Messages in this thread | | | Date | Wed, 20 Mar 2013 10:23:50 -0600 | From | Stephen Warren <> | Subject | Re: [PATCH] BUG: [RFC] pinctrl: pins are freed 2 times in pinctrl_bind_pins |
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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!
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