[PATCH] RDMA/siw: Reuse value read using READ_ONCE instead of re-reading it

From: linke li
Date: Sat Mar 09 2024 - 07:29:42 EST


In siw_orqe_start_rx, the orqe's flag in the if condition is read using
READ_ONCE, checked, and then re-read, voiding all guarantees of the
checks. Reuse the value that was read by READ_ONCE to ensure the
consistency of the flags throughout the function.

Signed-off-by: linke li <lilinke99@xxxxxx>
---
drivers/infiniband/sw/siw/siw_qp_rx.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw_qp_rx.c b/drivers/infiniband/sw/siw/siw_qp_rx.c
index ed4fc39718b4..f5f69de56882 100644
--- a/drivers/infiniband/sw/siw/siw_qp_rx.c
+++ b/drivers/infiniband/sw/siw/siw_qp_rx.c
@@ -740,6 +740,7 @@ static int siw_orqe_start_rx(struct siw_qp *qp)
{
struct siw_sqe *orqe;
struct siw_wqe *wqe = NULL;
+ u16 orqe_flags;

if (unlikely(!qp->attrs.orq_size))
return -EPROTO;
@@ -748,7 +749,8 @@ static int siw_orqe_start_rx(struct siw_qp *qp)
smp_mb();

orqe = orq_get_current(qp);
- if (READ_ONCE(orqe->flags) & SIW_WQE_VALID) {
+ orqe_flags = READ_ONCE(orqe->flags);
+ if (orqe_flags & SIW_WQE_VALID) {
/* RRESP is a TAGGED RDMAP operation */
wqe = rx_wqe(&qp->rx_tagged);
wqe->sqe.id = orqe->id;
@@ -756,7 +758,7 @@ static int siw_orqe_start_rx(struct siw_qp *qp)
wqe->sqe.sge[0].laddr = orqe->sge[0].laddr;
wqe->sqe.sge[0].lkey = orqe->sge[0].lkey;
wqe->sqe.sge[0].length = orqe->sge[0].length;
- wqe->sqe.flags = orqe->flags;
+ wqe->sqe.flags = orqe_flags;
wqe->sqe.num_sge = 1;
wqe->bytes = orqe->sge[0].length;
wqe->processed = 0;
--
2.39.3 (Apple Git-146)