Re: [PATCH 3/4] PCI: Remove reset_fn field from pci_dev

Pali Rohár
2021-03-14T23:53:32Z

On Friday 12 March 2021 23:04:51 ameynarkhede03@gmail.com wrote:
> From: Amey Narkhede <ameynarkhede03@gmail.com>
>
> reset_fn field is used to indicate whether the
> device supports any reset mechanism or not.
> Deprecate use of reset_fn in favor of new
> reset_methods bitmap which can be used to keep
> track of all supported reset mechanisms of a device.

Hello Amey!

You cannot trigger PCIe Hot Reset (PCI secondary bus reset) in this
simple way from sysfs via new reset methods.

I proposed very similar functionality just few days ago:
https://lore.kernel.org/linux-pci/20210301171221.3d42a55i7h5ubqsb@pali/T/#u

And I realized that it needs more steps to be done.

At least some remove-reset-rescan procedure done atomically is required.

> Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.com>
> ---
> Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
> Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
>
> drivers/net/ethernet/cavium/liquidio/lio_vf_main.c | 2 +-
> drivers/pci/pci-sysfs.c | 6 ++----
> drivers/pci/pci.c | 6 +++---
> drivers/pci/probe.c | 1 -
> drivers/pci/quirks.c | 2 +-
> include/linux/pci.h | 1 -
> 6 files changed, 7 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c b/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c
> index 9b9d305c6..3e2c49e08 100644
> --- a/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c
> +++ b/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c
> @@ -526,7 +526,7 @@ static void octeon_destroy_resources(struct octeon_device *oct)
> oct->irq_name_storage = NULL;
> }
> /* Soft reset the octeon device before exiting */
> - if (oct->pci_dev->reset_fn)
> + if (oct->pci_dev->reset_methods)
> octeon_pci_flr(oct);
> else
> cn23xx_vf_ask_pf_to_do_flr(oct);
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index f8afd54ca..78d2c130c 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -1334,7 +1334,7 @@ static int pci_create_capabilities_sysfs(struct pci_dev *dev)
>
> pcie_vpd_create_sysfs_dev_files(dev);
>
> - if (dev->reset_fn) {
> + if (dev->reset_methods) {
> retval = device_create_file(&dev->dev, &dev_attr_reset);
> if (retval)
> goto error;
> @@ -1417,10 +1417,8 @@ int __must_check pci_create_sysfs_dev_files(struct pci_dev *pdev)
> static void pci_remove_capabilities_sysfs(struct pci_dev *dev)
> {
> pcie_vpd_remove_sysfs_dev_files(dev);
> - if (dev->reset_fn) {
> + if (dev->reset_methods)
> device_remove_file(&dev->dev, &dev_attr_reset);
> - dev->reset_fn = 0;
> - }
> }
>
> /**
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 407b44e85..b7f6c6588 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5175,7 +5175,7 @@ int pci_reset_function(struct pci_dev *dev)
> {
> int rc;
>
> - if (!dev->reset_fn)
> + if (!dev->reset_methods)
> return -ENOTTY;
>
> pci_dev_lock(dev);
> @@ -5211,7 +5211,7 @@ int pci_reset_function_locked(struct pci_dev *dev)
> {
> int rc;
>
> - if (!dev->reset_fn)
> + if (!dev->reset_methods)
> return -ENOTTY;
>
> pci_dev_save_and_disable(dev);
> @@ -5234,7 +5234,7 @@ int pci_try_reset_function(struct pci_dev *dev)
> {
> int rc;
>
> - if (!dev->reset_fn)
> + if (!dev->reset_methods)
> return -ENOTTY;
>
> if (!pci_dev_trylock(dev))
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 01dd037bd..4764e031a 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2404,7 +2404,6 @@ static void pci_init_capabilities(struct pci_dev *dev)
>
> pcie_report_downtraining(dev);
> pci_init_reset_methods(dev);
> - dev->reset_fn = !!dev->reset_methods;
> }
>
> /*
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 0a3df84c9..20a81b1bc 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -5535,7 +5535,7 @@ static void quirk_reset_lenovo_thinkpad_p50_nvgpu(struct pci_dev *pdev)
>
> if (pdev->subsystem_vendor != PCI_VENDOR_ID_LENOVO ||
> pdev->subsystem_device != 0x222e ||
> - !pdev->reset_fn)
> + !pdev->reset_methods)
> return;
>
> if (pci_enable_device_mem(pdev))
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 56d6e4750..a2f003f4e 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -437,7 +437,6 @@ struct pci_dev {
> unsigned int state_saved:1;
> unsigned int is_physfn:1;
> unsigned int is_virtfn:1;
> - unsigned int reset_fn:1;
> unsigned int is_hotplug_bridge:1;
> unsigned int shpc_managed:1; /* SHPC owned by shpchp */
> unsigned int is_thunderbolt:1; /* Thunderbolt controller */
> --
> 2.30.2