PCI driver module unload race?

Russell King
2003-03-08T19:53:31Z

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.

- 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.

Comments?

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