[PATCH] ibmvfc: alloc/free queue resource only during probe/remove

[Tyrel Datwyler <tyreld@linux.ibm.com>]

Currently, the sub-queues and event pool resources are alloc/free'd
for every CRQ connection event such as reset and LPM. This exposes the driver to
a couple issues. First the inefficiency of freeing and reallocating memory that
can simply be resued after being sanitized. Further, a system under memory
pressue runs the risk of allocation failures that could result in a cripled
driver. Finally, there is a race window where command submission/compeletion can
try to pull/return elements from/to an event pool that is being deleted or
already has been deleted due to the lack of host state around freeing/allocating
resources. The following is an example of list corruption following a live
partition migration (LPM):

Oops: Exception in kernel mode, sig: 5 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in: vfat fat isofs cdrom ext4 mbcache jbd2 nft_counter nft_compat nf_tables nfnetlink rpadlpar_io rpaphp xsk_diag nfsv3 nfs_acl nfs lockd grace fscache netfs rfkill bonding tls sunrpc pseries_rng drm drm_panel_orientation_quirks xfs libcrc32c dm_service_time sd_mod t10_pi sg ibmvfc scsi_transport_fc ibmveth vmx_crypto dm_multipath dm_mirror dm_region_hash dm_log dm_mod ipmi_devintf ipmi_msghandler fuse
CPU: 0 PID: 2108 Comm: ibmvfc_0 Kdump: loaded Not tainted 5.14.0-70.9.1.el9_0.ppc64le #1
NIP: c0000000007c4bb0 LR: c0000000007c4bac CTR: 00000000005b9a10
REGS: c00000025c10b760 TRAP: 0700  Not tainted (5.14.0-70.9.1.el9_0.ppc64le)
MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 2800028f XER: 0000000f
CFAR: c0000000001f55bc IRQMASK: 0
        GPR00: c0000000007c4bac c00000025c10ba00 c000000002a47c00 000000000000004e
        GPR04: c0000031e3006f88 c0000031e308bd00 c00000025c10b768 0000000000000027
        GPR08: 0000000000000000 c0000031e3009dc0 00000031e0eb0000 0000000000000000
        GPR12: c0000031e2ffffa8 c000000002dd0000 c000000000187108 c00000020fcee2c0
        GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
        GPR20: 0000000000000000 0000000000000000 0000000000000000 c008000002f81300
        GPR24: 5deadbeef0000100 5deadbeef0000122 c000000263ba6910 c00000024cc88000
        GPR28: 000000000000003c c0000002430a0000 c0000002430ac300 000000000000c300
NIP [c0000000007c4bb0] __list_del_entry_valid+0x90/0x100
LR [c0000000007c4bac] __list_del_entry_valid+0x8c/0x100
Call Trace:
[c00000025c10ba00] [c0000000007c4bac] __list_del_entry_valid+0x8c/0x100 (unreliable)
[c00000025c10ba60] [c008000002f42284] ibmvfc_free_queue+0xec/0x210 [ibmvfc]
[c00000025c10bb10] [c008000002f4246c] ibmvfc_deregister_scsi_channel+0xc4/0x160 [ibmvfc]
[c00000025c10bba0] [c008000002f42580] ibmvfc_release_sub_crqs+0x78/0x130 [ibmvfc]
[c00000025c10bc20] [c008000002f4f6cc] ibmvfc_do_work+0x5c4/0xc70 [ibmvfc]
[c00000025c10bce0] [c008000002f4fdec] ibmvfc_work+0x74/0x1e8 [ibmvfc]
[c00000025c10bda0] [c0000000001872b8] kthread+0x1b8/0x1c0
[c00000025c10be10] [c00000000000cd64] ret_from_kernel_thread+0x5c/0x64
Instruction dump:
40820034 38600001 38210060 4e800020 7c0802a6 7c641b78 3c62fe7a 7d254b78
3863b590 f8010070 4ba309cd 60000000 <0fe00000> 7c0802a6 3c62fe7a 3863b640
---[ end trace 11a2b65a92f8b66c ]---
ibmvfc 30000003: Send warning. Receive queue closed, will retry.

