On Monday 30 December 2013, zhangfei wrote:

quoted

quoted

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+static int dw_mci_k3_suspend(struct device *dev)
+{
+    struct dw_mci *host = dev_get_drvdata(dev);
+    int ret = 0;
+
+    ret = dw_mci_suspend(host);

You should never initialize local variables when they are set later in the
function (the ret = 0 part above). For more complex functions, this prevents
gcc from warning you about accidentally uninitialized uses.

I am sorry I may fall into the dead end, but still quite not understand 
this rule.
I alwayes thought it would be a good habit to init local variables before.
Do you mean it should NOT init local variable as much as possible and 
only init on demand, like solving the gcc warning.
Why not init the them at start in case random value cause unpredicted error?

The gcc warnings are 100% correct, we can use them as a tool to write better
code. If you write code that has no warnings with a modern compiler, you will
never use random values, but if you always initialize the local variables,
you can end up accidentally using '0' where you shouldn't have.

See http://rusty.ozlabs.org/?p=232 for an excellent article on the topic
by former Linaro assignee Rusty Russell.

	Arnd