Hi Yijing,
On 02/12/2014 10:52 AM, Yijing Wang wrote:
> Pci_dummy_ops does nothing when we use it to read/write
> pci_device. So we can isolate pci device by replace its
> bus pci_ops by pci_dummy_ops. This is preparation for
> the later patch.
>
> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
> ---
> drivers/pci/pci.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/pci.h | 4 +++
> 2 files changed, 66 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index af34057..283e82e 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2226,6 +2226,68 @@ bool pci_serial_number_changed(struct pci_dev *pdev)
> }
> EXPORT_SYMBOL(pci_serial_number_changed);
>
> +static int pci_dummy_read(struct pci_bus *bus, unsigned int devfn,
> + int where, int size, u32 *val)
> +{
> + return PCIBIOS_DEVICE_NOT_FOUND;
> +}
> +
> +static int pci_dummy_write(struct pci_bus *bus, unsigned int devfn,
> + int reg, int size, u32 val)
> +{
> + return PCIBIOS_DEVICE_NOT_FOUND;
> +}
> +
> +static struct pci_ops pci_dummy_ops = {
> + .read = pci_dummy_read,
> + .write = pci_dummy_write,
> +};
> +
> +static DEFINE_SPINLOCK(pci_freeze_lock);
> +/**
> + * pci_bus_freeze_device - freeze pci bus to access pci device
> + * @bus: the pci bus to freeze
> + *
> + * Replace pci bus ops by pci_dummy_ops, protect system from
> + * accessing pci devices.
> + */
> +void pci_bus_freeze_device(struct pci_bus *bus)
> +{
> + struct pci_ops *ops;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&pci_freeze_lock, flags);
> + if (bus->is_frozen)
> + goto out;
> + bus->is_frozen = 1;
> + ops = pci_bus_set_ops(bus, &pci_dummy_ops);
> + bus->save_ops = ops;
> +out:
> + spin_unlock_irqrestore(&pci_freeze_lock, flags);
> +}
> +
> +/**
> + * pci_bus_unfreeze_device - unfreeze pci bus to acess pci devices
> + * @bus: the pci bus to unfreeze
> + *
> + * Restore pci bus original ops, so pci bus can access
> + * pci devices normally.
> + */
> +void pci_bus_unfreeze_device(struct pci_bus *bus)
> +{
> + unsigned long flags;
> +
> + BUG_ON(!bus->save_ops);
> + spin_lock_irqsave(&pci_freeze_lock, flags);
> + if (!bus->is_frozen)
> + goto out;
It seems that the BUG_ON() should placed here, otherwise it will be
triggered if we try to unfreeze the same bus multiply.
Regards,
Gu
> + pci_bus_set_ops(bus, bus->save_ops);
> + bus->save_ops = NULL;
> + bus->is_frozen = 0;
> +out:
> + spin_unlock_irqrestore(&pci_freeze_lock, flags);
> +}
> +
> /**
> * pci_configure_ari - enable or disable ARI forwarding
> * @dev: the PCI device
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index d60c0b6..e3dd4ea 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -442,6 +442,7 @@ struct pci_bus {
> struct resource busn_res; /* bus numbers routed to this bus */
>
> struct pci_ops *ops; /* configuration access functions */
> + struct pci_ops *save_ops; /* save configuration access functions */
> struct msi_chip *msi; /* MSI controller */
> void *sysdata; /* hook for sys-specific extension */
> struct proc_dir_entry *procdir; /* directory entry in /proc/bus/pci */
> @@ -460,6 +461,7 @@ struct pci_bus {
> struct bin_attribute *legacy_io; /* legacy I/O for this bus */
> struct bin_attribute *legacy_mem; /* legacy mem */
> unsigned int is_added:1;
> + unsigned int is_frozen:1;
> };
>
> #define pci_bus_b(n) list_entry(n, struct pci_bus, node)
> @@ -1026,6 +1028,8 @@ ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf);
> ssize_t pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count, const void *buf);
>
> bool pci_serial_number_changed(struct pci_dev *pdev);
> +void pci_bus_freeze_device(struct pci_bus *bus);
> +void pci_bus_unfreeze_device(struct pci_bus *bus);
>
> /* Helper functions for low-level code (drivers/pci/setup-[bus,res].c) */
> resource_size_t pcibios_retrieve_fw_addr(struct pci_dev *dev, int idx);
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