On Fri, 2023-01-06 at 12:43 -0500, Chuck Lever wrote:

From: Chuck Lever <redacted>

The premise that "Once an svc thread is scheduled and executing an
RPC, no other processes will touch svc_rqst::rq_flags" is false.
svc_xprt_enqueue() examines the RQ_BUSY flag in scheduled nfsd
threads when determining which thread to wake up next.

Found via KCSAN.

Fixes: 28df0988815f ("SUNRPC: Use RMW bitops in single-threaded hot paths")
Signed-off-by: Chuck Lever <redacted>
---
 fs/nfsd/nfs4proc.c                       |    7 +++----
 fs/nfsd/nfs4xdr.c                        |    2 +-
 net/sunrpc/auth_gss/svcauth_gss.c        |    4 ++--
 net/sunrpc/svc.c                         |    6 +++---
 net/sunrpc/svc_xprt.c                    |    2 +-
 net/sunrpc/svcsock.c                     |    8 ++++----
 net/sunrpc/xprtrdma/svc_rdma_transport.c |    2 +-
 7 files changed, 15 insertions(+), 16 deletions(-)

Makes sense.

Reviewed-by: Jeff Layton <jlayton@kernel.org>