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Subject[PATCH 4.20 041/183] qed: Fix qed_chain_set_prod() for PBL chains with non power of 2 page count
Date
4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 2d533a9287f2011632977e87ce2783f4c689c984 ]

In PBL chains with non power of 2 page count, the producer is not at the
beginning of the chain when index is 0 after a wrap. Therefore, after the
producer index wrap around, page index should be calculated more carefully.

Signed-off-by: Denis Bolotin <dbolotin@marvell.com>
Signed-off-by: Ariel Elior <aelior@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/qed/qed_chain.h | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)

diff --git a/include/linux/qed/qed_chain.h b/include/linux/qed/qed_chain.h
index 59ddf9af909e4..2dd0a9ed5b361 100644
--- a/include/linux/qed/qed_chain.h
+++ b/include/linux/qed/qed_chain.h
@@ -663,6 +663,37 @@ static inline void *qed_chain_get_last_elem(struct qed_chain *p_chain)
static inline void qed_chain_set_prod(struct qed_chain *p_chain,
u32 prod_idx, void *p_prod_elem)
{
+ if (p_chain->mode == QED_CHAIN_MODE_PBL) {
+ u32 cur_prod, page_mask, page_cnt, page_diff;
+
+ cur_prod = is_chain_u16(p_chain) ? p_chain->u.chain16.prod_idx :
+ p_chain->u.chain32.prod_idx;
+
+ /* Assume that number of elements in a page is power of 2 */
+ page_mask = ~p_chain->elem_per_page_mask;
+
+ /* Use "cur_prod - 1" and "prod_idx - 1" since producer index
+ * reaches the first element of next page before the page index
+ * is incremented. See qed_chain_produce().
+ * Index wrap around is not a problem because the difference
+ * between current and given producer indices is always
+ * positive and lower than the chain's capacity.
+ */
+ page_diff = (((cur_prod - 1) & page_mask) -
+ ((prod_idx - 1) & page_mask)) /
+ p_chain->elem_per_page;
+
+ page_cnt = qed_chain_get_page_cnt(p_chain);
+ if (is_chain_u16(p_chain))
+ p_chain->pbl.c.u16.prod_page_idx =
+ (p_chain->pbl.c.u16.prod_page_idx -
+ page_diff + page_cnt) % page_cnt;
+ else
+ p_chain->pbl.c.u32.prod_page_idx =
+ (p_chain->pbl.c.u32.prod_page_idx -
+ page_diff + page_cnt) % page_cnt;
+ }
+
if (is_chain_u16(p_chain))
p_chain->u.chain16.prod_idx = (u16) prod_idx;
else
--
2.19.1


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