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


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