IB/{rdmavt, hfi1, qib}: Fix panic with post receive and SGE compression

The server side of qperf panics as follows:

[242446.336860] IP: report_bug+0x64/0x10
[242446.341031] PGD 1c0c067
[242446.341032] P4D 1c0c067
[242446.343951] PUD 1c0d063
[242446.346870] PMD 8587ea067
[242446.349788] PTE 800000083e14016
[242446.352901]
[242446.358352] Oops: 0003 [#1] SM
[242446.437919] CPU: 1 PID: 7442 Comm: irq/92-hfi1_0 k Not tainted 4.12.0-mam-asm #1
[242446.446365] Hardware name: Intel Corporation S2600WT2/S2600WT2, BIOS SE5C610.86B.01.01.0018.C4.072020161249 07/20/201
[242446.458397] task: ffff8808392d2b80 task.stack: ffffc9000664000
[242446.465097] RIP: 0010:report_bug+0x64/0x10
[242446.469859] RSP: 0018:ffffc900066439c0 EFLAGS: 0001000
[242446.475784] RAX: ffffffffa06647e4 RBX: ffffffffa06461e1 RCX: 000000000000000
[242446.483840] RDX: 0000000000000907 RSI: ffffffffa0675040 RDI: ffffffffffff740
[242446.491897] RBP: ffffc900066439e0 R08: 0000000000000001 R09: 000000000000025
[242446.499953] R10: ffffffff81a253df R11: 0000000000000133 R12: ffffc90006643b3
[242446.508010] R13: ffffffffa065bbf0 R14: 00000000000001e5 R15: 000000000000000
[242446.516067] FS:  0000000000000000(0000) GS:ffff88085f640000(0000) knlGS:000000000000000
[242446.525191] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003
[242446.531698] CR2: ffffffffa06647ee CR3: 0000000001c09000 CR4: 00000000001406e
[242446.539756] Call Trace
[242446.542582]  fixup_bug+0x2c/0x5
[242446.546277]  do_trap+0x12b/0x18
[242446.549972]  do_error_trap+0x89/0x11
[242446.554171]  ? hfi1_copy_sge+0x271/0x2b0 [hfi1
[242446.559324]  ? ttwu_do_wakeup+0x1e/0x14
[242446.563795]  ? ttwu_do_activate+0x77/0x8
[242446.568363]  do_invalid_op+0x20/0x3
[242446.572448]  invalid_op+0x1e/0x3
[242446.576247] RIP: 0010:hfi1_copy_sge+0x271/0x2b0 [hfi1
[242446.582075] RSP: 0018:ffffc90006643be8 EFLAGS: 0001004
[242446.587999] RAX: 0000000000000000 RBX: ffff88083e0fa240 RCX: 000000000000000
[242446.596058] RDX: 0000000000000000 RSI: ffff880842508000 RDI: ffff88083e0fa24
[242446.604116] RBP: ffffc90006643c28 R08: 0000000000000000 R09: 000000000000000
[242446.612172] R10: ffffc90009473640 R11: 0000000000000133 R12: 000000000000000
[242446.620228] R13: 0000000000000000 R14: 0000000000002000 R15: ffff88084250800
[242446.628293]  ? hfi1_copy_sge+0x1a1/0x2b0 [hfi1
[242446.633449]  hfi1_rc_rcv+0x3da/0x1270 [hfi1
[242446.638312]  ? sc_buffer_alloc+0x113/0x150 [hfi1
[242446.643662]  hfi1_ib_rcv+0x1c9/0x2e0 [hfi1
[242446.648428]  process_receive_ib+0x19a/0x270 [hfi1
[242446.653866]  ? process_rcv_qp_work+0xd2/0x160 [hfi1
[242446.659505]  handle_receive_interrupt_nodma_rtail+0x184/0x2e0 [hfi1
[242446.666693]  ? irq_finalize_oneshot+0x100/0x10
[242446.671846]  receive_context_thread+0x1b/0x140 [hfi1
[242446.677576]  irq_thread_fn+0x1e/0x4
[242446.681659]  irq_thread+0x13c/0x1b
[242446.685646]  ? irq_forced_thread_fn+0x60/0x6
[242446.690604]  kthread+0x112/0x15
[242446.694298]  ? irq_thread_check_affinity+0xe0/0xe
[242446.699738]  ? kthread_park+0x60/0x6
[242446.703919]  ? do_syscall_64+0x67/0x15
[242446.708292]  ret_from_fork+0x25/0x3
[242446.712374] Code: 63 78 04 44 0f b7 70 08 41 89 d0 4c 8d 2c 38 41 83 e0 01 f6 c2 02 74 17 66 45 85 c0 74 11 f6 c2 04 b9 01 00 00 00 75 bb 83 ca 04 <66> 89 50 0a 66 45 85 c0 74 52 0f b6 48 0b 41 0f b7 f6 4d 89 e0
[242446.733527] RIP: report_bug+0x64/0x100 RSP: ffffc900066439c
[242446.739935] CR2: ffffffffa06647e
[242446.743763] ---[ end trace 0e90a20d0aa494f7 ]--

The root cause is that the qib/hfi1 post receive call to rvt_lkey_ok()
doesn't interpret the new return value from rvt_lkey_ok() properly
leading to an mr reference count underrun.

