[PATCH 5.15 701/917] i2c: i801: Use PCI bus rescan mutex to protect P2SB access

Greg Kroah-Hartman
2021-11-16T00:00:10Z

From: Heiner Kallweit <hkallweit1@gmail.com>

[ Upstream commit 7d6b61c394a42b8385858bb9e306d48a0112823c ]

As pointed out by Andy in [0] using a local mutex here isn't strictly
wrong but not sufficient. We should hold the PCI rescan lock for P2SB
operations.

[0] https://www.spinics.net/lists/linux-i2c/msg52717.html

Fixes: 1a987c69ce2c ("i2c: i801: make p2sb_spinlock a mutex")
Reported-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/i2c/busses/i2c-i801.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 89ae78ef1a1cc..1f929e6c30bea 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -1493,7 +1493,6 @@ static struct platform_device *
i801_add_tco_spt(struct i801_priv *priv, struct pci_dev *pci_dev,
struct resource *tco_res)
{
- static DEFINE_MUTEX(p2sb_mutex);
struct resource *res;
unsigned int devfn;
u64 base64_addr;
@@ -1506,7 +1505,7 @@ i801_add_tco_spt(struct i801_priv *priv, struct pci_dev *pci_dev,
* enumerated by the PCI subsystem, so we need to unhide/hide it
* to lookup the P2SB BAR.
*/
- mutex_lock(&p2sb_mutex);
+ pci_lock_rescan_remove();

devfn = PCI_DEVFN(PCI_SLOT(pci_dev->devfn), 1);

@@ -1524,7 +1523,7 @@ i801_add_tco_spt(struct i801_priv *priv, struct pci_dev *pci_dev,
/* Hide the P2SB device, if it was hidden before */
if (hidden)
pci_bus_write_config_byte(pci_dev->bus, devfn, 0xe1, hidden);
- mutex_unlock(&p2sb_mutex);
+ pci_unlock_rescan_remove();

res = &tco_res[1];
if (pci_dev->device == PCI_DEVICE_ID_INTEL_DNV_SMBUS)
--
2.33.0