2018-06-04 15:48:53

by Alexandru Gagniuc

Subject: [PATCH] PCI: access.c: Piggyback user config access on pci_read/write_*()

pci_read/write_config*() functions have several safeguards to prevent
stallling accesses when a device is removed. However, their "_user_"
counterparts use a different code path.

To make sure that safeguards are used for userspace PCI config
accesses, piggyback the "_user_" functions on the in-kernel
pci_read/write_config*().

Signed-off-by: Alexandru Gagniuc <[email protected]>
---
drivers/pci/access.c | 16 ++--------------
1 file changed, 2 insertions(+), 14 deletions(-)

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index a3ad2fe185b9..6db2a8713c85 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -223,16 +223,9 @@ int pci_user_read_config_##size \
(struct pci_dev *dev, int pos, type *val) \
{ \
int ret = PCIBIOS_SUCCESSFUL; \
- u32 data = -1; \
if (PCI_##size##_BAD) \
return -EINVAL; \
- raw_spin_lock_irq(&pci_lock); \
- if (unlikely(dev->block_cfg_access)) \
- pci_wait_cfg(dev); \
- ret = dev->bus->ops->read(dev->bus, dev->devfn, \
- pos, sizeof(type), &data); \
- raw_spin_unlock_irq(&pci_lock); \
- *val = (type)data; \
+ ret = pci_read_config_##size(dev, pos, val); \
return pcibios_err_to_errno(ret); \
} \
EXPORT_SYMBOL_GPL(pci_user_read_config_##size);
@@ -245,12 +238,7 @@ int pci_user_write_config_##size \
int ret = PCIBIOS_SUCCESSFUL; \
if (PCI_##size##_BAD) \
return -EINVAL; \
- raw_spin_lock_irq(&pci_lock); \
- if (unlikely(dev->block_cfg_access)) \
- pci_wait_cfg(dev); \
- ret = dev->bus->ops->write(dev->bus, dev->devfn, \
- pos, sizeof(type), val); \
- raw_spin_unlock_irq(&pci_lock); \
+ ret = pci_write_config_##size(dev, pos, val); \
return pcibios_err_to_errno(ret); \
} \
EXPORT_SYMBOL_GPL(pci_user_write_config_##size);
--
2.14.4

2018-06-04 16:10:20

by Keith Busch

Subject: Re: [PATCH] PCI: access.c: Piggyback user config access on pci_read/write_*()

On Mon, Jun 04, 2018 at 10:48:02AM -0500, Alexandru Gagniuc wrote:
> +++ b/drivers/pci/access.c
> @@ -223,16 +223,9 @@ int pci_user_read_config_##size \
> (struct pci_dev *dev, int pos, type *val) \
> { \
> int ret = PCIBIOS_SUCCESSFUL; \
> - u32 data = -1; \
> if (PCI_##size##_BAD) \
> return -EINVAL; \
> - raw_spin_lock_irq(&pci_lock); \
> - if (unlikely(dev->block_cfg_access)) \
> - pci_wait_cfg(dev); \
> - ret = dev->bus->ops->read(dev->bus, dev->devfn, \
> - pos, sizeof(type), &data); \
> - raw_spin_unlock_irq(&pci_lock); \
> - *val = (type)data; \
> + ret = pci_read_config_##size(dev, pos, val); \
> return pcibios_err_to_errno(ret); \
> } \

If it wasn't for the block_cfg_access check for user access, this would
have been a nice code reuse cleanup.

2018-06-04 16:15:18

by Alex_Gagniuc

Subject: Re: [PATCH] PCI: access.c: Piggyback user config access on pci_read/write_*()

On 6/4/2018 11:09 AM, Keith Busch wrote:
> On Mon, Jun 04, 2018 at 10:48:02AM -0500, Alexandru Gagniuc wrote:
>> +++ b/drivers/pci/access.c
>> @@ -223,16 +223,9 @@ int pci_user_read_config_##size \
>> (struct pci_dev *dev, int pos, type *val) \
>> { \
>> int ret = PCIBIOS_SUCCESSFUL; \
>> - u32 data = -1; \
>> if (PCI_##size##_BAD) \
>> return -EINVAL; \
>> - raw_spin_lock_irq(&pci_lock); \
>> - if (unlikely(dev->block_cfg_access)) \
>> - pci_wait_cfg(dev); \
>> - ret = dev->bus->ops->read(dev->bus, dev->devfn, \
>> - pos, sizeof(type), &data); \
>> - raw_spin_unlock_irq(&pci_lock); \
>> - *val = (type)data; \
>> + ret = pci_read_config_##size(dev, pos, val); \
>> return pcibios_err_to_errno(ret); \
>> } \
>
> If it wasn't for the block_cfg_access check for user access, this would
> have been a nice code reuse cleanup.

Great fresh catch! I'll get that fixed in v2.

Alex