#define SHARED_EDIT     \
    STMT_START {        \
        ENTER_LOCK;     \
        SHARED_CONTEXT; \
    } STMT_END

/* ... then switch out and release access. */
#define SHARED_RELEASE  \
    STMT_START {        \
        CALLER_CONTEXT; \
        LEAVE_LOCK;     \
    } STMT_END