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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: TCNjhlqfyre6CjOSnpHTsYTd3ompa67wKFl6W4z8B5zuhCrIuuWQDPifimGmBq6oSV+1RJZ7Tg8TTNEsT9HW1g6msy/gM+Y/o++vxSd9l/O5JKK4haeHA9Toz4zy7K5V0wZgH/2kBshjyLvTB2aLYFnnx/J6MvI/xc2x5F1aP1i9Hiztr9Iv4KdTdEYGdz3A6bk/58J5Wolo5iUtU08pCiYwuguY77le9DhTfVm4Yjt+sRW21XaWcGTj5KfbGFW6EAdUsajXRevDBr5YKz/YY1fRId3OYZwwlH7GJCUv/f4hWcAv/GWDmotNwlB8anqsCi5PcAkNKs4wpD/NRpf46LNi+0G+QWYNOHnolsmLIGPGcvFYN2hS7yilWM0MRG5d6qPwuaX6+ScZ26q67RDIEEb0GuImg6v+6nCTJ/4G0ASh8AitD0G6SAxsJtJX9xNl X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Sep 2026 15:34:27.6045 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: d68ea436-c05b-421f-1ac7-08df133ed40c X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: MW1PEPF0001615A.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB7643 From: Yishai Hadas __hns_roce_v2_cq_clean() sweeps the CQ backwards from the producer index down to the consumer index: while ((int) --prod_index - (int) hr_cq->cons_index >= 0) Both indexes are free running u32 counters, so the comparison has to be done modulo 2^32. Casting each operand to int and subtracting does not do that: the subtraction overflows whenever the two indexes straddle 2^31, which is undefined behaviour, and a compiler that assumes signed overflow cannot occur is free to discard the subtraction and fold the expression into a plain signed comparison. That comparison is not wraparound safe. The kernel is built with -fno-strict-overflow, so gcc and clang both retain the subtraction today and the generated code is unaffected; there is no known user-visible impact from the current code. Still, correctness here shouldn't depend on that build flag. Replace the loop with a plain unsigned equality check instead: while (prod_index != hr_cq->cons_index) { --prod_index; ... The preceding forward scan starts prod_index at cons_index and advances it only while get_sw_cqe_v2() still reports a software owned entry, so the two indexes stay within one CQ's worth of entries. Decrementing prod_index reaches cons_index in exactly that many iterations regardless of whether either counter has wrapped, because the loop no longer compares magnitudes at all. Signed-off-by: Yishai Hadas Signed-off-by: Edward Srouji --- drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c index 1b2504301ebea4279eb0dcb2537c3574d0122d95..35be5b038f6861f1c330739f5c97817a4c3940a7 100644 --- a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c +++ b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c @@ -3828,7 +3828,8 @@ static void __hns_roce_v2_cq_clean(struct hns_roce_cq *hr_cq, u32 qpn, * Now backwards through the CQ, removing CQ entries * that match our QP by overwriting them with next entries. */ - while ((int) --prod_index - (int) hr_cq->cons_index >= 0) { + while (prod_index != hr_cq->cons_index) { + --prod_index; cqe = get_cqe_v2(hr_cq, prod_index & hr_cq->ib_cq.cqe); if (hr_reg_read(cqe, CQE_LCL_QPN) == qpn) { if (srq && hr_reg_read(cqe, CQE_S_R)) { -- 2.49.0