Commit 9474933caf21 ("igb: close/suspend race in netif_device_detach")
fixed race condition between close and power management ops by using
rtnl_lock().
However we can achieve the same by using device_lock() since all power
management ops are protected by device_lock().
This fix is a preparation for next patch, to prevent a dead lock under
rtnl_lock() when calling runtime resume routine.
Signed-off-by: Kai-Heng Feng <[email protected]>
---
v2:
- No change.
drivers/net/ethernet/intel/igb/igb_main.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index b46bff8fe056..3750e2b926b1 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -4026,8 +4026,13 @@ static int __igb_close(struct net_device *netdev, bool suspending)
int igb_close(struct net_device *netdev)
{
+ struct igb_adapter *adapter = netdev_priv(netdev);
+ struct device *dev = &adapter->pdev->dev;
+
+ device_lock(dev);
if (netif_device_present(netdev) || netdev->dismantle)
return __igb_close(netdev, false);
+ device_unlock(dev);
return 0;
}
@@ -8760,7 +8765,6 @@ static int __igb_shutdown(struct pci_dev *pdev, bool *enable_wake,
u32 wufc = runtime ? E1000_WUFC_LNKC : adapter->wol;
bool wake;
- rtnl_lock();
netif_device_detach(netdev);
if (netif_running(netdev))
@@ -8769,7 +8773,6 @@ static int __igb_shutdown(struct pci_dev *pdev, bool *enable_wake,
igb_ptp_suspend(adapter);
igb_clear_interrupt_scheme(adapter);
- rtnl_unlock();
status = rd32(E1000_STATUS);
if (status & E1000_STATUS_LU)
@@ -8897,13 +8900,11 @@ static int __maybe_unused igb_resume(struct device *dev)
wr32(E1000_WUS, ~0);
- rtnl_lock();
if (!err && netif_running(netdev))
err = __igb_open(netdev, true);
if (!err)
netif_device_attach(netdev);
- rtnl_unlock();
return err;
}
--
2.17.1
Device like igb gets runtime suspended when there's no link partner. We
can't get correct speed under that state:
$ cat /sys/class/net/enp3s0/speed
1000
In addition to that, an error can also be spotted in dmesg:
[ 385.991957] igb 0000:03:00.0 enp3s0: PCIe link lost
It's because the igb device doesn't get runtime resumed before calling
get_link_ksettings().
So let's use a new helper to call begin() and complete() like what
dev_ethtool() does, to runtime resume/suspend or power up/down the
device properly.
Once this fix is in place, igb can show the speed correctly without link
partner:
$ cat /sys/class/net/enp3s0/speed
-1
Signed-off-by: Kai-Heng Feng <[email protected]>
---
v2:
- Add a new helper with begin/complete and use it in net-sysfs.
include/linux/ethtool.h | 4 ++++
net/core/net-sysfs.c | 4 ++--
net/ethtool/ioctl.c | 33 ++++++++++++++++++++++++++++++++-
3 files changed, 38 insertions(+), 3 deletions(-)
diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 95991e4300bf..785ec1921417 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -160,6 +160,10 @@ extern int
__ethtool_get_link_ksettings(struct net_device *dev,
struct ethtool_link_ksettings *link_ksettings);
+extern int
+__ethtool_get_link_ksettings_full(struct net_device *dev,
+ struct ethtool_link_ksettings *link_ksettings);
+
/**
* ethtool_intersect_link_masks - Given two link masks, AND them together
* @dst: first mask and where result is stored
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 4c826b8bf9b1..a199e15a080f 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -201,7 +201,7 @@ static ssize_t speed_show(struct device *dev,
if (netif_running(netdev)) {
struct ethtool_link_ksettings cmd;
- if (!__ethtool_get_link_ksettings(netdev, &cmd))
+ if (!__ethtool_get_link_ksettings_full(netdev, &cmd))
ret = sprintf(buf, fmt_dec, cmd.base.speed);
}
rtnl_unlock();
@@ -221,7 +221,7 @@ static ssize_t duplex_show(struct device *dev,
if (netif_running(netdev)) {
struct ethtool_link_ksettings cmd;
- if (!__ethtool_get_link_ksettings(netdev, &cmd)) {
+ if (!__ethtool_get_link_ksettings_full(netdev, &cmd)) {
const char *duplex;
switch (cmd.base.duplex) {
diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index b987052d91ef..faeba247c1fb 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -420,7 +420,9 @@ struct ethtool_link_usettings {
} link_modes;
};
-/* Internal kernel helper to query a device ethtool_link_settings. */
+/* Internal kernel helper to query a device ethtool_link_settings. To be called
+ * inside begin/complete block.
