quoted

+/**
+ * generic_test_bit - Determine whether a bit is set
+ * @nr: bit number to test
+ * @addr: Address to start counting from
+ */

Shouldn't we add in this or in separate patch a big NOTE to explain that this
is actually atomic and must be kept as a such?

"atomic" isn't really the right word. The volatile access makes sure that the
compiler does the test at the point that the source code asked, and doesn't
move it before/after other operations.

But there is no such thing as an atomic test_bit() operation:

	if (test_bit(5, addr)) {
		/* some other CPU nukes bit 5 */

		/* I know it was set when I looked, but now, could be anything */

		...
	}

-Tony