pinctrl: generic: serialise pinctrl_generic_dt_node_to_map()

pinctrl_generic_add_group() documents that the caller must take care of
locking, and pinmux_generic_add_function() needs it too, but
pinctrl_generic_dt_node_to_map() calls them without holding
pctldev->mutex, and the core caller in create_pinctrl() does not take it
either.

The driver core calls pinctrl_bind_pins() before probing a device, so
two devices that reference the same pin controller can run
pinctrl_generic_dt_node_to_map() on one pctldev at the same time.

Both `add` functions take the new selector from pctldev->num_groups or
pctldev->num_functions, and radix_tree_insert() at that index.
Two racing callers can read the same selector before either
has inserted, so the second insert collides and fails:

  k1-pinctrl d401e000.pinctrl:
  error -EEXIST: error adding function pcie2-0-cfg
  k1-pinctrl d401e000.pinctrl:
  does not have pin group pcie0-0-cfg.pcie0-0-pins

leaving one consumer without its pin configuration.

This was hit on a SpacemiT K3 board, where PCIe devices probe in parallel
against the single shared pin controller.

Take pctldev->mutex across the whole function, so that the groups and the
function referring are in a single critical section.

Fixes: 43722575e5cd ("pinctrl: add generic functions + pins mapper")
Signed-off-by: Sarah Emery <sarah.emery@canonical.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>

0 files changed, 0 insertions, 0 deletions