+ */
int __ethtool_get_link_ksettings(struct net_device *dev,
struct ethtool_link_ksettings *link_ksettings)
{
@@ -434,6 +436,35 @@ int __ethtool_get_link_ksettings(struct net_device *dev,
}
EXPORT_SYMBOL(__ethtool_get_link_ksettings);
+/* Internal kernel helper to query a device ethtool_link_settings. To be called
+ * outside of begin/complete block.
+ */
+int __ethtool_get_link_ksettings_full(struct net_device *dev,
+ struct ethtool_link_ksettings *link_ksettings)
+{
+ int rc;
+
+ ASSERT_RTNL();
+
+ if (!dev->ethtool_ops->get_link_ksettings)
+ return -EOPNOTSUPP;
+
+ if (dev->ethtool_ops->begin) {
+ rc = dev->ethtool_ops->begin(dev);
+ if (rc < 0)
+ return rc;
+ }
+
+ memset(link_ksettings, 0, sizeof(*link_ksettings));
+ rc = dev->ethtool_ops->get_link_ksettings(dev, link_ksettings);
+
+ if (dev->ethtool_ops->complete)
+ dev->ethtool_ops->complete(dev);
+
+ return rc;
+}
+EXPORT_SYMBOL(__ethtool_get_link_ksettings_full);
+
/* convert ethtool_link_usettings in user space to a kernel internal
* ethtool_link_ksettings. return 0 on success, errno on error.
*/
--
2.17.1
On Wed, Feb 05, 2020 at 04:16:16PM +0800, Kai-Heng Feng wrote:
> Device like igb gets runtime suspended when there's no link partner. We
> can't get correct speed under that state:
> $ cat /sys/class/net/enp3s0/speed
> 1000
>
> In addition to that, an error can also be spotted in dmesg:
> [ 385.991957] igb 0000:03:00.0 enp3s0: PCIe link lost
>
> It's because the igb device doesn't get runtime resumed before calling
> get_link_ksettings().
>
> So let's use a new helper to call begin() and complete() like what
> dev_ethtool() does, to runtime resume/suspend or power up/down the
> device properly.
>
> Once this fix is in place, igb can show the speed correctly without link
> partner:
> $ cat /sys/class/net/enp3s0/speed
> -1
What is the meaning of -1? Does it tells us "Hey, something is bad in hardware
I can't tell you the speed" or does it imply anything else?
Wouldn't be better to report 0?
Where is the documentation part of this ABI change?
--
With Best Regards,
Andy Shevchenko
On Wed, 5 Feb 2020 11:06:38 +0200
Andy Shevchenko <[email protected]> wrote:
> On Wed, Feb 05, 2020 at 04:16:16PM +0800, Kai-Heng Feng wrote:
> > Device like igb gets runtime suspended when there's no link partner. We
> > can't get correct speed under that state:
> > $ cat /sys/class/net/enp3s0/speed
> > 1000
> >
> > In addition to that, an error can also be spotted in dmesg:
> > [ 385.991957] igb 0000:03:00.0 enp3s0: PCIe link lost
> >
> > It's because the igb device doesn't get runtime resumed before calling
> > get_link_ksettings().
> >
> > So let's use a new helper to call begin() and complete() like what
> > dev_ethtool() does, to runtime resume/suspend or power up/down the
> > device properly.
> >
> > Once this fix is in place, igb can show the speed correctly without link
> > partner:
> > $ cat /sys/class/net/enp3s0/speed
> > -1
>
> What is the meaning of -1? Does it tells us "Hey, something is bad in hardware
> I can't tell you the speed" or does it imply anything else?
>
> Wouldn't be better to report 0?
>
> Where is the documentation part of this ABI change?
>
The speed value of -1 is defined in ethtool.h as:
#define SPEED_UNKNOWN -1
On Wed, Feb 05, 2020 at 11:06:38AM +0200, Andy Shevchenko wrote:
> On Wed, Feb 05, 2020 at 04:16:16PM +0800, Kai-Heng Feng wrote:
> > Device like igb gets runtime suspended when there's no link partner. We
> > can't get correct speed under that state:
> > $ cat /sys/class/net/enp3s0/speed
> > 1000
> >
> > In addition to that, an error can also be spotted in dmesg:
> > [ 385.991957] igb 0000:03:00.0 enp3s0: PCIe link lost
> >
> > It's because the igb device doesn't get runtime resumed before calling
> > get_link_ksettings().
> >
> > So let's use a new helper to call begin() and complete() like what
> > dev_ethtool() does, to runtime resume/suspend or power up/down the
> > device properly.
> >
> > Once this fix is in place, igb can show the speed correctly without link
> > partner:
> > $ cat /sys/class/net/enp3s0/speed
> > -1
>
> What is the meaning of -1? Does it tells us "Hey, something is bad in hardware
> I can't tell you the speed" or does it imply anything else?
It's SPEED_UNKNOWN constant printed with "%d" template.
> Wouldn't be better to report 0?
>
> Where is the documentation part of this ABI change?
