| Message ID | 20230403075657.168294-1-schnelle@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | net/mlx5: stop waiting for PCI link if reset is required | expand |
On Mon, Apr 03, 2023 at 09:56:56AM +0200, Niklas Schnelle wrote: > after an error on the PCI link, the driver does not need to wait > for the link to become functional again as a reset is required. Stop > the wait loop in this case to accelerate the recovery flow. > > Co-developed-by: Alexander Schmidt <alexs@linux.ibm.com> > Signed-off-by: Alexander Schmidt <alexs@linux.ibm.com> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > --- > drivers/net/ethernet/mellanox/mlx5/core/health.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/health.c b/drivers/net/ethernet/mellanox/mlx5/core/health.c > index f9438d4e43ca..81ca44e0705a 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/health.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/health.c > @@ -325,6 +325,8 @@ int mlx5_health_wait_pci_up(struct mlx5_core_dev *dev) > while (sensor_pci_not_working(dev)) { According to the comment in sensor_pci_not_working(), this loop is supposed to wait till PCI will be ready again. Otherwise, already in first iteration, we will bail out with pci_channel_offline() error. Thanks > if (time_after(jiffies, end)) > return -ETIMEDOUT; > + if (pci_channel_offline(dev->pdev)) > + return -EIO; > msleep(100); > } > return 0; > @@ -332,10 +334,16 @@ int mlx5_health_wait_pci_up(struct mlx5_core_dev *dev) > > static int mlx5_health_try_recover(struct mlx5_core_dev *dev) > { > + int rc; > + > mlx5_core_warn(dev, "handling bad device here\n"); > mlx5_handle_bad_state(dev); > - if (mlx5_health_wait_pci_up(dev)) { > - mlx5_core_err(dev, "health recovery flow aborted, PCI reads still not working\n"); > + rc = mlx5_health_wait_pci_up(dev); > + if (rc) { > + if (rc == -ETIMEDOUT) > + mlx5_core_err(dev, "health recovery flow aborted, PCI reads still not working\n"); > + else > + mlx5_core_err(dev, "health recovery flow aborted, PCI channel offline\n"); > return -EIO; > } > mlx5_core_err(dev, "starting health recovery flow\n"); > > base-commit: 7e364e56293bb98cae1b55fd835f5991c4e96e7d > -- > 2.37.2 >
On Mon, 2023-04-03 at 21:21 +0300, Leon Romanovsky wrote: > On Mon, Apr 03, 2023 at 09:56:56AM +0200, Niklas Schnelle wrote: > > after an error on the PCI link, the driver does not need to wait > > for the link to become functional again as a reset is required. Stop > > the wait loop in this case to accelerate the recovery flow. > > > > Co-developed-by: Alexander Schmidt <alexs@linux.ibm.com> > > Signed-off-by: Alexander Schmidt <alexs@linux.ibm.com> > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > > --- > > drivers/net/ethernet/mellanox/mlx5/core/health.c | 12 ++++++++++-- > > 1 file changed, 10 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/health.c b/drivers/net/ethernet/mellanox/mlx5/core/health.c > > index f9438d4e43ca..81ca44e0705a 100644 > > --- a/drivers/net/ethernet/mellanox/mlx5/core/health.c > > +++ b/drivers/net/ethernet/mellanox/mlx5/core/health.c > > @@ -325,6 +325,8 @@ int mlx5_health_wait_pci_up(struct mlx5_core_dev *dev) > > while (sensor_pci_not_working(dev)) { > > According to the comment in sensor_pci_not_working(), this loop is > supposed to wait till PCI will be ready again. Otherwise, already in > first iteration, we will bail out with pci_channel_offline() error. > > Thanks Well yes. The problem is that this works for intermittent errors including when the card resets itself which seems to be the use case in mlx5_fw_reset_complete_reload() and mlx5_devlink_reload_fw_activate(). If there is a PCI error that requires a link reset though we see some problems though it does work after running into the timeout. As I understand it and as implemented at least on s390, pci_channel_io_frozen is only set for fatal errors that require a reset while non fatal errors will have pci_channel_io_normal (see also Documentation/PCI/pcieaer-howto.rst) thus I think pci_channel_offline() should only be true if a reset is required or