If that is what comes to mind when people talk about white discrimination, then there is a large disconnect in the discussion when talking about the semantic meaning of sexism and racism.
If two people apply to a university and the critical distinction why one got excluded is race, then that is a negative discrimination. If two people are accused of identifical crime and the the critical distinction why one got a harsher sentence is race, then that is negative discrimination. If two people are illegally demonstrating on the street and one get violently assaulted for doing so, and the critical distinction is race, then that is negative discrimination.
Some of that negative discrimination harms white people, some black people, some both in different circumstances, and there is many more situation where such discrimination occurs. Same in regard to gender.