable_nat nf_nat_ipv4 nf_nat iptable_mangle ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter ip_tables sg dm_mirror dm_region_hash dm_log dm_mod vfat fat e1000e igb iTCO_wdt iTCO_vendor_support ioatdma ptp i7core_edac ipmi_si edac_core lpc_ich pps_core i2c_i801 pcspkr mfd_core dca ipmi_msghandler acpi_cpufreq xfs libcrc32c sd_mod crc_t10dif crct10dif_common i2c_algo_bit drm_kms_helper ttm drm mptsas scsi_transport_sas mptscsih i2c_core megaraid_sas mptbase
> [ 1800.276623] CPU: 7 PID: 126 Comm: kworker/u512:1 Tainted: G W 3.12.0-rc5+ #196
> [ 1800.508918] Workqueue: sysfsd sysfs_schedule_callback_work
> [ 1800.574703] 0000000000000009 ffff8807adbadbd8 ffffffff8168b26c ffff8807c27d08a8
> [ 1800.663860] ffff8807adbadc28 ffff8807adbadc18 ffffffff810711dc ffff8807adbadc68
> [ 1800.753130] ffff8807b4a7c000 ffff8807b4a7c000 ffff8807ad089c00 0000000000000000
> [ 1800.842282] Call Trace:
> [ 1800.871651] [<ffffffff8168b26c>] dump_stack+0x55/0x76
> [ 1800.933301] [<ffffffff810711dc>] warn_slowpath_common+0x8c/0xc0
> [ 1801.005283] [<ffffffff810712c6>] warn_slowpath_fmt+0x46/0x50
> [ 1801.074081] [<ffffffff8135a343>] __list_del_entry+0x63/0xd0
> [ 1801.141839] [<ffffffff8135a3c1>] list_del+0x11/0x40
> [ 1801.201320] [<ffffffff813734da>] pci_remove_bus_device+0x6a/0xe0
> [ 1801.274279] [<ffffffff8137356e>] pci_stop_and_remove_bus_device+0x1e/0x30
> [ 1801.356606] [<ffffffff8137b20b>] remove_callback+0x2b/0x40
> [ 1801.423412] [<ffffffff81251848>] sysfs_schedule_callback_work+0x18/0x60
> [ 1801.503744] [<ffffffff8108eab5>] process_one_work+0x1f5/0x540
> [ 1801.573640] [<ffffffff8108ea53>] ? process_one_work+0x193/0x540
> [ 1801.645616] [<ffffffff8108f2ac>] worker_thread+0x11c/0x370
> [ 1801.712337] [<ffffffff8108f190>] ? rescuer_thread+0x350/0x350
> [ 1801.782178] [<ffffffff8109731d>] kthread+0xed/0x100
> [ 1801.841661] [<ffffffff81097230>] ? kthread_create_on_node+0x160/0x160
> [ 1801.919919] [<ffffffff8169cc3c>] ret_from_fork+0x7c/0xb0
> [ 1801.984608] [<ffffffff81097230>] ? kthread_create_on_node+0x160/0x160
> [ 1802.062825] ---[ end trace d77f2054de000fb7 ]---
>
> This issue is related to the bug 54411:
> https://bugzilla.kernel.org/show_bug.cgi?id=54411
>
> Since we added the pci_bus reference management, the bug becomes a
> invalid list entry warning as descripted above. Beacuse it still
> trys to delete an deleted pci device from device list.
>
> So here we make stop device actually detach driver only, and remove
> device will do device_del instead, and move bus_list change and pci device
> resource free into pci_release_dev, so that it'll consistent with
> bus reference managment, and the device only can be deleted from device
> list in pci_release_dev just for one time.
>
> Besides, it also makes hostbridge to use device_unregister to be pair
> with device_register before.
>
> This patch is based on Yinghai's privious similar patch:
> http://lkml.org/lkml/2013/5/13/658

I have updated version, please check if attached patches fix the problem.

virtfn_release.patch
fix_cx3_hotplug_2.patch
fix_racing_removing_6_1.patch
fix_racing_removing_6_2.patch
fix_racing_removing_6_3.patch

Thanks

Yinghai
Subject: [PATCH] PCI: Release PF ref during removing VF
From: Yinghai Lu <yinghai@xxxxxxxxxx>

commit dc087f2f6a2925e81831f3016b9cbb6e470e7423
(PCI: Simplify IOV implementation and fix reference count races)
broke the pcie native hotplug with SRIOV enabled: PF is not freed
during hot-remove, and later hot-add do not work as old pci_dev
is still around, and can not create new pci_dev.

