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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.16 168/272] powerpc/vas: Fix cleanup when VAS is not configured
Date:   Mon, 28 May 2018 12:03:21 +0200
Message-Id: <20180528100254.901010371@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>

[ Upstream commit 45ddea8a73a25461387eb8e87f3e0ecca084799b ]

When VAS is not configured, unregister the platform driver. Also simplify
cleanup by delaying vas debugfs init until we know VAS is configured.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/powerpc/platforms/powernv/vas-debug.c |   11 +++++++++++
 arch/powerpc/platforms/powernv/vas.c       |    6 +++---
 2 files changed, 14 insertions(+), 3 deletions(-)

--- a/arch/powerpc/platforms/powernv/vas-debug.c
+++ b/arch/powerpc/platforms/powernv/vas-debug.c
@@ -179,6 +179,7 @@ void vas_instance_init_dbgdir(struct vas
 {
 	struct dentry *d;
 
+	vas_init_dbgdir();
 	if (!vas_debugfs)
 		return;
 
@@ -201,8 +202,18 @@ free_name:
 	vinst->dbgdir = NULL;
 }
 
+/*
+ * Set up the "root" VAS debugfs dir. Return if we already set it up
+ * (or failed to) in an earlier instance of VAS.
+ */
 void vas_init_dbgdir(void)
 {
+	static bool first_time = true;
+
+	if (!first_time)
+		return;
+
+	first_time = false;
 	vas_debugfs = debugfs_create_dir("vas", NULL);
 	if (IS_ERR(vas_debugfs))
 		vas_debugfs = NULL;
--- a/arch/powerpc/platforms/powernv/vas.c
+++ b/arch/powerpc/platforms/powernv/vas.c
@@ -160,8 +160,6 @@ static int __init vas_init(void)
 	int found = 0;
 	struct device_node *dn;
 
-	vas_init_dbgdir();
-
 	platform_driver_register(&vas_driver);
 
 	for_each_compatible_node(dn, NULL, "ibm,vas") {
@@ -169,8 +167,10 @@ static int __init vas_init(void)
 		found++;
 	}
 
-	if (!found)
+	if (!found) {
+		platform_driver_unregister(&vas_driver);
 		return -ENODEV;
+	}
 
 	pr_devel("Found %d instances\n", found);