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Subject[PATCH 5.4 114/155] RDMA/mlx5: Fix access to wrong pointer while performing flush due to error
Date
From: Leon Romanovsky <leonro@mellanox.com>

commit 950bf4f17725556bbc773a5b71e88a6c14c9ff25 upstream.

The main difference between send and receive SW completions is related to
separate treatment of WQ queue. For receive completions, the initial index
to be flushed is stored in "tail", while for send completions, it is in
deleted "last_poll".

CPU: 54 PID: 53405 Comm: kworker/u161:0 Kdump: loaded Tainted: G OE --------- -t - 4.18.0-147.el8.ppc64le #1
Workqueue: ib-comp-unb-wq ib_cq_poll_work [ib_core]
NIP: c000003c7c00a000 LR: c00800000e586af4 CTR: c000003c7c00a000
REGS: c0000036cc9db940 TRAP: 0400 Tainted: G OE --------- -t - (4.18.0-147.el8.ppc64le)
MSR: 9000000010009033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 24004488 XER: 20040000
CFAR: c00800000e586af0 IRQMASK: 0
GPR00: c00800000e586ab4 c0000036cc9dbbc0 c00800000e5f1a00 c0000037d8433800
GPR04: c000003895a26800 c0000037293f2000 0000000000000201 0000000000000011
GPR08: c000003895a26c80 c000003c7c00a000 0000000000000000 c00800000ed30438
GPR12: c000003c7c00a000 c000003fff684b80 c00000000017c388 c00000396ec4be40
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: c00000000151e498 0000000000000010 c000003895a26848 0000000000000010
GPR24: 0000000000000010 0000000000010000 c000003895a26800 0000000000000000
GPR28: 0000000000000010 c0000037d8433800 c000003895a26c80 c000003895a26800
NIP [c000003c7c00a000] 0xc000003c7c00a000
LR [c00800000e586af4] __ib_process_cq+0xec/0x1b0 [ib_core]
Call Trace:
[c0000036cc9dbbc0] [c00800000e586ab4] __ib_process_cq+0xac/0x1b0 [ib_core] (unreliable)
[c0000036cc9dbc40] [c00800000e586c88] ib_cq_poll_work+0x40/0xb0 [ib_core]
[c0000036cc9dbc70] [c000000000171f44] process_one_work+0x2f4/0x5c0
[c0000036cc9dbd10] [c000000000172a0c] worker_thread+0xcc/0x760
[c0000036cc9dbdc0] [c00000000017c52c] kthread+0x1ac/0x1c0
[c0000036cc9dbe30] [c00000000000b75c] ret_from_kernel_thread+0x5c/0x80

Fixes: 8e3b68830186 ("RDMA/mlx5: Delete unreachable handle_atomic code by simplifying SW completion")
Link: https://lore.kernel.org/r/20200318091640.44069-1-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/infiniband/hw/mlx5/cq.c | 27 +++++++++++++++++++++++++--
drivers/infiniband/hw/mlx5/mlx5_ib.h | 1 +
drivers/infiniband/hw/mlx5/qp.c | 1 +
3 files changed, 27 insertions(+), 2 deletions(-)

--- a/drivers/infiniband/hw/mlx5/cq.c
+++ b/drivers/infiniband/hw/mlx5/cq.c
@@ -330,6 +330,22 @@ static void mlx5_handle_error_cqe(struct
dump_cqe(dev, cqe);
}

+static void handle_atomics(struct mlx5_ib_qp *qp, struct mlx5_cqe64 *cqe64,
+ u16 tail, u16 head)
+{
+ u16 idx;
+
+ do {
+ idx = tail & (qp->sq.wqe_cnt - 1);
+ if (idx == head)
+ break;
+
+ tail = qp->sq.w_list[idx].next;
+ } while (1);
+ tail = qp->sq.w_list[idx].next;
+ qp->sq.last_poll = tail;
+}
+
static void free_cq_buf(struct mlx5_ib_dev *dev, struct mlx5_ib_cq_buf *buf)
{
mlx5_frag_buf_free(dev->mdev, &buf->frag_buf);
@@ -368,7 +384,7 @@ static void get_sig_err_item(struct mlx5
}

static void sw_comp(struct mlx5_ib_qp *qp, int num_entries, struct ib_wc *wc,
- int *npolled, int is_send)
+ int *npolled, bool is_send)
{
struct mlx5_ib_wq *wq;
unsigned int cur;
@@ -383,10 +399,16 @@ static void sw_comp(struct mlx5_ib_qp *q
return;

for (i = 0; i < cur && np < num_entries; i++) {
- wc->wr_id = wq->wrid[wq->tail & (wq->wqe_cnt - 1)];
+ unsigned int idx;
+
+ idx = (is_send) ? wq->last_poll : wq->tail;
+ idx &= (wq->wqe_cnt - 1);
+ wc->wr_id = wq->wrid[idx];
wc->status = IB_WC_WR_FLUSH_ERR;
wc->vendor_err = MLX5_CQE_SYNDROME_WR_FLUSH_ERR;
wq->tail++;
+ if (is_send)
+ wq->last_poll = wq->w_list[idx].next;
np++;
wc->qp = &qp->ibqp;
wc++;
@@ -476,6 +498,7 @@ repoll:
wqe_ctr = be16_to_cpu(cqe64->wqe_counter);
idx = wqe_ctr & (wq->wqe_cnt - 1);
handle_good_req(wc, cqe64, wq, idx);
+ handle_atomics(*cur_qp, cqe64, wq->last_poll, idx);
wc->wr_id = wq->wrid[idx];
wq->tail = wq->wqe_head[idx] + 1;
wc->status = IB_WC_SUCCESS;
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -283,6 +283,7 @@ struct mlx5_ib_wq {
unsigned head;
unsigned tail;
u16 cur_post;
+ u16 last_poll;
void *cur_edge;
};

--- a/drivers/infiniband/hw/mlx5/qp.c
+++ b/drivers/infiniband/hw/mlx5/qp.c
@@ -3725,6 +3725,7 @@ static int __mlx5_ib_modify_qp(struct ib
qp->sq.cur_post = 0;
if (qp->sq.wqe_cnt)
qp->sq.cur_edge = get_sq_edge(&qp->sq, 0);
+ qp->sq.last_poll = 0;
qp->db.db[MLX5_RCV_DBR] = 0;
qp->db.db[MLX5_SND_DBR] = 0;
}

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