That commit need VFs to be removed via pci_disable_sriov/virtfn_remove
to make sure ref to PF is put back.

So we can not call stop_and_remove for VF before PF, that will
make VF get removed directly before PF's driver try to use
pci_disable_sriov/virtfn_remove to do it.

Solution would be
1. separating stop and remove in two iterations.
2. or make pci_stop_and_remove_bus_device could be used on VF.

This patch is second solution:
Separate PF ref releasing from virtfn_remove, all that during
pci_destroy_dev for VFs.

-v2: fix warning when SRIOV is not defined.

Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

---
drivers/pci/iov.c | 34 +++++++++++++++++++++++++++++-----
drivers/pci/pci.h | 4 ++++
drivers/pci/remove.c | 17 +++++++++++++++++
3 files changed, 50 insertions(+), 5 deletions(-)

Index: linux-2.6/drivers/pci/iov.c
===================================================================
--- linux-2.6.orig/drivers/pci/iov.c
+++ linux-2.6/drivers/pci/iov.c
@@ -132,9 +132,37 @@ failed:
return rc;
}

-static void virtfn_remove(struct pci_dev *dev, int id, int reset)
+void virtfn_release(struct pci_dev *virtfn)
{
+ int i;
+ struct pci_dev *dev;
char buf[VIRTFN_ID_LEN];
+
+ if (!virtfn->is_virtfn)
+ return;
+
+ dev = virtfn->physfn;
+
+ /*
+ * Remove link to virtfn for PF.
+ * pci_disable_sriov() could be called after pci_stop_dev() is
+ * called for PF. So check sd to avoid spurious sfsfs warning.
+ */
+ if (dev->dev.kobj.sd)
+ for (i = 0; i < dev->sriov->num_VFs; i++)
+ if ((virtfn_bus(dev, i) == virtfn->bus->number) &&
+ (virtfn_devfn(dev, i) == virtfn->devfn)) {
+ sprintf(buf, "virtfn%u", i);
+ sysfs_remove_link(&dev->dev.kobj, buf);
+ break;
+ }
+
+ virtfn_remove_bus(dev->bus, virtfn->bus);
+ pci_dev_put(dev);
+}
+
+static void virtfn_remove(struct pci_dev *dev, int id, int reset)
+{
struct pci_dev *virtfn;
struct pci_sriov *iov = dev->sriov;

@@ -149,8 +177,6 @@ static void virtfn_remove(struct pci_dev
__pci_reset_function(virtfn);
}

- sprintf(buf, "virtfn%u", id);
- sysfs_remove_link(&dev->dev.kobj, buf);
/*
* pci_stop_dev() could have been called for this virtfn already,
* so the directory for the virtfn may have been removed before.
@@ -161,12 +187,10 @@ static void virtfn_remove(struct pci_dev

mutex_lock(&iov->dev->sriov->lock);
pci_stop_and_remove_bus_device(virtfn);
- virtfn_remove_bus(dev->bus, virtfn->bus);
mutex_unlock(&iov->dev->sriov->lock);

/* balance pci_get_domain_bus_and_slot() */
pci_dev_put(virtfn);
- pci_dev_put(dev);
}

static int sriov_migration(struct pci_dev *dev)
Index: linux-2.6/drivers/pci/pci.h
===================================================================
--- linux-2.6.orig/drivers/pci/pci.h
+++ linux-2.6/drivers/pci/pci.h
@@ -259,6 +259,7 @@ int pci_iov_resource_bar(struct pci_dev
resource_size_t pci_sriov_resource_alignment(struct pci_dev *dev, int resno);
void pci_restore_iov_state(struct pci_dev *dev);
int pci_iov_bus_range(struct pci_bus *bus);
+void virtfn_release(struct pci_dev *dev);

#else
static inline int pci_iov_init(struct pci_dev *dev)
@@ -281,6 +282,9 @@ static inline int pci_iov_bus_range(stru
{
return 0;
}
+static inline void virtfn_release(struct pci_dev *dev)
+{
+}

#endif /* CONFIG_PCI_IOV */

Index: linux-2.6/drivers/pci/remove.c
===================================================================
--- linux-2.6.orig/drivers/pci/remove.c
+++ linux-2.6/drivers/pci/remove.c
@@ -38,6 +38,8 @@ static void pci_destroy_dev(struct pci_d
list_del(&dev->bus_list);
up_write(&pci_bus_sem);