there is a permanent error. Furthermore in the pci_channel_io_frozen state the PCI function may be isolated and the reads will not reach the endpoint, this is the case at least on s390. Thus for errors requiring a reset the loop without pci_channel_offline() will run until the reset is performed or the timeout is reached. In the mlx5_health_try_recover() case during error recovery we will then indeed always loop until timeout, because the loop blocks mlx5_pci_err_detected() from returning thus blocking the reset (see Documentation/PCI/pci-error-recovery.rst). Adding Bjorn, maybe he can confirm or correct my assumptions here. Thanks, Niklas > > > if (time_after(jiffies, end)) > > return -ETIMEDOUT; > > + if (pci_channel_offline(dev->pdev)) > > + return -EIO; > > msleep(100); > > } > > return 0; > > @@ -332,10 +334,16 @@ int mlx5_health_wait_pci_up(struct mlx5_core_dev *dev) > > > > static int mlx5_health_try_recover(struct mlx5_core_dev *dev) > > { > > + int rc; > > + > > mlx5_core_warn(dev, "handling bad device here\n"); > > mlx5_handle_bad_state(dev); > > - if (mlx5_health_wait_pci_up(dev)) { > > - mlx5_core_err(dev, "health recovery flow aborted, PCI reads still not working\n"); > > + rc = mlx5_health_wait_pci_up(dev); > > + if (rc) { > > + if (rc == -ETIMEDOUT) > > + mlx5_core_err(dev, "health recovery flow aborted, PCI reads still not working\n"); > > + else > > + mlx5_core_err(dev, "health recovery flow aborted, PCI channel offline\n"); > > return -EIO; > > } > > mlx5_core_err(dev, "starting health recovery flow\n"); > > > > base-commit: 7e364e56293bb98cae1b55fd835f5991c4e96e7d > > -- > > 2.37.2 > >
On Tue, Apr 04, 2023 at 05:27:35PM +0200, Niklas Schnelle wrote: > On Mon, 2023-04-03 at 21:21 +0300, Leon Romanovsky wrote: > > On Mon, Apr 03, 2023 at 09:56:56AM +0200, Niklas Schnelle wrote: > > > after an error on the PCI link, the driver does not need to wait > > > for the link to become functional again as a reset is required. Stop > > > the wait loop in this case to accelerate the recovery flow. > > > > > > Co-developed-by: Alexander Schmidt <alexs@linux.ibm.com> > > > Signed-off-by: Alexander Schmidt <alexs@linux.ibm.com> > > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > > > --- > > > drivers/net/ethernet/mellanox/mlx5/core/health.c | 12 ++++++++++-- > > > 1 file changed, 10 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/health.c b/drivers/net/ethernet/mellanox/mlx5/core/health.c > > > index f9438d4e43ca..81ca44e0705a 100644 > > > --- a/drivers/net/ethernet/mellanox/mlx5/core/health.c > > > +++ b/drivers/net/ethernet/mellanox/mlx5/core/health.c > > > @@ -325,6 +325,8 @@ int mlx5_health_wait_pci_up(struct mlx5_core_dev *dev) > > > while (sensor_pci_not_working(dev)) { > > > > According to the comment in sensor_pci_not_working(), this loop is > > supposed to wait till PCI will be ready again. Otherwise, already in > > first iteration, we will bail out with pci_channel_offline() error. > > Well yes. The problem is that this works for intermittent errors > including when the card resets itself which seems to be the use case in > mlx5_fw_reset_complete_reload() and mlx5_devlink_reload_fw_activate(). > If there is a PCI error that requires a link reset though we see some > problems though it does work after running into the timeout. > > As I understand it and as implemented at least on s390, > pci_channel_io_frozen is only set for fatal errors that require a reset > while non fatal errors will have pci_channel_io_normal (see also > Documentation/PCI/pcieaer-howto.rst) Yes, I think that's true, see handle_error_source(). > thus I think pci_channel_offline() > should only be true if a reset is required or there is a permanent > error. Yes, I think pci_channel_offline() will only be true when a fatal error has been reported via AER or DPC (or a hotplug driver says the device has been removed). The driver resetting the device should not cause such a fatal error. > Furthermore in the pci_channel_io_frozen state the PCI function > may be isolated and the reads will not reach the