SUNRPC: always free ctxt when freeing deferred request

Since the ->xprt_ctxt pointer was added to svc_deferred_req, it has not
been sufficient to use kfree() to free a deferred request.  We may need
to free the ctxt as well.

As freeing the ctxt is all that ->xpo_release_rqst() does, we repurpose
it to explicit do that even when the ctxt is not stored in an rqst.
So we now have ->xpo_release_ctxt() which is given an xprt and a ctxt,
which may have been taken either from an rqst or from a dreq.  The
caller is now responsible for clearing that pointer after the call to
->xpo_release_ctxt.

We also clear dr->xprt_ctxt when the ctxt is moved into a new rqst when
revisiting a deferred request.  This ensures there is only one pointer
to the ctxt, so the risk of double freeing in future is reduced.  The
new code in svc_xprt_release which releases both the ctxt and any
rq_deferred depends on this.

Fixes: 773f91b2cf3f ("SUNRPC: Fix NFSD's request deferral on RDMA transports")
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index 867479204840..a6b12631db21 100644
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -23,7 +23,7 @@ struct svc_xprt_ops {
 	int		(*xpo_sendto)(struct svc_rqst *);
 	int		(*xpo_result_payload)(struct svc_rqst *, unsigned int,
 					      unsigned int);
-	void		(*xpo_release_rqst)(struct svc_rqst *);
+	void		(*xpo_release_ctxt)(struct svc_xprt *xprt, void *ctxt);
 	void		(*xpo_detach)(struct svc_xprt *);
 	void		(*xpo_free)(struct svc_xprt *);
 	void		(*xpo_kill_temp_xprt)(struct svc_xprt *);