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i2c: i801: Use PCI bus rescan mutex to protect P2SB access

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[ 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>
This commit is contained in:
Heiner Kallweit 2021-09-05 17:59:42 +02:00 committed by Greg Kroah-Hartman
parent aad5b030fa
commit c31b0fe8e1
1 changed files with 2 additions and 3 deletions
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5
drivers/i2c/busses/i2c-i801.c
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@ -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)