locking/barriers: Don't use sizeof(void) in lockless_dereference()

My previous commit:

  112dc0c8069e ("locking/barriers: Suppress sparse warnings in lockless_dereference()")

caused sparse to complain that (in radix-tree.h) we use sizeof(void)
since that rcu_dereference()s a void *.

Really, all we need is to have the expression *p in here somewhere
to make sure p is a pointer type, and sizeof(*p) was the thing that
came to my mind first to make sure that's done without really doing
anything at runtime.

Another thing I had considered was using typeof(*p), but obviously
we can't just declare a typeof(*p) variable either, since that may
end up being void. Declaring a variable as typeof(*p)* gets around
that, and still checks that typeof(*p) is valid, so do that. This
type construction can't be done for _________p1 because that will
actually be used and causes sparse address space warnings, so keep
a separate unused variable for it.

Reported-by: Fengguang Wu <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E . McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Fixes: 112dc0c8069e ("locking/barriers: Suppress sparse warnings in lockless_dereference()")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions