Drop implementations are not called until the end of a statement. The statement changed in this commit therefore took 4 read locks on a RwLock which can lead to problems if a write lock is requested between any of these read locks. The code looks like it would only hold one lock at a time but it does not drop any of the locks until after the arithmatic operations complete, which leads to this situation. See https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=996079046184329f3a9df1cd19c87da8 to see this in action. The fix is to just take one lock and share it between the three calls to num_presses, letting it drop at the end of the scope.

The issue here is related to that in 9673b8f in that the lock is not dropped when it is expected.  Since the `RwLockReadGuard` produced by `ctx.input()` has a reference taken from it (one into `pointer`), the lock cannot be dropped until that reference is no longre valid, which is the end of the scope (in this case this function).  The following `ctx.input()` then attempts to aquire a second lock on the `RwLock`, creating the same situation that was found in the referenced commit.

This has been resolved by holding one lock on the input for the whole function.