On Wed, Jul 29, 2015 at 09:19:22AM +0200, Vlastimil Babka wrote:
> How would one define a static key that's e.g. expected to be mostly false, but
> with initial value of true, e.g. during boot?
DEFINE_STATIC_KEY_TRUE(blah);
will get you the true at boot time.
You'll then want to use:
if (static_branch_unlikely(&blah)) {
/* code that mostly doesn't happen */
}
To indicate you expect it to be false most of the time. And you'll flip
it to false at runtime using:
static_branch_disable(&blah);
If GCC co-operates, the body of the branch will be placed out-of-line,
we'll emit a jump to it by default, but once you disable it, we'll nop
the jump and fall straight through.
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