+ virtfn_release(dev);
+
pci_free_resources(dev);
put_device(&dev->dev);
}
@@ -107,8 +109,23 @@ static void pci_remove_bus_device(struct
*/
void pci_stop_and_remove_bus_device(struct pci_dev *dev)
{
+#ifdef CONFIG_PCI_ATS
+ struct pci_sriov *iov = NULL;
+ int locked = 0;
+
+ if (dev->is_virtfn) {
+ iov = dev->physfn->sriov;
+ locked = mutex_trylock(&iov->dev->sriov->lock);
+ }
+#endif
+
pci_stop_bus_device(dev);
pci_remove_bus_device(dev);
+
+#ifdef CONFIG_PCI_ATS
+ if (locked)
+ mutex_unlock(&iov->dev->sriov->lock);
+#endif
}
EXPORT_SYMBOL(pci_stop_and_remove_bus_device);

Subject: [PATCH v2 3/3] PCI: Stop sriov after stop PF if PF's driver skip that
From: Yinghai Lu <yinghai@xxxxxxxxxx>

After commit dc087f2f6a2925e81831f3016b9cbb6e470e7423
(PCI: Simplify IOV implementation and fix reference count races)
VF need to be removed via virtfn_remove to make sure ref to PF
is put back.

Some driver (like ixgbe) does not call pci_disable_sriov() if
sriov is enabled via /sys/.../sriov_numvfs setting.
ixgbe does allow driver for PF get detached, but still have VFs
around.

But how about PF get removed via /sys or pciehp finally?

During hot-remove, VF will still hold one ref to PF and it
prevent PF to be removed.
That make the next hot-add fails, as old PF dev struct is still around.

We need to add pci_disable_sriov() calling during stop PF .

Need this one for v3.11

-v2: Accoring to Bjorn, move that calling to pci_stop_dev.

Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Jiang Liu <liuj97@xxxxxxxxx>
Cc: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
Cc: Donald Dutile <ddutile@xxxxxxxxxx>
Cc: Greg Rose <gregory.v.rose@xxxxxxxxx>

---
drivers/pci/remove.c | 2 ++
1 file changed, 2 insertions(+)

Index: linux-2.6/drivers/pci/remove.c
===================================================================
--- linux-2.6.orig/drivers/pci/remove.c
+++ linux-2.6/drivers/pci/remove.c
@@ -25,6 +25,8 @@ static void pci_stop_dev(struct pci_dev
pci_proc_detach_device(dev);
pci_remove_sysfs_dev_files(dev);
device_del(&dev->dev);
+ /* remove VF, if PF driver skip that */
+ pci_disable_sriov(dev);
dev->is_added = 0;
}

Subject: [PATCH 1/7] PCI: move back pci_proc_attach_devices calling
From: Yinghai Lu <yinghai@xxxxxxxxxx>

We stop detach proc when pci_stop_device.
So should attach that during pci_bus_add_device.

Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

---
drivers/pci/bus.c | 1 +
drivers/pci/probe.c | 2 --
2 files changed, 1 insertion(+), 2 deletions(-)

Index: linux-2.6/drivers/pci/probe.c
===================================================================
--- linux-2.6.orig/drivers/pci/probe.c
+++ linux-2.6/drivers/pci/probe.c
@@ -1382,8 +1382,6 @@ void pci_device_add(struct pci_dev *dev,
dev->match_driver = false;
ret = device_add(&dev->dev);
WARN_ON(ret < 0);
-
- pci_proc_attach_device(dev);
}

struct pci_dev *__ref pci_scan_single_device(struct pci_bus *bus, int devfn)
Index: linux-2.6/drivers/pci/bus.c
===================================================================
--- linux-2.6.orig/drivers/pci/bus.c
+++ linux-2.6/drivers/pci/bus.c
@@ -175,6 +175,7 @@ int pci_bus_add_device(struct pci_dev *d
* are not assigned yet for some devices.
*/
pci_fixup_device(pci_fixup_final, dev);
+ pci_proc_attach_device(dev);
pci_create_sysfs_dev_files(dev);

dev->match_driver = true;
Subject: [PATCH 2/7] PCI: move resources and bus_list releasing to pci_release_dev
From: Yinghai Lu <yinghai@xxxxxxxxxx>

We should not release resource in pci_destroy that is too early
as there could be still other use hold reference.

release them or remove it from bus devices list at last
in pci_release_dev instead.

Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

---
drivers/pci/probe.c | 25 +++++++++++++++++++++++--
drivers/pci/remove.c | 21 ---------------------
2 files changed, 23 insertions(+), 23 deletions(-)

Index: linux-2.6/drivers/pci/probe.c
===================================================================
--- linux-2.6.orig/drivers/pci/probe.c
+++ linux-2.6/drivers/pci/probe.c
@@ -1155,6 +1155,20 @@ static void pci_release_capabilities(str
pci_free_cap_save_buffers(dev);
}

+static void pci_free_resources(struct pci_dev *dev)
+{
+ int i;
+
+ msi_remove_pci_irq_vectors(dev);
+
+ pci_cleanup_rom(dev);
+ for (i = 0; i < PCI_NUM_RESOURCES; i++) {
+ struct resource *res = dev->resource + i;
+ if (res->parent)
+ release_resource(res);
+ }
+}
+
/**
* pci_release_dev - free a pci device structure when all users of it are finished.
* @dev: device that's been disconnected
@@ -1164,9 +1178,16 @@ static void pci_release_capabilities(str
*/
static void pci_release_dev(struct device *dev)
{
- struct pci_dev *pci_dev;
+ struct pci_dev *pci_dev = to_pci_dev(dev);
+
+ down_write(&pci_bus_sem);
+ list_del(&pci_dev->bus_list);
+ up_write(&pci_bus_sem);
+
+ virtfn_release(pci_dev);
+
+ pci_free_resources(pci_dev);

- pci_dev = to_pci_dev(dev);
pci_release_capabilities(pci_dev);
pci_release_of_node(pci_dev);
pcibios_release_device(pci_dev);
Index: linux-2.6/drivers/pci/remove.c
===================================================================
--- linux-2.6.orig/drivers/pci/remove.c
+++ linux-2.6/drivers/pci/remove.c
@@ -3,20 +3,6 @@
#include <linux/pci-aspm.h>
#include "pci.h"

-static void pci_free_resources(struct pci_dev *dev)
-{
- int i;
-
- msi_remove_pci_irq_vectors(dev);
-
- pci_cleanup_rom(dev);
- for (i = 0; i < PCI_NUM_RESOURCES; i++) {
- struct resource *res = dev->resource + i;
- if (res->parent)
- release_resource(res);
- }
-}
-
static void pci_stop_dev(struct pci_dev *dev)
{
pci_pme_active(dev, false);
@@ -36,13 +22,6 @@ static void pci_stop_dev(struct pci_dev

static void pci_destroy_dev(struct pci_dev *dev)
{
- down_write(&pci_bus_sem);
- list_del(&dev->bus_list);
- up_write(&pci_bus_sem);
-
- virtfn_release(dev);
-
- pci_free_resources(dev);
put_device(&dev->dev);
}

Subject: [PATCH 3/7] PCI: Destroy pci dev only once
From: Yinghai Lu <yinghai@xxxxxxxxxx>

Mutliple removing via /sys will call pci_destroy_dev two times.

Add is_removed to record if pci_destroy_dev is called already.

During second calling, still have extra dev ref hold via
device_schedule_call, so we are safe to check dev->is_removed.

Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

---
drivers/pci/remove.c | 5 ++++-
include/linux/pci.h | 1 +
2 files changed, 5 insertions(+), 1 deletion(-)

Index: linux-2.6/drivers/pci/remove.c
===================================================================
--- linux-2.6.orig/drivers/pci/remove.c
+++ linux-2.6/drivers/pci/remove.c
@@ -22,7 +22,10 @@ static void pci_stop_dev(struct pci_dev

static void pci_destroy_dev(struct pci_dev *dev)
{
- put_device(&dev->dev);
+ if (!dev->is_removed) {
+ dev->is_removed = 1;
+ put_device(&dev->dev);
+ }
}

void pci_remove_bus(struct pci_bus *bus)
Index: linux-2.6/include/linux/pci.h
===================================================================
--- linux-2.6.orig/include/linux/pci.h
+++ linux-2.6/include/linux/pci.h
@@ -308,6 +308,7 @@ struct pci_dev {
unsigned int multifunction:1;/* Part of multi-function device */
/* keep track of device state */
unsigned int is_added:1;
+ unsigned int is_removed:1; /* pci_destroy_dev is called */
unsigned int is_busmaster:1; /* device is busmaster */
unsigned int no_msi:1; /* device may not use msi */
unsigned int block_cfg_access:1; /* config space access is blocked */

Next message: Gleb Natapov: "Re: [PATCH RFC] kvm: optimize out smp_mb using srcu_read_unlock"
Previous message: Dave Airlie: "[drm pull] drm radeon fixes"
In reply to: Gu Zheng: "Re: [PATCH] pci: fix invalid list entry warning for double pci deviceremoving via sysfs"
Next in thread: Gu Zheng: "Re: [PATCH] pci: fix invalid list entry warning for double pci deviceremoving via sysfs"
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