maps/ringbuf: make RingBuf: Send + Sync

There was no reason for them not to be -- the APIs all require mutable
references and hold onto mutable references, so there cannot be internal
concurrency. The !Send + !Sync came from the MMap, but not for any good
reason.

aya/src/maps/ring_buf.rs

@@ -412,6 +412,11 @@ struct MMap {
     len: usize,
 }
 
+// Needed because NonNull<T> is !Send and !Sync out of caution that the data
+// might be aliased unsafely.
+unsafe impl Send for MMap {}
+unsafe impl Sync for MMap {}
+
 impl MMap {
     fn new(
         fd: BorrowedFd<'_>,

xtask/public-api/aya.txt

@@ -589,8 +589,8 @@ pub type aya::maps::ring_buf::RingBuf<&'a mut aya::maps::MapData>::Error = aya::
 pub fn aya::maps::ring_buf::RingBuf<&'a mut aya::maps::MapData>::try_from(map: &'a mut aya::maps::Map) -> core::result::Result<Self, Self::Error>
 impl<T: core::borrow::Borrow<aya::maps::MapData>> std::os::fd::raw::AsRawFd for aya::maps::ring_buf::RingBuf<T>
 pub fn aya::maps::ring_buf::RingBuf<T>::as_raw_fd(&self) -> std::os::fd::raw::RawFd
-impl<T> !core::marker::Send for aya::maps::ring_buf::RingBuf<T>
-impl<T> !core::marker::Sync for aya::maps::ring_buf::RingBuf<T>
+impl<T> core::marker::Send for aya::maps::ring_buf::RingBuf<T> where T: core::marker::Send
+impl<T> core::marker::Sync for aya::maps::ring_buf::RingBuf<T> where T: core::marker::Sync
 impl<T> core::marker::Unpin for aya::maps::ring_buf::RingBuf<T> where T: core::marker::Unpin
 impl<T> core::panic::unwind_safe::RefUnwindSafe for aya::maps::ring_buf::RingBuf<T> where T: core::panic::unwind_safe::RefUnwindSafe
 impl<T> core::panic::unwind_safe::UnwindSafe for aya::maps::ring_buf::RingBuf<T> where T: core::panic::unwind_safe::UnwindSafe
@@ -618,8 +618,8 @@ pub type aya::maps::ring_buf::RingBufItem<'_>::Target = [u8]
 pub fn aya::maps::ring_buf::RingBufItem<'_>::deref(&self) -> &Self::Target
 impl core::ops::drop::Drop for aya::maps::ring_buf::RingBufItem<'_>
 pub fn aya::maps::ring_buf::RingBufItem<'_>::drop(&mut self)
-impl<'a> !core::marker::Send for aya::maps::ring_buf::RingBufItem<'a>
-impl<'a> !core::marker::Sync for aya::maps::ring_buf::RingBufItem<'a>
+impl<'a> core::marker::Send for aya::maps::ring_buf::RingBufItem<'a>
+impl<'a> core::marker::Sync for aya::maps::ring_buf::RingBufItem<'a>
 impl<'a> core::marker::Unpin for aya::maps::ring_buf::RingBufItem<'a>
 impl<'a> core::panic::unwind_safe::RefUnwindSafe for aya::maps::ring_buf::RingBufItem<'a>
 impl<'a> !core::panic::unwind_safe::UnwindSafe for aya::maps::ring_buf::RingBufItem<'a>
@@ -2077,8 +2077,8 @@ pub type aya::maps::ring_buf::RingBuf<&'a mut aya::maps::MapData>::Error = aya::
 pub fn aya::maps::ring_buf::RingBuf<&'a mut aya::maps::MapData>::try_from(map: &'a mut aya::maps::Map) -> core::result::Result<Self, Self::Error>
 impl<T: core::borrow::Borrow<aya::maps::MapData>> std::os::fd::raw::AsRawFd for aya::maps::ring_buf::RingBuf<T>
 pub fn aya::maps::ring_buf::RingBuf<T>::as_raw_fd(&self) -> std::os::fd::raw::RawFd
-impl<T> !core::marker::Send for aya::maps::ring_buf::RingBuf<T>
-impl<T> !core::marker::Sync for aya::maps::ring_buf::RingBuf<T>
+impl<T> core::marker::Send for aya::maps::ring_buf::RingBuf<T> where T: core::marker::Send
+impl<T> core::marker::Sync for aya::maps::ring_buf::RingBuf<T> where T: core::marker::Sync
 impl<T> core::marker::Unpin for aya::maps::ring_buf::RingBuf<T> where T: core::marker::Unpin
 impl<T> core::panic::unwind_safe::RefUnwindSafe for aya::maps::ring_buf::RingBuf<T> where T: core::panic::unwind_safe::RefUnwindSafe
 impl<T> core::panic::unwind_safe::UnwindSafe for aya::maps::ring_buf::RingBuf<T> where T: core::panic::unwind_safe::UnwindSafe