Messages in this thread | | | From | Richard Genoud <> | Date | Thu, 21 Mar 2013 12:31:44 +0100 | Subject | Re: [PATCH] BUG: [RFC] pinctrl: pins are freed 2 times in pinctrl_bind_pins |
| |
2013/3/20 Stephen Warren <swarren@wwwdotorg.org>: > On 03/20/2013 05:31 AM, Richard Genoud wrote: >> If the function pinctrl_select_state() fails because one pin is already >> taken elsewhere, pinmux_enable_setting makes all the necessary pin_free >> calls (and not more than necessary). >> The problem here is that devm_pinctrl_put() will be called on the pin >> group, and each pin in this group has already been freed. >> >> Example: >> If a i2c function has already sucessfully taken pins 5 and 6. >> And now, pinctrl_bind_pins() is called for function PHY (pins 3 4 5 6 7). >> pinmux_enable_setting() will fail AND call pin_free on necessary pins. >> But if devm_pinctrl_put() is called, it will call again pin_free on pins >> 3 4 5 6 7. >> So, the pins 5 and 6 will be released (and pins 3 4 7 double freed). >> Which means that even if the i2c function has claim the pins, they will >> be available for other functions. >> >> This patch simply doesn't call devm_pinctrl_put when >> pinctrl_select_state fails, but I'm not sure it's the right thing to do. > > The correct fix here is not to skip the call to devm_pinctrl_put(), > since that undoes a lot of other things besides the current state selection. > > Instead, pinctrl_select_state_locked() needs to be fixed so that: > > a) > > Change "p->state = state;" to "p->state = NULL;" or similar, to indicate > that no state is selected. (Please validate if a NULL value in that > variable will cause problems elsewhere) > > b) > > Add back the assignment "p->state = state;" at the end of the function, > if no error occurred. > > c) > > Fix the list_for_each_entry() call that applies all the settings for the > new state so that if it fails, it undoes everything that it's applied so > far. That's the hard part, unless there's a > list_for_each_entry_before_the_current_one_that_list_for_each_entry_iterated_over_already() > macro! ok, I'll look into that. Thanks for your advices !
PS: with its 90chars long, your macro won't please checkpatch.pl ! :)
Regards, Richard
| |