linux-kernel - [PATCH AUTOSEL 4.19 159/172] NTB: perf: Fix race condition when run with ntb

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Message-Id: <20200618012218.607130-159-sashal@kernel.org>
Date:   Wed, 17 Jun 2020 21:22:05 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Logan Gunthorpe <logang@...tatee.com>,
        Allen Hubbe <allenbh@...il.com>,
        Alexander Fomichev <fomichev.ru@...il.com>,
        Jon Mason <jdmason@...zu.us>, Sasha Levin <sashal@...nel.org>,
        linux-ntb@...glegroups.com
Subject: [PATCH AUTOSEL 4.19 159/172] NTB: perf: Fix race condition when run with ntb_test

From: Logan Gunthorpe <logang@...tatee.com>

[ Upstream commit 34d8673a01b053b6231a995a4eec9341163d63be ]

When running ntb_test, the script tries to run the ntb_perf test
immediately after probing the modules. Since adding multi-port support,
this fails seeing the new initialization procedure in ntb_perf
can not complete instantly.

To fix this we add a completion which is waited on when a test is
started. In this way, run can be written any time after the module is
loaded and it will wait for the initialization to complete instead of
sending an error.

Fixes: 5648e56d03fa ("NTB: ntb_perf: Add full multi-port NTB API support")
Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
Acked-by: Allen Hubbe <allenbh@...il.com>
Tested-by: Alexander Fomichev <fomichev.ru@...il.com>
Signed-off-by: Jon Mason <jdmason@...zu.us>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/ntb/test/ntb_perf.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/ntb/test/ntb_perf.c b/drivers/ntb/test/ntb_perf.c
index 62a9a1d44f9f..ad5d3919435c 100644
--- a/drivers/ntb/test/ntb_perf.c
+++ b/drivers/ntb/test/ntb_perf.c
@@ -158,6 +158,8 @@ struct perf_peer {
 	/* NTB connection setup service */
 	struct work_struct	service;
 	unsigned long		sts;
+
+	struct completion init_comp;
 };
 #define to_peer_service(__work) \
 	container_of(__work, struct perf_peer, service)
@@ -549,6 +551,7 @@ static int perf_setup_outbuf(struct perf_peer *peer)
 
 	/* Initialization is finally done */
 	set_bit(PERF_STS_DONE, &peer->sts);
+	complete_all(&peer->init_comp);
 
 	return 0;
 }
@@ -640,6 +643,7 @@ static void perf_service_work(struct work_struct *work)
 		perf_setup_outbuf(peer);
 
 	if (test_and_clear_bit(PERF_CMD_CLEAR, &peer->sts)) {
+		init_completion(&peer->init_comp);
 		clear_bit(PERF_STS_DONE, &peer->sts);
 		if (test_bit(0, &peer->perf->busy_flag) &&
 		    peer == peer->perf->test_peer) {
@@ -1047,8 +1051,9 @@ static int perf_submit_test(struct perf_peer *peer)
 	struct perf_thread *pthr;
 	int tidx, ret;
 
-	if (!test_bit(PERF_STS_DONE, &peer->sts))
-		return -ENOLINK;
+	ret = wait_for_completion_interruptible(&peer->init_comp);
+	if (ret < 0)
+		return ret;
 
 	if (test_and_set_bit_lock(0, &perf->busy_flag))
 		return -EBUSY;
@@ -1414,6 +1419,7 @@ static int perf_init_peers(struct perf_ctx *perf)
 			peer->gidx = pidx;
 		}
 		INIT_WORK(&peer->service, perf_service_work);
+		init_completion(&peer->init_comp);
 	}
 	if (perf->gidx == -1)
 		perf->gidx = pidx;
-- 
2.25.1