The netmap_ring struct starts with various const members and rencent
clang warns about leaving them uninitialized. Having them const in the
first place is highly suspicious since they are updated with various
macros but using hand-coded __DECONST(). But fixing that is a more
invasive change that I am unable to test.
```
.../freebsd/sys/dev/netmap/netmap_kloop.c:320:21: error: default initialization of an object of type 'struct netmap_ring' with const member leaves the object uninitialized [-Werror,-Wdefault-const-init-field-unsafe]
320 | struct netmap_ring shadow_ring; /* shadow copy of the netmap_ring */
| ^
.../freebsd/sys/net/netmap.h:290:16: note: member 'buf_ofs' declared 'const' here
290 | const int64_t buf_ofs;
| ^
```
Test Plan: Compiles
Reviewed by: vmaffione, jhb
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D52568
(cherry picked from commit 2ed21f90906b230476d3f12ff9dce0e2c4642af2)
Add SYNC_KLOOP_MODE option, and add support for direct mode, where application
executes the TXSYNC and RXSYNC in the context of the ioeventfd wake up callback.
MFC after: 5 days
On sync-kloop stop, send a wake-up signal to the kloop, so that
waiting for the timeout is not needed.
Also, improve logging in netmap_freebsd.c.
MFC after: 3 days
Changelist:
- Add the proper memory barriers in the kloop ring processing
functions.
- Fix memory barriers usage in the user helpers (nm_sync_kloop_appl_write,
nm_sync_kloop_appl_read).
- Fix nm_kr_txempty() helper to look at rhead rather than rcur. This
is important since the kloop can read a value of rcur which is ahead
of the value of rhead (see explanation in nm_sync_kloop_appl_write)
- Remove obsolete ptnetmap_guest_write_kring_csb() and
ptnet_guest_read_kring_csb(), and update if_ptnet(4) to use those.
- Prepare in advance the arguments for netmap_sync_kloop_[tr]x_ring(),
to make the kloop faster.
- Provide kernel and user implementation for nm_ldld_barrier() and
nm_ldst_barrier()
MFC after: 2 weeks
Changelist:
- Replace netmap passthrough host support with a more general
mechanism to call TXSYNC/RXSYNC from an in-kernel event-loop.
No kernel threads are used to use this feature: the application
is required to spawn a thread (or a process) and issue a
SYNC_KLOOP_START (NIOCCTRL) command in the thread body. The
kernel loop is executed by the ioctl implementation, which returns
to userspace only when a different thread calls SYNC_KLOOP_STOP
or the netmap file descriptor is closed.
- Update the if_ptnet driver to cope with the new data structures,
and prune all the obsolete ptnetmap code.
- Add support for "null" netmap ports, useful to allocate netmap_if,
netmap_ring and netmap buffers to be used by specialized applications
(e.g. hypervisors). TXSYNC/RXSYNC on these ports have no effect.
- Various fixes and code refactoring.
Sponsored by: Sunny Valley Networks
Differential Revision: https://reviews.freebsd.org/D18015
