• Doug Anderson's avatar
    pinctrl: Don't just pretend to protect pinctrl_maps, do it for real · a9afea63
    Doug Anderson authored
    commit c5272a28 upstream.
    
    Way back, when the world was a simpler place and there was no war, no
    evil, and no kernel bugs, there was just a single pinctrl lock.  That
    was how the world was when (57291ce2 pinctrl: core device tree mapping
    table parsing support) was written.  In that case, there were
    instances where the pinctrl mutex was already held when
    pinctrl_register_map() was called, hence a "locked" parameter was
    passed to the function to indicate that the mutex was already locked
    (so we shouldn't lock it again).
    
    A few years ago in (42fed7ba pinctrl: move subsystem mutex to
    pinctrl_dev struct), we switched to a separate pinctrl_maps_mutex.
    ...but (oops) we forgot to re-think about the whole "locked" parameter
    for pinctrl_register_map().  Basically the "locked" parameter appears
    to still refer to whether the bigger pinctrl_dev mutex is locked, but
    we're using it to skip locks of our (now separate) pinctrl_maps_mutex.
    
    That's kind of a bad thing(TM).  Probably nobody noticed because most
    of the calls to pinctrl_register_map happen at boot time and we've got
    synchronous device probing.  ...and even cases where we're
    asynchronous don't end up actually hitting the race too often.  ...but
    after banging my head against the wall for a bug that reproduced 1 out
    of 1000 reboots and lots of looking through kgdb, I finally noticed
    this.
    
    Anyway, we can now safely remove the "locked" parameter and go back to
    a war-free, evil-free, and kernel-bug-free world.
    
    Fixes: 42fed7ba ("pinctrl: move subsystem mutex to pinctrl_dev struct")
    Signed-off-by: default avatarDoug Anderson <dianders@chromium.org>
    Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
    Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
    a9afea63
core.c 45.6 KB