smb: smbdirect: introduce smbdirect_socket.recv_io.credits.available

The logic off managing recv credits by counting posted recv_io and
granted credits is racy.

That's because the peer might already consumed a credit,
but between receiving the incoming recv at the hardware
and processing the completion in the 'recv_done' functions
we likely have a window where we grant credits, which
don't really exist.

So we better have a decicated counter for the
available credits, which will be incremented
when we posted new recv buffers and drained when
we grant the credits to the peer.

Fixes: 5fb9b459b368 ("smb: client: count the number of posted recv_io messages in order to calculated credits")
Fixes: 89b021a72663 ("smb: server: manage recv credits by counting posted recv_io and granted credits")
Cc: <stable@vger.kernel.org> # 6.18.x
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/common/smbdirect/smbdirect_socket.h b/fs/smb/common/smbdirect/smbdirect_socket.h
index ee4c2726771a34775f972ffcbbb69891900dcbdf..403a8b2cd30e4ac096880169a5a9b5862d030cab 100644 (file)
--- a/fs/smb/common/smbdirect/smbdirect_socket.h
+++ b/fs/smb/common/smbdirect/smbdirect_socket.h
@@ -239,6 +239,7 @@ struct smbdirect_socket {
                 */
                struct {
                        u16 target;
+                       atomic_t available;
                        atomic_t count;
                } credits;
 
@@ -387,6 +388,7 @@ static __always_inline void smbdirect_socket_init(struct smbdirect_socket *sc)
        INIT_WORK(&sc->recv_io.posted.refill_work, __smbdirect_socket_disabled_work);
        disable_work_sync(&sc->recv_io.posted.refill_work);
 
+       atomic_set(&sc->recv_io.credits.available, 0);
        atomic_set(&sc->recv_io.credits.count, 0);
 
        INIT_LIST_HEAD(&sc->recv_io.reassembly.list);