Additionally, remove an unused argument in rvt_sge_adjacent()
aw well as an unneeded incr local in rvt_post_one_wr().

Fixes: Commit 14fe13fcd3af ("IB/rdmavt: Compress adjacent SGEs in rvt_lkey_ok()")
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/ruc.c

@@ -74,8 +74,10 @@ static int init_sge(struct rvt_qp *qp, struct rvt_rwqe *wqe)
 		if (wqe->sg_list[i].length == 0)
 			continue;
 		/* Check LKEY */
-		if (!rvt_lkey_ok(rkt, pd, j ? &ss->sg_list[j - 1] : &ss->sge,
-				 NULL, &wqe->sg_list[i], IB_ACCESS_LOCAL_WRITE))
+		ret = rvt_lkey_ok(rkt, pd, j ? &ss->sg_list[j - 1] : &ss->sge,
+				  NULL, &wqe->sg_list[i],
+				  IB_ACCESS_LOCAL_WRITE);
+		if (unlikely(ret <= 0))
 			goto bad_lkey;
 		qp->r_len += wqe->sg_list[i].length;
 		j++;

drivers/infiniband/hw/qib/qib_ruc.c

@@ -58,8 +58,10 @@ static int qib_init_sge(struct rvt_qp *qp, struct rvt_rwqe *wqe)
 		if (wqe->sg_list[i].length == 0)
 			continue;
 		/* Check LKEY */
-		if (!rvt_lkey_ok(rkt, pd, j ? &ss->sg_list[j - 1] : &ss->sge,
-				 NULL, &wqe->sg_list[i], IB_ACCESS_LOCAL_WRITE))
+		ret = rvt_lkey_ok(rkt, pd, j ? &ss->sg_list[j - 1] : &ss->sge,
+				  NULL, &wqe->sg_list[i],
+				  IB_ACCESS_LOCAL_WRITE);
+		if (unlikely(ret <= 0))
 			goto bad_lkey;
 		qp->r_len += wqe->sg_list[i].length;
 		j++;

drivers/infiniband/sw/rdmavt/mr.c

@@ -779,7 +779,6 @@ out:
 
 /**
  * rvt_sge_adjacent - is isge compressible
- * @isge: outgoing internal SGE
  * @last_sge: last outgoing SGE written
  * @sge: SGE to check
  *
@@ -787,8 +786,7 @@ out:
  *
  * Return: true if isge is adjacent to last sge
  */
-static inline bool rvt_sge_adjacent(struct rvt_sge *isge,
-				    struct rvt_sge *last_sge,
+static inline bool rvt_sge_adjacent(struct rvt_sge *last_sge,
 				    struct ib_sge *sge)
 {
 	if (last_sge && sge->lkey == last_sge->mr->lkey &&
@@ -840,7 +838,7 @@ int rvt_lkey_ok(struct rvt_lkey_table *rkt, struct rvt_pd *pd,
 
 		if (pd->user)
 			return -EINVAL;
-		if (rvt_sge_adjacent(isge, last_sge, sge))
+		if (rvt_sge_adjacent(last_sge, sge))
 			return 0;
 		rcu_read_lock();
 		mr = rcu_dereference(dev->dma_mr);
@@ -857,7 +855,7 @@ int rvt_lkey_ok(struct rvt_lkey_table *rkt, struct rvt_pd *pd,
 		isge->n = 0;
 		goto ok;
 	}
-	if (rvt_sge_adjacent(isge, last_sge, sge))
+	if (rvt_sge_adjacent(last_sge, sge))
 		return 0;
 	rcu_read_lock();
 	mr = rcu_dereference(rkt->table[sge->lkey >> rkt->shift]);

drivers/infiniband/sw/rdmavt/qp.c

@@ -1613,7 +1613,7 @@ static int rvt_post_one_wr(struct rvt_qp *qp,
 	struct rvt_pd *pd;
 	struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
 	u8 log_pmtu;
-	int ret, incr;
+	int ret;
 	size_t cplen;
 	bool reserved_op;
 	int local_ops_delayed = 0;
@@ -1695,14 +1695,14 @@ static int rvt_post_one_wr(struct rvt_qp *qp,
 
 			if (length == 0)
 				continue;
-			incr = rvt_lkey_ok(rkt, pd, &wqe->sg_list[j], last_sge,
-					   &wr->sg_list[i], acc);
-			if (unlikely(incr < 0))
-				goto bail_lkey_error;
+			ret = rvt_lkey_ok(rkt, pd, &wqe->sg_list[j], last_sge,
+					  &wr->sg_list[i], acc);
+			if (unlikely(ret < 0))
+				goto bail_inval_free;
 			wqe->length += length;
-			if (incr)
+			if (ret)
 				last_sge = &wqe->sg_list[j];
-			j += incr;
+			j += ret;
 		}
 		wqe->wr.num_sge = j;
 	}
@@ -1755,8 +1755,6 @@ static int rvt_post_one_wr(struct rvt_qp *qp,
 
 	return 0;
 
-bail_lkey_error:
-	ret = incr;
 bail_inval_free:
 	/* release mr holds */
 	while (j) {