It's not an ABI change, /sys/class/net/*/speed already shows -1 when the
device reports SPEED_UNKNOWN. The only change is that after this patch,
igb driver reports SPEED_UNKNOWN rather than an outdated value if there
is no link.
Michal
On Wed, Feb 05, 2020 at 10:23:45AM +0100, Michal Kubecek wrote:
> On Wed, Feb 05, 2020 at 11:06:38AM +0200, Andy Shevchenko wrote:
> > On Wed, Feb 05, 2020 at 04:16:16PM +0800, Kai-Heng Feng wrote:
> > > Device like igb gets runtime suspended when there's no link partner. We
> > > can't get correct speed under that state:
> > > $ cat /sys/class/net/enp3s0/speed
> > > 1000
> > >
> > > In addition to that, an error can also be spotted in dmesg:
> > > [ 385.991957] igb 0000:03:00.0 enp3s0: PCIe link lost
> > >
> > > It's because the igb device doesn't get runtime resumed before calling
> > > get_link_ksettings().
> > >
> > > So let's use a new helper to call begin() and complete() like what
> > > dev_ethtool() does, to runtime resume/suspend or power up/down the
> > > device properly.
> > >
> > > Once this fix is in place, igb can show the speed correctly without link
> > > partner:
> > > $ cat /sys/class/net/enp3s0/speed
> > > -1
> >
> > What is the meaning of -1? Does it tells us "Hey, something is bad in hardware
> > I can't tell you the speed" or does it imply anything else?
>
> It's SPEED_UNKNOWN constant printed with "%d" template.
>
> > Wouldn't be better to report 0?
> >
> > Where is the documentation part of this ABI change?
>
> It's not an ABI change, /sys/class/net/*/speed already shows -1 when the
> device reports SPEED_UNKNOWN. The only change is that after this patch,
> igb driver reports SPEED_UNKNOWN rather than an outdated value if there
> is no link.
Thanks for elaboration.
Perhaps add a couple of words to the commit message that there is no ABI
changes.
--
With Best Regards,
Andy Shevchenko
Hi Kai-Heng,
url: https://github.com/0day-ci/linux/commits/Kai-Heng-Feng/igb-Use-device_lock-insead-of-rtnl_lock/20200205-174208
base: https://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/next-queue.git dev-queue
If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <[email protected]>
Reported-by: Dan Carpenter <[email protected]>
New smatch warnings:
drivers/net/ethernet/intel/igb/igb_main.c:4036 igb_close() warn: inconsistent returns 'dev->mutex'.
# https://github.com/0day-ci/linux/commit/905877ae7d44efc1d9c5c1ae9f4489f56bcb13a6
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 905877ae7d44efc1d9c5c1ae9f4489f56bcb13a6
vim +4036 drivers/net/ethernet/intel/igb/igb_main.c
9d5c824399dea8 drivers/net/igb/igb_main.c Auke Kok 2008-01-24 4026
46eafa59e18d03 drivers/net/ethernet/intel/igb/igb_main.c Stefan Assmann 2016-02-03 4027 int igb_close(struct net_device *netdev)
749ab2cd127046 drivers/net/ethernet/intel/igb/igb_main.c Yan, Zheng 2012-01-04 4028 {
905877ae7d44ef drivers/net/ethernet/intel/igb/igb_main.c Kai-Heng Feng 2020-02-05 4029 struct igb_adapter *adapter = netdev_priv(netdev);
905877ae7d44ef drivers/net/ethernet/intel/igb/igb_main.c Kai-Heng Feng 2020-02-05 4030 struct device *dev = &adapter->pdev->dev;
905877ae7d44ef drivers/net/ethernet/intel/igb/igb_main.c Kai-Heng Feng 2020-02-05 4031
905877ae7d44ef drivers/net/ethernet/intel/igb/igb_main.c Kai-Heng Feng 2020-02-05 4032 device_lock(dev);
888f22931478a0 drivers/net/ethernet/intel/igb/igb_main.c Lyude Paul 2017-12-12 4033 if (netif_device_present(netdev) || netdev->dismantle)
749ab2cd127046 drivers/net/ethernet/intel/igb/igb_main.c Yan, Zheng 2012-01-04 4034 return __igb_close(netdev, false);
^^^^^^
Lock held for this return.
905877ae7d44ef drivers/net/ethernet/intel/igb/igb_main.c Kai-Heng Feng 2020-02-05 4035 device_unlock(dev);
9474933caf21a4 drivers/net/ethernet/intel/igb/igb_main.c Todd Fujinaka 2016-11-15 @4036 return 0;
749ab2cd127046 drivers/net/ethernet/intel/igb/igb_main.c Yan, Zheng 2012-01-04 4037 }
749ab2cd127046 drivers/net/ethernet/intel/igb/igb_main.c Yan, Zheng 2012-01-04 4038
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/hyperkitty/list/[email protected] Intel Corporation