On 09/02/2016 04:36 AM, Masahiro Yamada wrote:
-ret = expression; -if (ret)
return ret;-return 0; +return expression;
I disagree with this change if applied blindly; I think both coding styles have their merit depending on the semantic context.
In the case of a simple wrapper function that just calls another with different arguments, directly returning the result from the called function make sense. For example:
int device_bind(struct udevice *parent, const struct driver *drv, const char *name, void *platdata, int of_offset, struct udevice **devp) { return device_bind_common(parent, drv, name, platdata, 0, of_offset, 0, devp); }
However, where the top-level function is more complex, especially where it calls multiple functions in its body, I think it's best to use the exact same style to call all functions in the top-level body, and just "return 0" separately at the end. For example:
static int tegra186_bpmp_bind(struct udevice *dev) { int ret; struct udevice *child;
debug("%s(dev=%p)\n", __func__, dev); ret = device_bind_driver_to_node(dev, "tegra186_clk", "tegra186_clk", dev->of_offset, &child); if (ret) return ret; ret = device_bind_driver_to_node(dev, "tegra186_reset", "tegra186_reset", dev->of_offset, &child); if (ret) return ret; ret = device_bind_driver_to_node(dev, "tegra186_power_domain", "tegra186_power_domain", dev->of_offset, &child); if (ret) return ret; ret = dm_scan_fdt_dev(dev); if (ret) return ret; return 0;}
All child function calls are structured the same, so someone reading the code will always see the same structure irrespective of where in a function a child function is called. This gives uniformity. This also yields a few maintenance advantages below, and helps keep all code uniform even if any of the maintenance operations below have been applied to some functions and aren't needed in others.
1)
If tegra186_bpmp_bind() were modified to call an additional function in its body, the diff for that addition would look identical no matter whether the new call was added at the start/middle/end of the body. We wouldn't ever have to do something like:
- return dm_scan_fdt_dev(dev); + ret = dm_scan_fdt_dev(dev); + if (ret) + return ret;
... which is an edit to a piece of code that's unrelated to the code being added, and thus makes the patch more confusing.
2)
There's always an obvious place to put any debug()/error() invocations, or translate return values; inside the if (ret) body. There's only one way for the code to look so it doesn't change based on what exactly we do with the return value.
3)
If we add the need for cleanup logic in the failure case, we can just blindly change "return ret" to "goto fail" without re-structuring code.