Hi Jean-Jacques, On Sat, Mar 4, 2023 at 11:34 AM Jean-Jacques Hiblot <jjhiblot@xxxxxxxxxxxxxxx> wrote: > On 02/03/2023 08:49, Geert Uytterhoeven wrote: > > On Wed, Mar 1, 2023 at 7:53 PM Jean-Jacques Hiblot > > <jjhiblot@xxxxxxxxxxxxxxx> wrote: > >> of_irq_parse_one() does a get() on the device node returned in out_irq->np. > >> Callers of of_irq_parse_one() must do a put() when they are done with it. > > > > What does "be done with it" really mean here? > > > >> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@xxxxxxxxxxxxxxx> > > > >> --- a/arch/arm/mach-shmobile/regulator-quirk-rcar-gen2.c > >> +++ b/arch/arm/mach-shmobile/regulator-quirk-rcar-gen2.c > >> @@ -184,6 +184,7 @@ static int __init rcar_gen2_regulator_quirk(void) > >> kfree(quirk); > >> continue; > >> } > >> + of_node_put(argsa->np); > > > > The quirk object, which is a container of argsa, is still used below, > > and stored in a linked list. I agree argsa->np is not dereferenced, > > but the pointer itself is still compared to other pointers. > > I fail to see when the pointers are compared. It looks to me that only > the args are compared. Am I missing something ? You're right, in upstream, there is no such check. In my local tree, I have converted the comparisons below to use a new helper of_phandle_args_eq() (which does compare the np member, too), but that change never went upstream, as the other user of that helper was rejected. > In any case, looking more closely at the code, I guess that indeed the > of_node_put() shouldn't be added here because this code expects that the > nodes never go away. That is probably a good assertion in case of PMICs OK. > > IIUIC, calling of_node_put() might cause the reference count to drop to > > zero, and the underlying struct node object to be deallocated. > > So when a future reference to the same DT node will be taken, a new > > struct node object will be allocated, and the pointer comparison below > > will fail? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds