In order to avoid blocking a service thread, the receive side checks
to see if there is sufficient write space to reply to the request.
Each transport has a different mechanism for determining if there is
enough write space to reply.
The code that checked for white space was coupled with code that
checked for CLOSE and CONN. These checks have been broken out into
separate statements to make the code easier to read.
Signed-off-by: Tom Tucker <[email protected]>
---
include/linux/sunrpc/svc_xprt.h | 1 +
net/sunrpc/svcsock.c | 60 +++++++++++++++++++++++++++++++++------
2 files changed, 51 insertions(+), 10 deletions(-)
diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index 8501115..3adc8f3 100644
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -10,6 +10,7 @@
#include <linux/sunrpc/svc.h>
struct svc_xprt_ops {
+ int (*xpo_has_wspace)(struct svc_xprt *);
int (*xpo_recvfrom)(struct svc_rqst *);
void (*xpo_prep_reply_hdr)(struct svc_rqst *);
int (*xpo_sendto)(struct svc_rqst *);
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 510ad45..b796244 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -269,22 +269,24 @@ svc_sock_enqueue(struct svc_sock *svsk)
BUG_ON(svsk->sk_pool != NULL);
svsk->sk_pool = pool;
- set_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);
- if (((atomic_read(&svsk->sk_reserved) + serv->sv_max_mesg)*2
- > svc_sock_wspace(svsk))
- && !test_bit(SK_CLOSE, &svsk->sk_flags)
- && !test_bit(SK_CONN, &svsk->sk_flags)) {
+ /* Handle pending connection */
+ if (test_bit(SK_CONN, &svsk->sk_flags))
+ goto process;
+
+ /* Handle close in-progress */
+ if (test_bit(SK_CLOSE, &svsk->sk_flags))
+ goto process;
+
+ /* Check if we have space to reply to a request */
+ if (!svsk->sk_xprt.xpt_ops->xpo_has_wspace(&svsk->sk_xprt)) {
/* Don't enqueue while not enough space for reply */
- dprintk("svc: socket %p no space, %d*2 > %ld, not enqueued\n",
- svsk->sk_sk, atomic_read(&svsk->sk_reserved)+serv->sv_max_mesg,
- svc_sock_wspace(svsk));
+ dprintk("svc: no write space, socket %p not enqueued\n", svsk);
svsk->sk_pool = NULL;
clear_bit(SK_BUSY, &svsk->sk_flags);
goto out_unlock;
}
- clear_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);
-
+ process:
if (!list_empty(&pool->sp_threads)) {
rqstp = list_entry(pool->sp_threads.next,
struct svc_rqst,
@@ -897,6 +899,24 @@ static void svc_udp_prep_reply_hdr(struct svc_rqst *rqstp)
{
}
+static int svc_udp_has_wspace(struct svc_xprt *xprt)
+{
+ struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
+ struct svc_serv *serv = svsk->sk_server;
+ int required;
+
+ /*
+ * Set the SOCK_NOSPACE flag before checking the available
+ * sock space.
+ */
+ set_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);
+ required = atomic_read(&svsk->sk_reserved) + serv->sv_max_mesg;
+ if (required*2 > sock_wspace(svsk->sk_sk))
+ return 0;
+ clear_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);
+ return 1;
+}
+
static struct svc_xprt_ops svc_udp_ops = {
.xpo_recvfrom = svc_udp_recvfrom,
.xpo_sendto = svc_udp_sendto,
@@ -904,6 +924,7 @@ static struct svc_xprt_ops svc_udp_ops = {
.xpo_detach = svc_sock_detach,
.xpo_free = svc_sock_free,
.xpo_prep_reply_hdr = svc_udp_prep_reply_hdr,
+ .xpo_has_wspace = svc_udp_has_wspace,
};
static struct svc_xprt_class svc_udp_class = {
@@ -1366,6 +1387,24 @@ static void svc_tcp_prep_reply_hdr(struct svc_rqst *rqstp)
svc_putnl(resv, 0);
}
+static int svc_tcp_has_wspace(struct svc_xprt *xprt)
+{
+ struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
+ struct svc_serv *serv = svsk->sk_server;
+ int required;
+
+ /*
+ * Set the SOCK_NOSPACE flag before checking the available
+ * sock space.
+ */
+ set_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);
+ required = atomic_read(&svsk->sk_reserved) + serv->sv_max_mesg;
+ if (required*2 > sk_stream_wspace(svsk->sk_sk))
+ return 0;
+ clear_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);
+ return 1;
+}
+
static struct svc_xprt_ops svc_tcp_ops = {
.xpo_recvfrom = svc_tcp_recvfrom,
.xpo_sendto = svc_tcp_sendto,
@@ -1373,6 +1412,7 @@ static struct svc_xprt_ops svc_tcp_ops = {
.xpo_detach = svc_sock_detach,
.xpo_free = svc_sock_free,
.xpo_prep_reply_hdr = svc_tcp_prep_reply_hdr,
+ .xpo_has_wspace = svc_tcp_has_wspace,
};
static struct svc_xprt_class svc_tcp_class = {