Add registration/deregistartion helpers that are called instead during
connection resets to sanitize and reconfigure the queues.

Fixes: 3034ebe26389 ("scsi: ibmvfc: Add alloc/dealloc routines for SCSI Sub-CRQ Channels")
Cc: stable@vger.kernel.org
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
---
 drivers/scsi/ibmvscsi/ibmvfc.c | 79 ++++++++++++++++++++++++++--------
 1 file changed, 62 insertions(+), 17 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index 9fc0ffda6ae8..00684e11976b 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -160,8 +160,8 @@ static void ibmvfc_npiv_logout(struct ibmvfc_host *);
 static void ibmvfc_tgt_implicit_logout_and_del(struct ibmvfc_target *);
 static void ibmvfc_tgt_move_login(struct ibmvfc_target *);
 
-static void ibmvfc_release_sub_crqs(struct ibmvfc_host *);
-static void ibmvfc_init_sub_crqs(struct ibmvfc_host *);
+static void ibmvfc_dereg_sub_crqs(struct ibmvfc_host *);
+static void ibmvfc_reg_sub_crqs(struct ibmvfc_host *);
 
 static const char *unknown_error = "unknown error";
 
@@ -917,7 +917,7 @@ static int ibmvfc_reenable_crq_queue(struct ibmvfc_host *vhost)
 	struct vio_dev *vdev = to_vio_dev(vhost->dev);
 	unsigned long flags;
 
-	ibmvfc_release_sub_crqs(vhost);
+	ibmvfc_dereg_sub_crqs(vhost);
 
 	/* Re-enable the CRQ */
 	do {
@@ -936,7 +936,7 @@ static int ibmvfc_reenable_crq_queue(struct ibmvfc_host *vhost)
 	spin_unlock(vhost->crq.q_lock);
 	spin_unlock_irqrestore(vhost->host->host_lock, flags);
 
-	ibmvfc_init_sub_crqs(vhost);
+	ibmvfc_reg_sub_crqs(vhost);
 
 	return rc;
 }
@@ -955,7 +955,7 @@ static int ibmvfc_reset_crq(struct ibmvfc_host *vhost)
 	struct vio_dev *vdev = to_vio_dev(vhost->dev);
 	struct ibmvfc_queue *crq = &vhost->crq;
 
-	ibmvfc_release_sub_crqs(vhost);
+	ibmvfc_dereg_sub_crqs(vhost);
 
 	/* Close the CRQ */
 	do {
@@ -988,7 +988,7 @@ static int ibmvfc_reset_crq(struct ibmvfc_host *vhost)
 	spin_unlock(vhost->crq.q_lock);
 	spin_unlock_irqrestore(vhost->host->host_lock, flags);
 
-	ibmvfc_init_sub_crqs(vhost);
+	ibmvfc_reg_sub_crqs(vhost);
 
 	return rc;
 }
@@ -5759,9 +5759,6 @@ static int ibmvfc_register_scsi_channel(struct ibmvfc_host *vhost,
 
 	ENTER;
 
-	if (ibmvfc_alloc_queue(vhost, scrq, IBMVFC_SUB_CRQ_FMT))
-		return -ENOMEM;
-
 	rc = h_reg_sub_crq(vdev->unit_address, scrq->msg_token, PAGE_SIZE,
 			   &scrq->cookie, &scrq->hw_irq);
 
