From 845964515a76381e204d3399af82c149f8abcc1c Mon Sep 17 00:00:00 2001
From: Scott Feldman <scofeldm@cisco.com>
Date: Fri, 21 Nov 2008 21:29:01 -0800
Subject: [PATCH] enic: move wmb closer to where needed: before writing
posted_index to hw
Signed-off-by: Scott Feldman <scofeldm@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
drivers/net/enic/enic_res.h | 4 ----
drivers/net/enic/vnic_rq.h | 9 ++++++++-
drivers/net/enic/vnic_wq.h | 9 ++++++++-
3 files changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/net/enic/enic_res.h b/drivers/net/enic/enic_res.h
index 68534a29b7ac..7bf272fa859b 100644
--- a/drivers/net/enic/enic_res.h
+++ b/drivers/net/enic/enic_res.h
@@ -58,8 +58,6 @@ static inline void enic_queue_wq_desc_ex(struct vnic_wq *wq,
(u16)vlan_tag,
0 /* loopback */);
- wmb();
-
vnic_wq_post(wq, os_buf, dma_addr, len, sop, eop);
}
@@ -127,8 +125,6 @@ static inline void enic_queue_rq_desc(struct vnic_rq *rq,
(u64)dma_addr | VNIC_PADDR_TARGET,
type, (u16)len);
- wmb();
-
vnic_rq_post(rq, os_buf, os_buf_index, dma_addr, len);
}
diff --git a/drivers/net/enic/vnic_rq.h b/drivers/net/enic/vnic_rq.h
index 82bfca67cc4d..fd0ef66d2e9f 100644
--- a/drivers/net/enic/vnic_rq.h
+++ b/drivers/net/enic/vnic_rq.h
@@ -132,8 +132,15 @@ static inline void vnic_rq_post(struct vnic_rq *rq,
#define VNIC_RQ_RETURN_RATE 0xf /* keep 2^n - 1 */
#endif
- if ((buf->index & VNIC_RQ_RETURN_RATE) == 0)
+ if ((buf->index & VNIC_RQ_RETURN_RATE) == 0) {
+ /* Adding write memory barrier prevents compiler and/or CPU
+ * reordering, thus avoiding descriptor posting before
+ * descriptor is initialized. Otherwise, hardware can read
+ * stale descriptor fields.
+ */
+ wmb();
iowrite32(buf->index, &rq->ctrl->posted_index);
+ }
}
static inline void vnic_rq_return_descs(struct vnic_rq *rq, unsigned int count)
diff --git a/drivers/net/enic/vnic_wq.h b/drivers/net/enic/vnic_wq.h
index 7081828d8a42..c826137dc651 100644
--- a/drivers/net/enic/vnic_wq.h
+++ b/drivers/net/enic/vnic_wq.h
@@ -108,8 +108,15 @@ static inline void vnic_wq_post(struct vnic_wq *wq,
buf->len = len;
buf = buf->next;
- if (eop)
+ if (eop) {
+ /* Adding write memory barrier prevents compiler and/or CPU
+ * reordering, thus avoiding descriptor posting before
+ * descriptor is initialized. Otherwise, hardware can read
+ * stale descriptor fields.
+ */
+ wmb();
iowrite32(buf->index, &wq->ctrl->posted_index);
+ }
wq->to_use = buf;
wq->ring.desc_avail--;
--
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