endpoint, this is the > case at least on s390. Thus for errors requiring a reset the loop > without pci_channel_offline() will run until the reset is performed or > the timeout is reached. In the mlx5_health_try_recover() case during > error recovery we will then indeed always loop until timeout, because > the loop blocks mlx5_pci_err_detected() from returning thus blocking > the reset (see Documentation/PCI/pci-error-recovery.rst). Adding Bjorn, > maybe he can confirm or correct my assumptions here. > > > if (time_after(jiffies, end)) > > > return -ETIMEDOUT; > > > + if (pci_channel_offline(dev->pdev)) > > > + return -EIO; > > > msleep(100); > > > } > > > return 0; > > > @@ -332,10 +334,16 @@ int mlx5_health_wait_pci_up(struct mlx5_core_dev *dev) > > > > > > static int mlx5_health_try_recover(struct mlx5_core_dev *dev) > > > { > > > + int rc; > > > + > > > mlx5_core_warn(dev, "handling bad device here\n"); > > > mlx5_handle_bad_state(dev); > > > - if (mlx5_health_wait_pci_up(dev)) { > > > - mlx5_core_err(dev, "health recovery flow aborted, PCI reads still not working\n"); > > > + rc = mlx5_health_wait_pci_up(dev); > > > + if (rc) { > > > + if (rc == -ETIMEDOUT) > > > + mlx5_core_err(dev, "health recovery flow aborted, PCI reads still not working\n"); > > > + else > > > + mlx5_core_err(dev, "health recovery flow aborted, PCI channel offline\n"); > > > return -EIO; > > > } > > > mlx5_core_err(dev, "starting health recovery flow\n"); > > > > > > base-commit: 7e364e56293bb98cae1b55fd835f5991c4e96e7d > > > -- > > > 2.37.2 > > > >
On Wed, Apr 05, 2023 at 04:06:13PM -0500, Bjorn Helgaas wrote: > On Tue, Apr 04, 2023 at 05:27:35PM +0200, Niklas Schnelle wrote: > > On Mon, 2023-04-03 at 21:21 +0300, Leon Romanovsky wrote: > > > On Mon, Apr 03, 2023 at 09:56:56AM +0200, Niklas Schnelle wrote: > > > > after an error on the PCI link, the driver does not need to wait > > > > for the link to become functional again as a reset is required. Stop > > > > the wait loop in this case to accelerate the recovery flow. > > > > > > > > Co-developed-by: Alexander Schmidt <alexs@linux.ibm.com> > > > > Signed-off-by: Alexander Schmidt <alexs@linux.ibm.com> > > > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > > > > --- > > > > drivers/net/ethernet/mellanox/mlx5/core/health.c | 12 ++++++++++-- > > > > 1 file changed, 10 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/health.c b/drivers/net/ethernet/mellanox/mlx5/core/health.c > > > > index f9438d4e43ca..81ca44e0705a 100644 > > > > --- a/drivers/net/ethernet/mellanox/mlx5/core/health.c > > > > +++ b/drivers/net/ethernet/mellanox/mlx5/core/health.c > > > > @@ -325,6 +325,8 @@ int mlx5_health_wait_pci_up(struct mlx5_core_dev *dev) > > > > while (sensor_pci_not_working(dev)) { > > > > > > According to the comment in sensor_pci_not_working(), this loop is > > > supposed to wait till PCI will be ready again. Otherwise, already in > > > first iteration, we will bail out with pci_channel_offline() error. > > > > Well yes. The problem is that this works for intermittent errors > > including when the card resets itself which seems to be the use case in > > mlx5_fw_reset_complete_reload() and mlx5_devlink_reload_fw_activate(). > > If there is a PCI error that requires a link reset though we see some > > problems though it does work after running into the timeout. > > > > As I understand it and as implemented at least on s390, > > pci_channel_io_frozen is only set for fatal errors that require a reset > > while non fatal errors will have pci_channel_io_normal (see also > > Documentation/PCI/pcieaer-howto.rst) > > Yes, I think that's true, see handle_error_source(). > > > thus I think pci_channel_offline() > > should only be true if a reset is required or there is a permanent > > error. > > Yes, I think pci_channel_offline() will only be true when a fatal > error has been reported via AER or DPC (or a hotplug driver says the > device has been removed). The driver resetting the device should not > cause such a fatal error. Thank you for an explanation and confirmation.
