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Date: Wed, 29 Aug 2018 21:19:40 +0200
From: Jakub Kicinski <jakub.kicinski@...ronome.com>
To: Björn Töpel <bjorn.topel@...il.com>
Cc: magnus.karlsson@...el.com, magnus.karlsson@...il.com,
alexander.h.duyck@...el.com, alexander.duyck@...il.com,
ast@...nel.org, brouer@...hat.com, daniel@...earbox.net,
netdev@...r.kernel.org, jesse.brandeburg@...el.com,
anjali.singhai@...el.com, peter.waskiewicz.jr@...el.com,
Björn Töpel <bjorn.topel@...el.com>,
michael.lundkvist@...csson.com, willemdebruijn.kernel@...il.com,
john.fastabend@...il.com, neerav.parikh@...el.com,
mykyta.iziumtsev@...aro.org, francois.ozog@...aro.org,
ilias.apalodimas@...aro.org, brian.brooks@...aro.org,
u9012063@...il.com, pavel@...tnetmon.com, qi.z.zhang@...el.com
Subject: [RFC] net: xsk: add a simple buffer reuse queue
XSK UMEM is strongly single producer single consumer so reuse of
frames is challenging. Add a simple "stash" of FILL packets to
reuse for drivers to optionally make use of. This is useful
when driver has to free (ndo_stop) or resize a ring with an active
AF_XDP ZC socket.
Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
---
include/net/xdp_sock.h | 44 +++++++++++++++++++++++++++++++++
net/xdp/xdp_umem.c | 2 ++
net/xdp/xsk_queue.c | 56 ++++++++++++++++++++++++++++++++++++++++++
net/xdp/xsk_queue.h | 3 +++
4 files changed, 105 insertions(+)
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 6871e4755975..108c1c100de4 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -14,6 +14,7 @@
#include <net/sock.h>
struct net_device;
+struct xdp_umem_fq_reuse;
struct xsk_queue;
struct xdp_umem_props {
@@ -41,6 +42,7 @@ struct xdp_umem {
struct page **pgs;
u32 npgs;
struct net_device *dev;
+ struct xdp_umem_fq_reuse *fq_reuse;
u16 queue_id;
bool zc;
spinlock_t xsk_list_lock;
@@ -110,4 +112,46 @@ static inline dma_addr_t xdp_umem_get_dma(struct xdp_umem *umem, u64 addr)
return umem->pages[addr >> PAGE_SHIFT].dma + (addr & (PAGE_SIZE - 1));
}
+struct xdp_umem_fq_reuse {
+ u32 nentries;
+ u32 length;
+ u64 handles[];
+};
+
+/* Following functions are not thread-safe in any way */
+struct xdp_umem_fq_reuse *xsk_reuseq_prepare(u32 nentries);
+struct xdp_umem_fq_reuse *xsk_reuseq_swap(struct xdp_umem *umem,
+ struct xdp_umem_fq_reuse *newq);
+void xsk_reuseq_free(struct xdp_umem_fq_reuse *rq);
+
+/* Reuse-queue aware version of FILL queue helpers */
+static inline u64 *xsk_umem_peek_addr_rq(struct xdp_umem *umem, u64 *addr)
+{
+ struct xdp_umem_fq_reuse *rq = umem->fq_reuse;
+
+ if (!rq->length) {
+ return xsk_umem_peek_addr(umem, addr);
+ } else {
+ *addr = rq->handles[rq->length - 1];
+ return addr;
+ }
+}
+
+static inline void xsk_umem_discard_addr_rq(struct xdp_umem *umem)
+{
+ struct xdp_umem_fq_reuse *rq = umem->fq_reuse;
+
+ if (!rq->length)
+ xsk_umem_discard_addr(umem);
+ else
+ rq->length--;
+}
+
+static inline void xsk_umem_fq_reuse(struct xdp_umem *umem, u64 addr)
+{
+ struct xdp_umem_fq_reuse *rq = umem->fq_reuse;
+
+ rq->handles[rq->length++] = addr;
+}
+
#endif /* _LINUX_XDP_SOCK_H */
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index e762310c9bee..40303e24c954 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -170,6 +170,8 @@ static void xdp_umem_release(struct xdp_umem *umem)
umem->cq = NULL;
}
+ xsk_reuseq_destroy(umem);
+
xdp_umem_unpin_pages(umem);
task = get_pid_task(umem->pid, PIDTYPE_PID);
diff --git a/net/xdp/xsk_queue.c b/net/xdp/xsk_queue.c
index 6c32e92e98fc..f9ee40a13a9a 100644
--- a/net/xdp/xsk_queue.c
+++ b/net/xdp/xsk_queue.c
@@ -3,7 +3,9 @@
* Copyright(c) 2018 Intel Corporation.
*/
+#include <linux/log2.h>
#include <linux/slab.h>
+#include <linux/overflow.h>
#include "xsk_queue.h"
@@ -61,3 +63,57 @@ void xskq_destroy(struct xsk_queue *q)
page_frag_free(q->ring);
kfree(q);
}
+
+struct xdp_umem_fq_reuse *xsk_reuseq_prepare(u32 nentries)
+{
+ struct xdp_umem_fq_reuse *newq;
+
+ /* Check for overflow */
+ if (nentries > (u32)roundup_pow_of_two(nentries))
+ return NULL;
+ nentries = roundup_pow_of_two(nentries);
+
+ newq = kvmalloc(struct_size(newq, handles, nentries), GFP_KERNEL);
+ if (!newq)
+ return NULL;
+ memset(newq, 0, offsetof(typeof(*newq), handles));
+
+ newq->nentries = nentries;
+ return newq;
+}
+EXPORT_SYMBOL_GPL(xsk_reuseq_prepare);
+
+struct xdp_umem_fq_reuse *xsk_reuseq_swap(struct xdp_umem *umem,
+ struct xdp_umem_fq_reuse *newq)
+{
+ struct xdp_umem_fq_reuse *oldq = umem->fq_reuse;
+
+ if (!oldq) {
+ umem->fq_reuse = newq;
+ return NULL;
+ }
+
+ if (newq->nentries < oldq->length)
+ return newq;
+
+
+ memcpy(newq->handles, oldq->handles,
+ array_size(oldq->length, sizeof(u64)));
+ newq->length = oldq->length;
+
+ umem->fq_reuse = newq;
+ return oldq;
+}
+EXPORT_SYMBOL_GPL(xsk_reuseq_swap);
+
+void xsk_reuseq_free(struct xdp_umem_fq_reuse *rq)
+{
+ kvfree(rq);
+}
+EXPORT_SYMBOL_GPL(xsk_reuseq_free);
+
+void xsk_reuseq_destroy(struct xdp_umem *umem)
+{
+ xsk_reuseq_free(umem->fq_reuse);
+ umem->fq_reuse = NULL;
+}
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 8a64b150be54..7a480e3eb35d 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -257,4 +257,7 @@ void xskq_set_umem(struct xsk_queue *q, struct xdp_umem_props *umem_props);
struct xsk_queue *xskq_create(u32 nentries, bool umem_queue);
void xskq_destroy(struct xsk_queue *q_ops);
+/* Executed by the core when the entire UMEM gets freed */
+void xsk_reuseq_destroy(struct xdp_umem *umem);
+
#endif /* _LINUX_XSK_QUEUE_H */
--
2.17.1
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