linux.git/include/linux/sunrpc/xprt.h, branch v7.1

xprtrdma: Close lost-wakeup race in xprt_rdma_alloc_slot

2026-04-13T18:56:20+00:00

xprt_rdma_alloc_slot() and xprt_rdma_free_slot() lack serialization
between the buffer pool and the backlog queue.  A buffer freed
after rpcrdma_buffer_get() finds the pool empty but before
rpc_sleep_on() places the task on the backlog is returned to the
pool with no waiter to wake, leaving the task stuck on the backlog
indefinitely.

After joining the backlog, re-check the pool and route any
recovered buffer through xprt_wake_up_backlog(), whose queue lock
serializes with concurrent wakeups and avoids double-assignment
of slots.

Because xprt_rdma_free_slot() does not hold reserve_lock, the
XPRT_CONGESTED double-check in xprt_throttle_congested() is
ineffective: a task can join the backlog through that path after
free_slot has already found it empty and cleared the bit.  Avoid
this by using xprt_add_backlog_noncongested(), which queues the
task without setting XPRT_CONGESTED, so every allocation reaches
xprt_rdma_alloc_slot() and its post-sleep re-check.

Fixes: edb41e61a54e ("xprtrdma: Make rpc_rqst part of rpcrdma_req")
Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust

sunrpc: implement rfc2203 rpcsec_gss seqnum cache

2025-05-19T14:14:29+00:00

This implements a sequence number cache of the last three (right now
hardcoded) sent sequence numbers for a given XID, as suggested by the
RFC.

From RFC2203 5.3.3.1:

"Note that the sequence number algorithm requires that the client
increment the sequence number even if it is retrying a request with
the same RPC transaction identifier.  It is not infrequent for
clients to get into a situation where they send two or more attempts
and a slow server sends the reply for the first attempt. With
RPCSEC_GSS, each request and reply will have a unique sequence
number. If the client wishes to improve turn around time on the RPC
call, it can cache the RPCSEC_GSS sequence number of each request it
sends. Then when it receives a response with a matching RPC
transaction identifier, it can compute the checksum of each sequence
number in the cache to try to match the checksum in the reply's
verifier."

Signed-off-by: Nikhil Jha 
Acked-by: Chuck Lever 
Signed-off-by: Anna Schumaker

SUNRPC: Add a transport callback to handle dequeuing of an RPC request

2024-02-28T20:00:14+00:00

Add a transport level callback to allow it to handle the consequences of
dequeuing the request that was in the process of being transmitted.
For something like a TCP connection, we may need to disconnect if the
request was partially transmitted.

Signed-off-by: Trond Myklebust

NFSv4.1: Use the nfs_client's rpc timeouts for backchannel

2024-01-04T22:01:01+00:00

For backchannel requests that lookup the appropriate nfs_client, use the
state-management rpc_clnt's rpc_timeout parameters for the backchannel's
response.  When the nfs_client cannot be found, fall back to using the
xprt's default timeout parameters.

Signed-off-by: Benjamin Coddington 
Tested-by: Chuck Lever 
Tested-by: Jeff Layton 
Signed-off-by: Anna Schumaker

SUNRPC: change the back-channel queue to lwq

2023-10-16T16:44:08+00:00

This removes the need to store and update back-links in the list.
It also remove the need for the _bh version of spin_lock().

Signed-off-by: NeilBrown 
Cc: Trond Myklebust 
Cc: Anna Schumaker 
Signed-off-by: Chuck Lever

SUNRPC: Allow specification of TCP client connect timeout at setup

2023-08-24T17:24:15+00:00

When we create a TCP transport, the connect timeout parameters are
currently fixed to be 90s. This is problematic in the pNFS flexfiles
case, where we may have multiple mirrors, and we would like to fail over
quickly to the next mirror if a data server is down.

This patch adds the ability to specify the connection parameters at RPC
client creation time.

Signed-off-by: Trond Myklebust 
Signed-off-by: Anna Schumaker

SUNRPC: Add a TCP-with-TLS RPC transport class

2023-06-19T16:28:10+00:00

Use the new TLS handshake API to enable the SunRPC client code
to request a TLS handshake. This implements support for RFC 9289,
only on TCP sockets.

Upper layers such as NFS use RPC-with-TLS to protect in-transit
traffic.

Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust

SUNRPC: Plumb an API for setting transport layer security

2023-06-19T16:16:59+00:00

Add an initial set of policies along with fields for upper layers to
pass the requested policy down to the transport layer.

Signed-off-by: Chuck Lever 
Reviewed-by: Jeff Layton 
Signed-off-by: Trond Myklebust

SUNRPC: Don't reuse bvec on retransmission of the request

2022-07-27T20:26:17+00:00

If a request is re-encoded and then retransmitted, we need to make sure
that we also re-encode the bvec, in case the page lists have changed.

Fixes: ff053dbbaffe ("SUNRPC: Move the call to xprt_send_pagedata() out of xprt_sock_sendmsg()")
Signed-off-by: Trond Myklebust

SUNRPC expose functions for offline remote xprt functionality

2022-07-25T14:06:04+00:00

Re-arrange the code that make offline transport and delete transport
callable functions.

Signed-off-by: Olga Kornievskaia 
Signed-off-by: Trond Myklebust