On Fri, 9 Oct 2015, Russell King - ARM Linux wrote: > On Fri, Oct 09, 2015 at 05:14:42PM +0200, Thomas Petazzoni wrote: > > Julia: some of the Device Tree iterator functions have a somewhat > > "interesting" behavior in that they take the reference on the current > > child when entering the loop, and release it before entering the next > > iteration (which will also take a reference to the next child). > > > > This means that if you have an exit point inside the loop (break or > > return), you are loosing a reference. For example, > > http://lxr.free-electrons.com/source/arch/arm/mach-shmobile/pm-rmobile.c#L367 > > is wrong because there is a missing of_node_put(np) before the "return > > -ENOMEM". > > > > So essentially, every exit point in such Device Tree iteration loops > > should make to call of_node_put() on the current element before exiting > > the loop unexpectedly. > > There is an exception to that... if the loop is part of a DT node lookup > function, which would return a DT node based on some search criteria, it > would be valid to break out of the loop while holding a reference. > > For example, of_get_child_by_name(), of_find_next_cache_node(), > of_graph_get_port_by_id(), are valid breaker-outer cases. ;) > > However, of_platform_bus_probe(), of_platform_populate(), > of_overlay_apply_one(), overlay_subtree_check() are examples of > incorrect break-out cases. Thanks for the examples. I guess that this incorrect too, for the opposite reason (double put)? drivers/clk/tegra/clk-emc.c: for_each_child_of_node(np, node) { err = of_property_read_u32(node, "nvidia,ram-code", &node_ram_code); if (err) { of_node_put(node); continue; } julia -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
