This is a note to let you know that I've just added the patch titled
SUNRPC: Use RMW bitops in single-threaded hot paths
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sunrpc-use-rmw-bitops-in-single-threaded-hot-paths.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 79142ce544623416ef73208a53eb962c7d25565c
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date: Fri Apr 29 10:06:21 2022 -0400
SUNRPC: Use RMW bitops in single-threaded hot paths
[ Upstream commit 28df0988815f63e2af5e6718193c9f68681ad7ff ]
I noticed CPU pipeline stalls while using perf.
Once an svc thread is scheduled and executing an RPC, no other
processes will touch svc_rqst::rq_flags. Thus bus-locked atomics are
not needed outside the svc thread scheduler.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 3ac2978c596ae..5b56877c7fb57 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -970,7 +970,7 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
* the client wants us to do more in this compound:
*/
if (!nfsd4_last_compound_op(rqstp))
- clear_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
+ __clear_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
/* check stateid */
status = nfs4_preprocess_stateid_op(rqstp, cstate, &cstate->current_fh,
@@ -2644,11 +2644,12 @@ nfsd4_proc_compound(struct svc_rqst *rqstp)
cstate->minorversion = args->minorversion;
fh_init(current_fh, NFS4_FHSIZE);
fh_init(save_fh, NFS4_FHSIZE);
+
/*
* Don't use the deferral mechanism for NFSv4; compounds make it
* too hard to avoid non-idempotency problems.
*/
- clear_bit(RQ_USEDEFERRAL, &rqstp->rq_flags);
+ __clear_bit(RQ_USEDEFERRAL, &rqstp->rq_flags);
/*
* According to RFC3010, this takes precedence over all other errors.
@@ -2770,7 +2771,7 @@ nfsd4_proc_compound(struct svc_rqst *rqstp)
out:
cstate->status = status;
/* Reset deferral mechanism for RPC deferrals */
- set_bit(RQ_USEDEFERRAL, &rqstp->rq_flags);
+ __set_bit(RQ_USEDEFERRAL, &rqstp->rq_flags);
return rpc_success;
}
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 771d3057577ef..96d41b1cc2d17 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2408,7 +2408,7 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
argp->rqstp->rq_cachetype = cachethis ? RC_REPLBUFF : RC_NOCACHE;
if (readcount > 1 || max_reply > PAGE_SIZE - auth_slack)
- clear_bit(RQ_SPLICE_OK, &argp->rqstp->rq_flags);
+ __clear_bit(RQ_SPLICE_OK, &argp->rqstp->rq_flags);
return true;
}
diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 48b608cb5f5ec..2381c5d1b0710 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -900,7 +900,7 @@ unwrap_integ_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct g
* rejecting the server-computed MIC in this somewhat rare case,
* do not use splice with the GSS integrity service.
*/
- clear_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
+ __clear_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
/* Did we already verify the signature on the original pass through? */
if (rqstp->rq_deferred)
@@ -972,7 +972,7 @@ unwrap_priv_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct gs
int pad, remaining_len, offset;
u32 rseqno;
- clear_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
+ __clear_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
priv_len = svc_getnl(&buf->head[0]);
if (rqstp->rq_deferred) {
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 87da3ff46ce9a..f2a8c1ee8530e 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -1281,10 +1281,10 @@ svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
goto err_short_len;
/* Will be turned off by GSS integrity and privacy services */
- set_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
+ __set_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
/* Will be turned off only when NFSv4 Sessions are used */
- set_bit(RQ_USEDEFERRAL, &rqstp->rq_flags);
- clear_bit(RQ_DROPME, &rqstp->rq_flags);
+ __set_bit(RQ_USEDEFERRAL, &rqstp->rq_flags);
+ __clear_bit(RQ_DROPME, &rqstp->rq_flags);
svc_putu32(resv, rqstp->rq_xid);
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 67ccf1a6459ae..39acef5134f5c 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -1251,7 +1251,7 @@ static struct cache_deferred_req *svc_defer(struct cache_req *req)
trace_svc_defer(rqstp);
svc_xprt_get(rqstp->rq_xprt);
dr->xprt = rqstp->rq_xprt;
- set_bit(RQ_DROPME, &rqstp->rq_flags);
+ __set_bit(RQ_DROPME, &rqstp->rq_flags);
dr->handle.revisit = svc_revisit;
return &dr->handle;
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index be7081284a098..46cea0e413aeb 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -298,9 +298,9 @@ static void svc_sock_setbufsize(struct svc_sock *svsk, unsigned int nreqs)
static void svc_sock_secure_port(struct svc_rqst *rqstp)
{
if (svc_port_is_privileged(svc_addr(rqstp)))
- set_bit(RQ_SECURE, &rqstp->rq_flags);
+ __set_bit(RQ_SECURE, &rqstp->rq_flags);
else
- clear_bit(RQ_SECURE, &rqstp->rq_flags);
+ __clear_bit(RQ_SECURE, &rqstp->rq_flags);
}
/*
@@ -1005,9 +1005,9 @@ static int svc_tcp_recvfrom(struct svc_rqst *rqstp)
rqstp->rq_xprt_ctxt = NULL;
rqstp->rq_prot = IPPROTO_TCP;
if (test_bit(XPT_LOCAL, &svsk->sk_xprt.xpt_flags))
- set_bit(RQ_LOCAL, &rqstp->rq_flags);
+ __set_bit(RQ_LOCAL, &rqstp->rq_flags);
else
- clear_bit(RQ_LOCAL, &rqstp->rq_flags);
+ __clear_bit(RQ_LOCAL, &rqstp->rq_flags);
p = (__be32 *)rqstp->rq_arg.head[0].iov_base;
calldir = p[1];
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index f776f0cb471f0..ac147304fb0e9 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -602,7 +602,7 @@ static int svc_rdma_has_wspace(struct svc_xprt *xprt)
static void svc_rdma_secure_port(struct svc_rqst *rqstp)
{
- set_bit(RQ_SECURE, &rqstp->rq_flags);
+ __set_bit(RQ_SECURE, &rqstp->rq_flags);
}
static void svc_rdma_kill_temp_xprt(struct svc_xprt *xprt)
