linux-kernel - [PATCH AUTOSEL 5.4 211/330] IB/iser: Always check sig MR before putting it to the free pool

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Date:   Thu, 17 Sep 2020 21:59:11 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Sergey Gorenko <sergeygo@...lanox.com>,
        Max Gurtovoy <maxg@...lanox.com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Sasha Levin <sashal@...nel.org>, linux-rdma@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 211/330] IB/iser: Always check sig MR before putting it to the free pool

From: Sergey Gorenko <sergeygo@...lanox.com>

[ Upstream commit 26e28deb813eed908cf31a6052870b6493ec0e86 ]

libiscsi calls the check_protection transport handler only if SCSI-Respose
is received. So, the handler is never called if iSCSI task is completed
for some other reason like a timeout or error handling. And this behavior
looks correct. But the iSER does not handle this case properly because it
puts a non-checked signature MR to the free pool. Then the error occurs at
reusing the MR because it is not allowed to invalidate a signature MR
without checking.

This commit adds an extra check to iser_unreg_mem_fastreg(), which is a
part of the task cleanup flow. Now the signature MR is checked there if it
is needed.

Link: https://lore.kernel.org/r/20200325151210.1548-1-sergeygo@mellanox.com
Signed-off-by: Sergey Gorenko <sergeygo@...lanox.com>
Reviewed-by: Max Gurtovoy <maxg@...lanox.com>
Signed-off-by: Jason Gunthorpe <jgg@...lanox.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/infiniband/ulp/iser/iser_memory.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/ulp/iser/iser_memory.c b/drivers/infiniband/ulp/iser/iser_memory.c
index 2cc89a9b9e9bb..ea8e611397a3b 100644
--- a/drivers/infiniband/ulp/iser/iser_memory.c
+++ b/drivers/infiniband/ulp/iser/iser_memory.c
@@ -292,12 +292,27 @@ void iser_unreg_mem_fastreg(struct iscsi_iser_task *iser_task,
 {
 	struct iser_device *device = iser_task->iser_conn->ib_conn.device;
 	struct iser_mem_reg *reg = &iser_task->rdma_reg[cmd_dir];
+	struct iser_fr_desc *desc;
+	struct ib_mr_status mr_status;
 
-	if (!reg->mem_h)
+	desc = reg->mem_h;
+	if (!desc)
 		return;
 
-	device->reg_ops->reg_desc_put(&iser_task->iser_conn->ib_conn,
-				     reg->mem_h);
+	/*
+	 * The signature MR cannot be invalidated and reused without checking.
+	 * libiscsi calls the check_protection transport handler only if
+	 * SCSI-Response is received. And the signature MR is not checked if
+	 * the task is completed for some other reason like a timeout or error
+	 * handling. That's why we must check the signature MR here before
+	 * putting it to the free pool.
+	 */
+	if (unlikely(desc->sig_protected)) {
+		desc->sig_protected = false;
+		ib_check_mr_status(desc->rsc.sig_mr, IB_MR_CHECK_SIG_STATUS,
+				   &mr_status);
+	}
+	device->reg_ops->reg_desc_put(&iser_task->iser_conn->ib_conn, desc);
 	reg->mem_h = NULL;
 }
 
-- 
2.25.1