On Wed, Jul 29, 2015 at 07:50:24PM +0200, Dr. H. Nikolaus Schaller wrote: > > Am 29.07.2015 um 19:26 schrieb Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>: > > > On Tue, Jul 28, 2015 at 10:13:54PM -0500, Rob Herring wrote: > >> On Tue, Jul 28, 2015 at 3:23 PM, Belisko Marek <marek.belisko@xxxxxxxxx> wrote: > >>> Hi Dmitry, > >>> > >>> On Thu, Jul 23, 2015 at 10:53 PM, Dmitry Torokhov > >>> <dmitry.torokhov@xxxxxxxxx> wrote: > >>>> On Thu, Jul 23, 2015 at 10:38:34PM +0200, Marek Belisko wrote: > >>>>> Fix following: > >>>>> [ 8.862274] ERROR: Bad of_node_put() on /ocp/i2c@48070000/twl@48/audio > >>>>> [ 8.869293] CPU: 0 PID: 1003 Comm: modprobe Not tainted 4.2.0-rc2-letux+ #1175 > >>>>> [ 8.876922] Hardware name: Generic OMAP36xx (Flattened Device Tree) > >>>>> [ 8.883514] [<c00159e0>] (unwind_backtrace) from [<c0012488>] (show_stack+0x10/0x14) > >>>>> [ 8.891693] [<c0012488>] (show_stack) from [<c05cb810>] (dump_stack+0x78/0x94) > >>>>> [ 8.899322] [<c05cb810>] (dump_stack) from [<c02cfd5c>] (kobject_release+0x68/0x7c) > >>>>> [ 8.907409] [<c02cfd5c>] (kobject_release) from [<bf0040c4>] (twl4030_vibra_probe+0x74/0x188 [twl4030_vibra]) > >>>>> [ 8.917877] [<bf0040c4>] (twl4030_vibra_probe [twl4030_vibra]) from [<c03816ac>] (platform_drv_probe+0x48/0x90) > >>>>> [ 8.928497] [<c03816ac>] (platform_drv_probe) from [<c037feb4>] (really_probe+0xd4/0x238) > >>>>> [ 8.937103] [<c037feb4>] (really_probe) from [<c0380160>] (driver_probe_device+0x30/0x48) > >>>>> [ 8.945678] [<c0380160>] (driver_probe_device) from [<c03801e0>] (__driver_attach+0x68/0x8c) > >>>>> [ 8.954589] [<c03801e0>] (__driver_attach) from [<c037ea60>] (bus_for_each_dev+0x50/0x84) > >>>>> [ 8.963226] [<c037ea60>] (bus_for_each_dev) from [<c037f828>] (bus_add_driver+0xcc/0x1e4) > >>>>> [ 8.971832] [<c037f828>] (bus_add_driver) from [<c0380b60>] (driver_register+0x9c/0xe0) > >>>>> [ 8.980255] [<c0380b60>] (driver_register) from [<c00097e0>] (do_one_initcall+0x100/0x1b8) > >>>>> [ 8.988983] [<c00097e0>] (do_one_initcall) from [<c00b8008>] (do_init_module+0x58/0x1c0) > >>>>> [ 8.997497] [<c00b8008>] (do_init_module) from [<c00b8cac>] (SyS_init_module+0x54/0x64) > >>>>> [ 9.005950] [<c00b8cac>] (SyS_init_module) from [<c000ed20>] (ret_fast_syscall+0x0/0x54) > >>>>> [ 9.015838] input: twl4030:vibrator as /devices/platform/68000000.ocp/48070000.i2c/i2c-0/0-0048/48070000.i2c:twl@48:audio/input/input2 > >>>>> > >>>>> node passed to of_find_node_by_name is put inside that function and new node > >>>>> is returned if found. Free returned node not already freed node. > >>>> > >>>> Hmm, if of_find_node_by_name() "puts" passed in node should we not "get" > >>>> it before calling of_find_node_by_name()? The node pointer in question > >>>> is simply copied from parent device. > >>> I'm not sure. what I can say is that I cannot see such error in 4.1 > >>> but only in 4.2-rcx. > >>> Adding Grant and Rob to CC, maybe they know what should be done and > >>> why I see such error in 4.2-rcx. > >> > >> The problem was that node passed into of_find_node_by_name is the the > >> starting point to search, but you should be doing the put on the > >> returned node. So the patch below is correct. > >> > >> As far as why in 4.2, it seems you have OF_DYNAMIC enabled in your > >> config either because you have DT unit test or overlays enabled. > >> Overlays are now user enable-able in 4.2. > > > > Right, but the question was whether we should also "get" the node that > > we are passing into of_find_node_by_name(), or, maybe better, stop > > of_find_node_by_name() from "putting" the node that is passed in? It is > > really surprising behavior. > > I agree that it is quite unexpected and would be much easier to understand > if it would not put the node. > > But I guess it is intended to be a convenience to make it easier to walk down > the tree, i.e. that you can simply write > > np = of_find_node_by_name(NULL, “level11”); > np = of_find_node_by_name(np, “level2”); > np = of_find_node_by_name(np, “level3”); Right, also for_each_node_by_name() relies on this behavior (but we can fix it to use something like __of_find_node_by_name_and_put_from()). > > Otherwise it would need some temporary variable and explicit calls to put the > parent level after finding a child node. > > On the other hand greping for of_find_node_by_name returns many more > calls with parent = NULL than others. So the put is ignored anyways. > > But it is a major change in semantics of a very low level function so it is > easy to introduce regressions (especially in out-of-the tree drivers). I am not sure how much we should care about out of tree drivers; but I worry that there are several callers that simply do: np = of_find_node_by_bame(dev->of_node, "blah"); in our tree... -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
