[PATCH 1/2] svcrdma: Remove svc_rdma_wq

[PATCH 1/2] svcrdma: Remove svc_rdma_wq

[Chuck Lever]

Clean up: the system workqueue will work just as well.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 include/linux/sunrpc/svc_rdma.h          |    1 -
 net/sunrpc/xprtrdma/svc_rdma.c           |    7 -------
 net/sunrpc/xprtrdma/svc_rdma_transport.c |    3 ++-
 3 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index 981f0d726ad4..edb39900fe04 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -200,7 +200,6 @@ extern struct svc_xprt_class svc_rdma_bc_class;
 #endif
 
 /* svc_rdma.c */
-extern struct workqueue_struct *svc_rdma_wq;
 extern int svc_rdma_init(void);
 extern void svc_rdma_cleanup(void);
 
diff --git a/net/sunrpc/xprtrdma/svc_rdma.c b/net/sunrpc/xprtrdma/svc_rdma.c
index abdb3004a1e3..97bca509a391 100644
--- a/net/sunrpc/xprtrdma/svc_rdma.c
+++ b/net/sunrpc/xprtrdma/svc_rdma.c
@@ -73,8 +73,6 @@ atomic_t rdma_stat_rq_prod;
 atomic_t rdma_stat_sq_poll;
 atomic_t rdma_stat_sq_prod;
 
-struct workqueue_struct *svc_rdma_wq;
-
 /*
  * This function implements reading and resetting an atomic_t stat
  * variable through read/write to a proc file. Any write to the file
@@ -230,7 +228,6 @@ static struct ctl_table svcrdma_root_table[] = {
 void svc_rdma_cleanup(void)
 {
 	dprintk("SVCRDMA Module Removed, deregister RPC RDMA transport\n");
-	destroy_workqueue(svc_rdma_wq);
 	if (svcrdma_table_header) {
 		unregister_sysctl_table(svcrdma_table_header);
 		svcrdma_table_header = NULL;
@@ -246,10 +243,6 @@ int svc_rdma_init(void)
 	dprintk("\tmax_bc_requests  : %u\n", svcrdma_max_bc_requests);
 	dprintk("\tmax_inline       : %d\n", svcrdma_max_req_size);
 
-	svc_rdma_wq = alloc_workqueue("svc_rdma", 0, 0);
-	if (!svc_rdma_wq)
-		return -ENOMEM;
-
 	if (!svcrdma_table_header)
 		svcrdma_table_header =
 			register_sysctl_table(svcrdma_root_table);
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 4d3db6ee7f09..30dbbc77ad16 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -630,8 +630,9 @@ static void svc_rdma_free(struct svc_xprt *xprt)
 {
 	struct svcxprt_rdma *rdma =
 		container_of(xprt, struct svcxprt_rdma, sc_xprt);
+
 	INIT_WORK(&rdma->sc_work, __svc_rdma_free);
-	queue_work(svc_rdma_wq, &rdma->sc_work);
+	schedule_work(&rdma->sc_work);
 }
 
 static int svc_rdma_has_wspace(struct svc_xprt *xprt)

[PATCH 2/2] svcrdma: Use llist for managing cache of recv_ctxts

[Chuck Lever]

Use a wait-free mechanism for managing the svc_rdma_recv_ctxts free
list. Subsequently, sc_recv_lock can be eliminated.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 include/linux/sunrpc/svc_rdma.h          |    5 +++--
 net/sunrpc/xprtrdma/svc_rdma_recvfrom.c  |   24 ++++++++++--------------
 net/sunrpc/xprtrdma/svc_rdma_transport.c |    3 +--
 3 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index edb39900fe04..40f65888dd38 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -42,6 +42,7 @@
 
 #ifndef SVC_RDMA_H
 #define SVC_RDMA_H
+#include <linux/llist.h>
 #include <linux/sunrpc/xdr.h>
 #include <linux/sunrpc/svcsock.h>
 #include <linux/sunrpc/rpc_rdma.h>
@@ -107,8 +108,7 @@ struct svcxprt_rdma {
 	struct list_head     sc_read_complete_q;
 	struct work_struct   sc_work;
 