On Mon, Apr 03, 2023 at 09:56:56AM +0200, Niklas Schnelle wrote: > after an error on the PCI link, the driver does not need to wait > for the link to become functional again as a reset is required. Stop > the wait loop in this case to accelerate the recovery flow. > > Co-developed-by: Alexander Schmidt <alexs@linux.ibm.com> > Signed-off-by: Alexander Schmidt <alexs@linux.ibm.com> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > --- > drivers/net/ethernet/mellanox/mlx5/core/health.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > The subject line should include target for netdev patches: [PATCH net-next] .... Thanks, Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
On Sun, 2023-04-09 at 11:55 +0300, Leon Romanovsky wrote: > On Mon, Apr 03, 2023 at 09:56:56AM +0200, Niklas Schnelle wrote: > > after an error on the PCI link, the driver does not need to wait > > for the link to become functional again as a reset is required. Stop > > the wait loop in this case to accelerate the recovery flow. > > > > Co-developed-by: Alexander Schmidt <alexs@linux.ibm.com> > > Signed-off-by: Alexander Schmidt <alexs@linux.ibm.com> > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > > --- > > drivers/net/ethernet/mellanox/mlx5/core/health.c | 12 ++++++++++-- > > 1 file changed, 10 insertions(+), 2 deletions(-) > > > > The subject line should include target for netdev patches: [PATCH net-next] .... > > Thanks, > Reviewed-by: Leon Romanovsky <leonro@nvidia.com> Thanks, I'll sent a v2 with your R-b, the correct net-next prefix and a Link to this discussion.
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/health.c b/drivers/net/ethernet/mellanox/mlx5/core/health.c index f9438d4e43ca..81ca44e0705a 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/health.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/health.c @@ -325,6 +325,8 @@ int mlx5_health_wait_pci_up(struct mlx5_core_dev *dev) while (sensor_pci_not_working(dev)) { if (time_after(jiffies, end)) return -ETIMEDOUT; + if (pci_channel_offline(dev->pdev)) + return -EIO; msleep(100); } return 0; @@ -332,10 +334,16 @@ int mlx5_health_wait_pci_up(struct mlx5_core_dev *dev) static int mlx5_health_try_recover(struct mlx5_core_dev *dev) { + int rc; + mlx5_core_warn(dev, "handling bad device here\n"); mlx5_handle_bad_state(dev); - if (mlx5_health_wait_pci_up(dev)) { - mlx5_core_err(dev, "health recovery flow aborted, PCI reads still not working\n"); + rc = mlx5_health_wait_pci_up(dev); + if (rc) { + if (rc == -ETIMEDOUT) + mlx5_core_err(dev, "health recovery flow aborted, PCI reads still not working\n"); + else + mlx5_core_err(dev, "health recovery flow aborted, PCI channel offline\n"); return -EIO; } mlx5_core_err(dev, "starting health recovery flow\n");