@@ -5801,7 +5798,6 @@ static int ibmvfc_register_scsi_channel(struct ibmvfc_host *vhost,
 		rc = plpar_hcall_norets(H_FREE_SUB_CRQ, vdev->unit_address, scrq->cookie);
 	} while (rtas_busy_delay(rc));
 reg_failed:
-	ibmvfc_free_queue(vhost, scrq);
 	LEAVE;
 	return rc;
 }
@@ -5827,12 +5823,50 @@ static void ibmvfc_deregister_scsi_channel(struct ibmvfc_host *vhost, int index)
 	if (rc)
 		dev_err(dev, "Failed to free sub-crq[%d]: rc=%ld\n", index, rc);
 
-	ibmvfc_free_queue(vhost, scrq);
+	/* Clean out the queue */
+	memset(scrq->msgs.crq, 0, PAGE_SIZE);
+	scrq->cur = 0;
+
+	LEAVE;
+}
+
+static void ibmvfc_reg_sub_crqs(struct ibmvfc_host *vhost)
+{
+	int i, j;
+
+	ENTER;
+	if (!vhost->mq_enabled || !vhost->scsi_scrqs.scrqs)
+		return;
+
+	for (i = 0; i < nr_scsi_hw_queues; i++) {
+		if (ibmvfc_register_scsi_channel(vhost, i)) {
+			for (j = i; j > 0; j--)
+				ibmvfc_deregister_scsi_channel(vhost, j - 1);
+			vhost->do_enquiry = 0;
+			return;
+		}
+	}
+
+	LEAVE;
+}
+
+static void ibmvfc_dereg_sub_crqs(struct ibmvfc_host *vhost)
+{
+	int i;
+
+	ENTER;
+	if (!vhost->mq_enabled || !vhost->scsi_scrqs.scrqs)
+		return;
+
+	for (i = 0; i < nr_scsi_hw_queues; i++)
+		ibmvfc_deregister_scsi_channel(vhost, i);
+
 	LEAVE;
 }
 
 static void ibmvfc_init_sub_crqs(struct ibmvfc_host *vhost)
 {
+	struct ibmvfc_queue *scrq;
 	int i, j;
 
 	ENTER;
@@ -5848,30 +5882,41 @@ static void ibmvfc_init_sub_crqs(struct ibmvfc_host *vhost)
 	}
 
 	for (i = 0; i < nr_scsi_hw_queues; i++) {
-		if (ibmvfc_register_scsi_channel(vhost, i)) {
-			for (j = i; j > 0; j--)
-				ibmvfc_deregister_scsi_channel(vhost, j - 1);
+		scrq = &vhost->scsi_scrqs.scrqs[i];
+		if (ibmvfc_alloc_queue(vhost, scrq, IBMVFC_SUB_CRQ_FMT)) {
+			for (j = i; j > 0; j--) {
+				scrq = &vhost->scsi_scrqs.scrqs[j - 1];
+				ibmvfc_free_queue(vhost, scrq);
+			}
 			kfree(vhost->scsi_scrqs.scrqs);
 			vhost->scsi_scrqs.scrqs = NULL;
 			vhost->scsi_scrqs.active_queues = 0;
 			vhost->do_enquiry = 0;
-			break;
+			vhost->mq_enabled = 0;
+			return;
 		}
 	}
 
+	ibmvfc_reg_sub_crqs(vhost);
+
 	LEAVE;
 }
 
 static void ibmvfc_release_sub_crqs(struct ibmvfc_host *vhost)
 {
+	struct ibmvfc_queue *scrq;
 	int i;
 
 	ENTER;
 	if (!vhost->scsi_scrqs.scrqs)
 		return;
 
-	for (i = 0; i < nr_scsi_hw_queues; i++)
-		ibmvfc_deregister_scsi_channel(vhost, i);
+	ibmvfc_dereg_sub_crqs(vhost);
+
+	for (i = 0; i < nr_scsi_hw_queues; i++) {
+		scrq = &vhost->scsi_scrqs.scrqs[i];
+		ibmvfc_free_queue(vhost, scrq);
+	}
 
 	kfree(vhost->scsi_scrqs.scrqs);
 	vhost->scsi_scrqs.scrqs = NULL;
-- 
2.35.3