On Wed, 18 Nov 2015, Brian Norris wrote: > (changing subject, add devicetree@xxxxxxxxxxxxxxx) > > On Tue, Nov 17, 2015 at 11:33:25PM +0100, Julia Lawall wrote: > > On Tue, 17 Nov 2015, Brian Norris wrote: > > > On Tue, Nov 17, 2015 at 06:48:39PM +0100, Julia Lawall wrote: > > > > Is this something that should be checked for elsewhere? > > > > > > I expect the same sort of problem shows up plenty of other places. I > > > don't think many people use CONFIG_OF_DYNAMIC, so the effects of these > > > failures probably aren't felt by many. > > > > I tried the following semantic patch: > > > > @@ > > struct device_node *e; > > expression e1; > > identifier fld; > > @@ > > > > ... when != of_node_get(...) > > *(<+...e1->fld...+>) = e > > ... when != of_node_get(...) > > return e1; > > > > basically, this says that a structure field is initilized to a device node > > value, the structure is returned by the containing function, and the > > containing function contains no of_node_get at all. Certainly this is > > quite constrained, but it does produce a number of examples. > > > > I looked at a few of them: > > > > drivers/clk/ingenic/cgu.c, ingenic_cgu_new > > clk/pistachio/clk.c, pistachio_clk_alloc_provider > > It looks like the clock core (drivers/clk/clk.c) initially grabs the clk > provider node in of_clk_init(), then drops it after it's initialized, > but most of these providers use of_clk_add_provider(), which seems to > manage the device_node lifetime for the user. So I think these are OK. > > > drivers/mfd/syscon.c, of_syscon_register > > This one looks potentially suspect. Syscon nodes aren't usually directly > managed by a single driver, and the device_node pointer is used for > lookups later...so I think it should keep a kref, and it doesn't. > > > drivers/of/pdt.c, function of_pdt_create_node > > Not real sure about this one. > > > Any idea whether these need of_node_get? In all cases the device node > > value comes in as a parameter. > > I'm really not an expert on this stuff. I just saw a potential problem > that I happen to be looking at in other subsystems, and I wanted to know > what others thought. Thanks for the analysis. I will look into them a bit more. Hopefully at least the maintainer of each file will know what should be done. julia > I think this discussion should include the DT folks > and the subsystems in question. For one, I'm as interested as anyone in > getting this todo clarified: > > Documentation/devicetree/todo.txt > - Document node lifecycle for CONFIG_OF_DYNAMIC > > Regards, > Brian > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