-	spinlock_t	     sc_recv_lock;
-	struct list_head     sc_recv_ctxts;
+	struct llist_head    sc_recv_ctxts;
 };
 /* sc_flags */
 #define RDMAXPRT_CONN_PENDING	3
@@ -125,6 +125,7 @@ enum {
 #define RPCSVC_MAXPAYLOAD_RDMA	RPCSVC_MAXPAYLOAD
 
 struct svc_rdma_recv_ctxt {
+	struct llist_node	rc_node;
 	struct list_head	rc_list;
 	struct ib_recv_wr	rc_recv_wr;
 	struct ib_cqe		rc_cqe;
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index 65e2fb9aac65..96bccd398469 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -172,9 +172,10 @@ static void svc_rdma_recv_ctxt_destroy(struct svcxprt_rdma *rdma,
 void svc_rdma_recv_ctxts_destroy(struct svcxprt_rdma *rdma)
 {
 	struct svc_rdma_recv_ctxt *ctxt;
+	struct llist_node *node;
 
-	while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_recv_ctxts))) {
-		list_del(&ctxt->rc_list);
+	while ((node = llist_del_first(&rdma->sc_recv_ctxts))) {
+		ctxt = llist_entry(node, struct svc_rdma_recv_ctxt, rc_node);
 		svc_rdma_recv_ctxt_destroy(rdma, ctxt);
 	}
 }
@@ -183,21 +184,18 @@ static struct svc_rdma_recv_ctxt *
 svc_rdma_recv_ctxt_get(struct svcxprt_rdma *rdma)
 {
 	struct svc_rdma_recv_ctxt *ctxt;
+	struct llist_node *node;
 
-	spin_lock(&rdma->sc_recv_lock);
-	ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_recv_ctxts);
-	if (!ctxt)
+	node = llist_del_first(&rdma->sc_recv_ctxts);
+	if (!node)
 		goto out_empty;
-	list_del(&ctxt->rc_list);
-	spin_unlock(&rdma->sc_recv_lock);
+	ctxt = llist_entry(node, struct svc_rdma_recv_ctxt, rc_node);
 
 out:
 	ctxt->rc_page_count = 0;
 	return ctxt;
 
 out_empty:
-	spin_unlock(&rdma->sc_recv_lock);
-
 	ctxt = svc_rdma_recv_ctxt_alloc(rdma);
 	if (!ctxt)
 		return NULL;
@@ -218,11 +216,9 @@ void svc_rdma_recv_ctxt_put(struct svcxprt_rdma *rdma,
 	for (i = 0; i < ctxt->rc_page_count; i++)
 		put_page(ctxt->rc_pages[i]);
 
-	if (!ctxt->rc_temp) {
-		spin_lock(&rdma->sc_recv_lock);
-		list_add(&ctxt->rc_list, &rdma->sc_recv_ctxts);
-		spin_unlock(&rdma->sc_recv_lock);
-	} else
+	if (!ctxt->rc_temp)
+		llist_add(&ctxt->rc_node, &rdma->sc_recv_ctxts);
+	else
 		svc_rdma_recv_ctxt_destroy(rdma, ctxt);
 }
 
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 30dbbc77ad16..145a3615c319 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -140,14 +140,13 @@ static struct svcxprt_rdma *svc_rdma_create_xprt(struct svc_serv *serv,
 	INIT_LIST_HEAD(&cma_xprt->sc_rq_dto_q);
 	INIT_LIST_HEAD(&cma_xprt->sc_read_complete_q);
 	INIT_LIST_HEAD(&cma_xprt->sc_send_ctxts);
-	INIT_LIST_HEAD(&cma_xprt->sc_recv_ctxts);
+	init_llist_head(&cma_xprt->sc_recv_ctxts);
 	INIT_LIST_HEAD(&cma_xprt->sc_rw_ctxts);
 	init_waitqueue_head(&cma_xprt->sc_send_wait);
 
 	spin_lock_init(&cma_xprt->sc_lock);
 	spin_lock_init(&cma_xprt->sc_rq_dto_lock);
 	spin_lock_init(&cma_xprt->sc_send_lock);
-	spin_lock_init(&cma_xprt->sc_recv_lock);
 	spin_lock_init(&cma_xprt->sc_rw_ctxt_lock);
 
 	/*

Re: [PATCH 1/2] svcrdma: Remove svc_rdma_wq

[J. Bruce Fields]

Thanks!  Applying both for 5.4.

--b.

On Fri, Aug 16, 2019 at 05:48:36PM -0400, Chuck Lever wrote:
> Clean up: the system workqueue will work just as well.
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  include/linux/sunrpc/svc_rdma.h          |    1 -
>  net/sunrpc/xprtrdma/svc_rdma.c           |    7 -------
>  net/sunrpc/xprtrdma/svc_rdma_transport.c |    3 ++-
>  3 files changed, 2 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
> index 981f0d726ad4..edb39900fe04 100644
> --- a/include/linux/sunrpc/svc_rdma.h
> +++ b/include/linux/sunrpc/svc_rdma.h
> @@ -200,7 +200,6 @@ extern struct svc_xprt_class svc_rdma_bc_class;
>  #endif
>  
>  /* svc_rdma.c */
> -extern struct workqueue_struct *svc_rdma_wq;
>  extern int svc_rdma_init(void);
>  extern void svc_rdma_cleanup(void);
>  
> diff --git a/net/sunrpc/xprtrdma/svc_rdma.c b/net/sunrpc/xprtrdma/svc_rdma.c
> index abdb3004a1e3..97bca509a391 100644
> --- a/net/sunrpc/xprtrdma/svc_rdma.c
> +++ b/net/sunrpc/xprtrdma/svc_rdma.c
> @@ -73,8 +73,6 @@ atomic_t rdma_stat_rq_prod;
>  atomic_t rdma_stat_sq_poll;
>  atomic_t rdma_stat_sq_prod;
>  
> -struct workqueue_struct *svc_rdma_wq;
> -
>  /*
>   * This function implements reading and resetting an atomic_t stat
>   * variable through read/write to a proc file. Any write to the file
> @@ -230,7 +228,6 @@ static struct ctl_table svcrdma_root_table[] = {
>  void svc_rdma_cleanup(void)
>  {
>  	dprintk("SVCRDMA Module Removed, deregister RPC RDMA transport\n");
> -	destroy_workqueue(svc_rdma_wq);
>  	if (svcrdma_table_header) {
>  		unregister_sysctl_table(svcrdma_table_header);
>  		svcrdma_table_header = NULL;
> @@ -246,10 +243,6 @@ int svc_rdma_init(void)
>  	dprintk("\tmax_bc_requests  : %u\n", svcrdma_max_bc_requests);
>  	dprintk("\tmax_inline       : %d\n", svcrdma_max_req_size);
>  
> -	svc_rdma_wq = alloc_workqueue("svc_rdma", 0, 0);
> -	if (!svc_rdma_wq)
> -		return -ENOMEM;
> -
>  	if (!svcrdma_table_header)
>  		svcrdma_table_header =
>  			register_sysctl_table(svcrdma_root_table);
> diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
> index 4d3db6ee7f09..30dbbc77ad16 100644
> --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
> +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
> @@ -630,8 +630,9 @@ static void svc_rdma_free(struct svc_xprt *xprt)
>  {
>  	struct svcxprt_rdma *rdma =
>  		container_of(xprt, struct svcxprt_rdma, sc_xprt);
> +
>  	INIT_WORK(&rdma->sc_work, __svc_rdma_free);
> -	queue_work(svc_rdma_wq, &rdma->sc_work);
> +	schedule_work(&rdma->sc_work);
>  }
>  
>  static int svc_rdma_has_wspace(struct svc_xprt *xprt)