PCI: hotplug: Drop superfluous try_module_get() calls

In December 2002, historic commit

  https://git.kernel.org/tglx/history/c/bec7aa00ffe5
  ("[PATCH] more module warning fixes")

amended the PCI hotplug core to acquire a reference on the hotplug
driver module when a sysfs attribute is accessed.  That was necessary
because back in the day, sysfs code did not take any precautions to
prevent module unloading when an attribute was accessed.

Soon after in July 2003, historic commit

  https://git.kernel.org/tglx/history/c/1cf6d20f6078
  ("[PATCH] SYSFS: add module referencing to sysfs attribute files.")

addressed that deficiency.  But the commit neglected to remove the now
unnecessary reference acquisition from the PCI hotplug core.

The commit acquired a module reference for the entire duration between
open() and close() of a sysfs attribute.  This made it impossible to
unload a module while attributes were kept open by user space.
That's possible today:

When a hotplug driver module is unloaded, it removes sysfs attributes of
all its hotplug slots by calling pci_hp_del().  This will wait for any
concurrent user space operation to finish:

  pci_hp_del()
    fs_remove_slot()
      sysfs_remove_file()
        sysfs_remove_file_ns()
          kernfs_remove_by_name_ns()
            __kernfs_remove()
              kernfs_drain()

A user space operation such as read() briefly acquires a reference on
the attribute with kernfs_get_active().  kernfs_drain() waits until all
such references are released before allowing attribute removal.  Once
the attribute is removed, any subsequent user space operation on a still
open attribute file will return -ENODEV.

Thus, reference acquisition by the PCI hotplug core is still unnecessary
today.  So drop it at long last.

Link: https://lore.kernel.org/r/ed950fa2722967be4491146c7b867c1e7be11d37.1740501868.git.lukas@wunner.de
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

0 files changed, 0 insertions, 0 deletions