PCI driver module unload race?

Russell King (rmk@arm.linux.org.uk)
Sat, 8 Mar 2003 10:47:49 +0000


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.

- The probe function calls kmalloc or some other function which sleeps
(or gets preempted, if CONFIG_PREEMPT is enabled.)

- We switch to another thread, which happens to be rmmod for this PCI
driver. We remove the driver since it has a use count of zero.

- We switch back to the PCI driver. Oops.

I've probably missed something, but I don't think so. I suspect we need
struct device_driver to include a struct module pointer which sysfs can
take before calling any driver functions.


Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux

- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/