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Commit a96d627a authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk
Browse files

pci: Introduce __pci_reset_function_locked to be used when holding device_lock. 



The use case of this is when a driver wants to call FLR when a device
is attached to it using the SysFS "bind" or "unbind" functionality.

The call chain when a user does "bind" looks as so:

 echo "0000:01.07.0" > /sys/bus/pci/drivers/XXXX/bind

and ends up calling:
  driver_bind:
    device_lock(dev);  <=== TAKES LOCK
    XXXX_probe:
         .. pci_enable_device()
         ...__pci_reset_function(), which calls
                 pci_dev_reset(dev, 0):
                        if (!0) {
                                device_lock(dev) <==== DEADLOCK

The __pci_reset_function_locked function allows the the drivers
'probe' function to call the "pci_reset_function" while still holding
the driver mutex lock.

Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 8605c684

drivers/pci/pci.c

+25 −0
Original line number Diff line number Diff line
@@ -3162,6 +3162,31 @@ int __pci_reset_function(struct pci_dev *dev) 
}

EXPORT_SYMBOL_GPL(__pci_reset_function);



/**

 * __pci_reset_function_locked - reset a PCI device function while holding

 * the @dev mutex lock.

 * @dev: PCI device to reset

 *

 * Some devices allow an individual function to be reset without affecting

 * other functions in the same device.  The PCI device must be responsive

 * to PCI config space in order to use this function.

 *

 * The device function is presumed to be unused and the caller is holding

 * the device mutex lock when this function is called.

 * Resetting the device will make the contents of PCI configuration space

 * random, so any caller of this must be prepared to reinitialise the

 * device including MSI, bus mastering, BARs, decoding IO and memory spaces,

 * etc.

 *

 * Returns 0 if the device function was successfully reset or negative if the

 * device doesn't support resetting a single function.

 */

int __pci_reset_function_locked(struct pci_dev *dev)

{

	return pci_dev_reset(dev, 1);

}

EXPORT_SYMBOL_GPL(__pci_reset_function_locked);



/**

 * pci_probe_reset_function - check whether the device can be safely reset

 * @dev: PCI device to reset

include/linux/pci.h

+1 −0
Original line number Diff line number Diff line
@@ -817,6 +817,7 @@ int pcie_set_readrq(struct pci_dev *dev, int rq); 
int pcie_get_mps(struct pci_dev *dev);

int pcie_set_mps(struct pci_dev *dev, int mps);

int __pci_reset_function(struct pci_dev *dev);

int __pci_reset_function_locked(struct pci_dev *dev);

int pci_reset_function(struct pci_dev *dev);

void pci_update_resource(struct pci_dev *dev, int resno);

int __must_check pci_assign_resource(struct pci_dev *dev, int i);