linux-kernel - [PATCH 3.2 047/152] ubi: Fix race condition between ubi device creation and udev

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Message-ID: <lsq.1479082447.447754611@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:07 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Iosif Harutyunov" <iharutyunov@...icwall.com>,
        "Iosif Harutyunov" <iharutyunov@...icWALL.com>,
        "Richard Weinberger" <richard@....at>
Subject: [PATCH 3.2 047/152] ubi: Fix race condition between ubi device
 creation and udev

3.2.84-rc1 review patch.  If anyone has any objections, please let me know.

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

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.

Signed-off-by: Iosif Harutyunov <iharutyunov@...icwall.com>
[rw: massaged commit message]
Signed-off-by: Richard Weinberger <richard@....at>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/mtd/ubi/build.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -974,6 +974,9 @@ int ubi_attach_mtd_dev(struct mtd_info *
 			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;
@@ -1017,7 +1020,6 @@ int ubi_attach_mtd_dev(struct mtd_info *
 	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;
 
@@ -1028,6 +1030,7 @@ out_uif:
 	ubi_assert(ref);
 	uif_close(ubi);
 out_detach:
+	ubi_devices[ubi_num] = NULL;
 	ubi_wl_close(ubi);
 	free_internal_volumes(ubi);
 	vfree(ubi->vtbl);