[dpdk-stable] patch 'kni: fix kernel FIFO synchronization' has been queued to stable release 18.08.1

[Kevin Traynor]

Hi,

FYI, your patch has been queued to stable release 18.08.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 11/28/18. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the patch applied
to the branch. If the code is different (ie: not only metadata diffs), due for example to
a change in context or macro names, please double check it.

Thanks.

Kevin Traynor

---
>From efdbe3a293d9234454070c92036da3cc8de9cceb Mon Sep 17 00:00:00 2001
From: Phil Yang <phil.yang at arm.com>
Date: Mon, 8 Oct 2018 17:11:45 +0800
Subject: [PATCH] kni: fix kernel FIFO synchronization

[ upstream commit 711859cd0d076c7abc0c96ce637129a03280645f ]

Adding memory barrier to make sure the values being synced
before updating fifo_write in kni_fifo_put and fifo_read in
kni_fifo_get.

Fixes: 3fc5ca2f6352 ("kni: initial import")

Signed-off-by: Phil Yang <phil.yang at arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
Reviewed-by: Gavin Hu <gavin.hu at arm.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit at intel.com>
---
 kernel/linux/kni/kni_fifo.h                      | 16 ++++++++++------
 .../eal/include/exec-env/rte_kni_common.h        |  1 +
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/kernel/linux/kni/kni_fifo.h b/kernel/linux/kni/kni_fifo.h
index 9a4762de2..2cb3a4a7b 100644
--- a/kernel/linux/kni/kni_fifo.h
+++ b/kernel/linux/kni/kni_fifo.h
@@ -17,5 +17,5 @@ kni_fifo_put(struct rte_kni_fifo *fifo, void **data, uint32_t num)
 	uint32_t i = 0;
 	uint32_t fifo_write = fifo->write;
-	uint32_t fifo_read = fifo->read;
+	uint32_t fifo_read = smp_load_acquire(&fifo->read);
 	uint32_t new_write = fifo_write;
 
@@ -28,5 +28,5 @@ kni_fifo_put(struct rte_kni_fifo *fifo, void **data, uint32_t num)
 		fifo_write = new_write;
 	}
-	fifo->write = fifo_write;
+	smp_store_release(&fifo->write, fifo_write);
 
 	return i;
@@ -41,5 +41,5 @@ kni_fifo_get(struct rte_kni_fifo *fifo, void **data, uint32_t num)
 	uint32_t i = 0;
 	uint32_t new_read = fifo->read;
-	uint32_t fifo_write = fifo->write;
+	uint32_t fifo_write = smp_load_acquire(&fifo->write);
 
 	for (i = 0; i < num; i++) {
@@ -50,5 +50,5 @@ kni_fifo_get(struct rte_kni_fifo *fifo, void **data, uint32_t num)
 		new_read = (new_read + 1) & (fifo->len - 1);
 	}
-	fifo->read = new_read;
+	smp_store_release(&fifo->read, new_read);
 
 	return i;
@@ -61,5 +61,7 @@ static inline uint32_t
 kni_fifo_count(struct rte_kni_fifo *fifo)
 {
-	return (fifo->len + fifo->write - fifo->read) & (fifo->len - 1);
+	uint32_t fifo_write = smp_load_acquire(&fifo->write);
+	uint32_t fifo_read = smp_load_acquire(&fifo->read);
+	return (fifo->len + fifo_write - fifo_read) & (fifo->len - 1);
 }
 
@@ -70,5 +72,7 @@ static inline uint32_t
 kni_fifo_free_count(struct rte_kni_fifo *fifo)
 {
-	return (fifo->read - fifo->write - 1) & (fifo->len - 1);
+	uint32_t fifo_write = smp_load_acquire(&fifo->write);
+	uint32_t fifo_read = smp_load_acquire(&fifo->read);
+	return (fifo_read - fifo_write - 1) & (fifo->len - 1);
 }
 
diff --git a/lib/librte_eal/linuxapp/eal/include/exec-env/rte_kni_common.h b/lib/librte_eal/linuxapp/eal/include/exec-env/rte_kni_common.h
index cfa9448bd..58e8533be 100644
--- a/lib/librte_eal/linuxapp/eal/include/exec-env/rte_kni_common.h
+++ b/lib/librte_eal/linuxapp/eal/include/exec-env/rte_kni_common.h
@@ -9,4 +9,5 @@
 #ifdef __KERNEL__
 #include <linux/if.h>
+#include <asm/barrier.h>
 #define RTE_STD_C11
 #else
-- 
2.19.0

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2018-11-22 16:47:33.247181298 +0000
+++ 0038-kni-fix-kernel-FIFO-synchronization.patch	2018-11-22 16:47:32.000000000 +0000
@@ -1,14 +1,15 @@
-From 711859cd0d076c7abc0c96ce637129a03280645f Mon Sep 17 00:00:00 2001
+From efdbe3a293d9234454070c92036da3cc8de9cceb Mon Sep 17 00:00:00 2001
 From: Phil Yang <phil.yang at arm.com>
 Date: Mon, 8 Oct 2018 17:11:45 +0800
 Subject: [PATCH] kni: fix kernel FIFO synchronization
 
+[ upstream commit 711859cd0d076c7abc0c96ce637129a03280645f ]
+
 Adding memory barrier to make sure the values being synced
 before updating fifo_write in kni_fifo_put and fifo_read in
 kni_fifo_get.
 
 Fixes: 3fc5ca2f6352 ("kni: initial import")
-Cc: stable at dpdk.org
 
 Signed-off-by: Phil Yang <phil.yang at arm.com>
 Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>