On Wed, Jan 29, 2020 at 06:29:13PM +0300, Sergei Miroshnichenko wrote:
> The PCI_COMMAND_IO and PCI_COMMAND_MEMORY bits of the bridge must be
> updated not only when enabling the bridge for the first time, but also if a
> hotplugged device requests these types of resources.
>
> For example, if a bridge had all its slots empty, the IO and MEM bits will
> not be set, and a hot hotplugged device will fail.
s/hot hotplugged/hot-added/ or something similar
> Originally these bits were set by the pci_enable_device_flags() only, which
> exits early if the bridge is already pci_is_enabled(). So let's check them
> again when requested.
s/by the/by/
s/ only,/,
IIUC, in the current tree (before this series), we do set
PCI_COMMAND_IO and PCI_COMMAND_MEMORY on bridges leading to hot-added
devices, but this patch is needed because [01/26] "PCI: Fix race
condition in pci_enable/disable_device()" makes
pci_enable_device_flags() exit early without setting those bits.
That would mean there's a bisection hole between [01/26] and [02/26]
where hot-added devices will fail. We don't want a hole like that.
> Signed-off-by: Sergei Miroshnichenko <s.miroshnichenko@xxxxxxxxx>
> ---
> drivers/pci/pci.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 0366289c75e9..cb0042f28e6a 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1679,6 +1679,14 @@ static void pci_enable_bridge(struct pci_dev *dev)
> pci_enable_bridge(bridge);
>
> if (pci_is_enabled(dev)) {
> + int i, bars = 0;
> +
> + for (i = PCI_BRIDGE_RESOURCES; i < DEVICE_COUNT_RESOURCE; i++) {
> + if (dev->resource[i].flags & (IORESOURCE_MEM | IORESOURCE_IO))
> + bars |= (1 << i);
> + }
> + do_pci_enable_device(dev, bars);
> +
> if (!dev->is_busmaster)
> pci_set_master(dev);
> mutex_unlock(&dev->enable_mutex);
> --
> 2.24.1
>
