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    SubjectRe: PCI driver module unload race?
    On Sat, Mar 08, 2003 at 10:47:49AM +0000, Russell King wrote:
    > Hi,
    >
    > What prevents the following scenario from happening? It's purely
    > theoretical - I haven't seen this occuring.
    >
    > - Load PCI driver.
    >
    > - PCI driver registers using pci_module_init(), and adds itself to sysfs.
    >
    > - Hot-plugin a PCI device which uses this driver. sysfs matches the PCI
    > driver, and calls the PCI drivers probe function.

    Ugh, yes you are correct, I can't believe I missed this before.

    How does this patch look?

    thanks,

    greg k-h


    ===== drivers/pci/pci-driver.c 1.17 vs edited =====
    --- 1.17/drivers/pci/pci-driver.c Sat Nov 23 13:23:03 2002
    +++ edited/drivers/pci/pci-driver.c Sat Mar 8 11:21:06 2003
    @@ -48,6 +48,12 @@
    if (!pci_dev->driver && drv->probe) {
    const struct pci_device_id *id;

    + if (!try_module_get(drv->owner)) {
    + dev_err(dev, "Can't get a module reference for %s\n",
    + drv->name);
    + error = -ENODEV;
    + goto exit;
    + }
    id = pci_match_device(drv->id_table, pci_dev);
    if (id)
    error = drv->probe(pci_dev, id);
    @@ -55,7 +61,9 @@
    pci_dev->driver = drv;
    error = 0;
    }
    + module_put(drv->owner);
    }
    +exit:
    return error;
    }

    @@ -66,7 +74,10 @@

    if (drv) {
    if (drv->remove)
    - drv->remove(pci_dev);
    + if (try_module_get(drv->owner)) {
    + drv->remove(pci_dev);
    + module_put(drv->owner);
    + }
    pci_dev->driver = NULL;
    }
    return 0;
    ===== include/linux/pci.h 1.36 vs edited =====
    --- 1.36/include/linux/pci.h Tue Mar 4 21:09:58 2003
    +++ edited/include/linux/pci.h Sat Mar 8 11:20:15 2003
    @@ -493,6 +493,7 @@

    struct pci_driver {
    struct list_head node;
    + struct module *owner;
    char *name;
    const struct pci_device_id *id_table; /* NULL if wants all devices */
    int (*probe) (struct pci_dev *dev, const struct pci_device_id *id); /* New device inserted */
    -
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