linux-kernel - [PATCH 3.10 170/180] ubi: Fix race condition between ubi device creation and udev

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Date:   Sun, 21 Aug 2016 17:31:40 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Iosif Harutyunov <iharutyunov@...icwall.com>,
        Iosif Harutyunov <iharutyunov@...icwall.com>,
        Richard Weinberger <richard@....at>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 170/180] ubi: Fix race condition between ubi device creation and udev

From: Iosif Harutyunov <iharutyunov@...icWALL.com>

commit 714fb87e8bc05ff78255afc0dca981e8c5242785 upstream.

Install the UBI device object before we arm sysfs.
Otherwise udev tries to read sysfs attributes before UBI is ready and
udev rules will not match.

Cc: <stable@...r.kernel.org>
Signed-off-by: Iosif Harutyunov <iharutyunov@...icwall.com>
[rw: massaged commit message]
Signed-off-by: Richard Weinberger <richard@....at>
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/mtd/ubi/build.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index a561335..03331c1 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -997,6 +997,9 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 			goto out_detach;
 	}
 
+	/* Make device "available" before it becomes accessible via sysfs */
+	ubi_devices[ubi_num] = ubi;
+
 	err = uif_init(ubi, &ref);
 	if (err)
 		goto out_detach;
@@ -1041,7 +1044,6 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 	wake_up_process(ubi->bgt_thread);
 	spin_unlock(&ubi->wl_lock);
 
-	ubi_devices[ubi_num] = ubi;
 	ubi_notify_all(ubi, UBI_VOLUME_ADDED, NULL);
 	return ubi_num;
 
@@ -1052,6 +1054,7 @@ out_uif:
 	ubi_assert(ref);
 	uif_close(ubi);
 out_detach:
+	ubi_devices[ubi_num] = NULL;
 	ubi_wl_close(ubi);
 	ubi_free_internal_volumes(ubi);
 	vfree(ubi->vtbl);
-- 
2.8.0.rc2.1.gbe9624a