kni: fix kernel FIFO synchronization

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@dpdk.org
Signed-off-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>

diff --git a/kernel/linux/kni/kni_fifo.h b/kernel/linux/kni/kni_fifo.h
index 9a4762d..2cb3a4a 100644 (file)
--- a/kernel/linux/kni/kni_fifo.h
+++ b/kernel/linux/kni/kni_fifo.h
@@ -16,7 +16,7 @@ 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;
 
        for (i = 0; i < num; i++) {
@@ -27,7 +27,7 @@ kni_fifo_put(struct rte_kni_fifo *fifo, void **data, uint32_t num)
                fifo->buffer[fifo_write] = data[i];
                fifo_write = new_write;
        }
-       fifo->write = fifo_write;
+       smp_store_release(&fifo->write, fifo_write);
 
        return i;
 }
@@ -40,7 +40,7 @@ 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++) {
                if (new_read == fifo_write)
@@ -49,7 +49,7 @@ kni_fifo_get(struct rte_kni_fifo *fifo, void **data, uint32_t num)
                data[i] = fifo->buffer[new_read];
                new_read = (new_read + 1) & (fifo->len - 1);
        }
-       fifo->read = new_read;
+       smp_store_release(&fifo->read, new_read);
 
        return i;
 }
@@ -60,7 +60,9 @@ kni_fifo_get(struct rte_kni_fifo *fifo, void **data, uint32_t num)
 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);
 }
 
 /**
@@ -69,7 +71,9 @@ kni_fifo_count(struct rte_kni_fifo *fifo)
 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);
 }
 
 #endif /* _KNI_FIFO_H_ */

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 cfa9448..58e8533 100644 (file)
--- 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
@@ -8,6 +8,7 @@
 
 #ifdef __KERNEL__
 #include <linux/if.h>
+#include <asm/barrier.h>
 #define RTE_STD_C11
 #else
 #include <rte_common.h>