From: =?UTF-8?q?Jan=20H=C3=B6ppner?= <hoeppner@linux.ibm.com>
Date: Mon, 18 Jan 2021 17:55:18 +0100
Subject: s390/dasd: Fix inconsistent kobject removal
References: jsc#SLE-13767 bsc#1178420 LTC#185092
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Git-commit: ac55ad2b5fadb6af8826963d7d3331c9950a2608
Patch-mainline: v5.11-rc6

Our intention was to only remove path kobjects whenever a device is
being set offline. However, one corner case was missing.

If a device is disabled and enabled (using the IOCTLs BIODASDDISABLE and
BIODASDENABLE respectively), the enabling process will call
dasd_eckd_reload_device() which itself calls dasd_eckd_read_conf() in
order to update path information. During that update,
dasd_eckd_clear_conf_data() clears all old data and also removes all
kobjects. This will leave us with an inconsistent state of path kobjects
and a subsequent path verification leads to a failing kobject creation.

Fix this by removing kobjects only in the context of offlining a device
as initially intended.

Fixes: 19508b204740 ("s390/dasd: Display FC Endpoint Security information via sysfs")
Reported-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/block/dasd_devmap.c |   20 ++++++++++++++------
 drivers/s390/block/dasd_eckd.c   |    3 ++-
 drivers/s390/block/dasd_int.h    |    2 +-
 3 files changed, 17 insertions(+), 8 deletions(-)

--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -1874,18 +1874,26 @@ void dasd_path_create_kobjects(struct da
 }
 EXPORT_SYMBOL(dasd_path_create_kobjects);
 
-/*
- * As we keep kobjects for the lifetime of a device, this function must not be
- * called anywhere but in the context of offlining a device.
- */
-void dasd_path_remove_kobj(struct dasd_device *device, int chp)
+static void dasd_path_remove_kobj(struct dasd_device *device, int chp)
 {
 	if (device->path[chp].in_sysfs) {
 		kobject_put(&device->path[chp].kobj);
 		device->path[chp].in_sysfs = false;
 	}
 }
-EXPORT_SYMBOL(dasd_path_remove_kobj);
+
+/*
+ * As we keep kobjects for the lifetime of a device, this function must not be
+ * called anywhere but in the context of offlining a device.
+ */
+void dasd_path_remove_kobjects(struct dasd_device *device)
+{
+	int i;
+
+	for (i = 0; i < 8; i++)
+		dasd_path_remove_kobj(device, i);
+}
+EXPORT_SYMBOL(dasd_path_remove_kobjects);
 
 int dasd_add_sysfs_files(struct ccw_device *cdev)
 {
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -1036,7 +1036,6 @@ static void dasd_eckd_clear_conf_data(st
 		device->path[i].ssid = 0;
 		device->path[i].chpid = 0;
 		dasd_path_notoper(device, i);
-		dasd_path_remove_kobj(device, i);
 	}
 }
 
@@ -2173,6 +2172,7 @@ out_err2:
 	device->block = NULL;
 out_err1:
 	dasd_eckd_clear_conf_data(device);
+	dasd_path_remove_kobjects(device);
 	kfree(device->private);
 	device->private = NULL;
 	return rc;
@@ -2191,6 +2191,7 @@ static void dasd_eckd_uncheck_device(str
 	private->vdsneq = NULL;
 	private->gneq = NULL;
 	dasd_eckd_clear_conf_data(device);
+	dasd_path_remove_kobjects(device);
 }
 
 static struct dasd_ccw_req *
--- a/drivers/s390/block/dasd_int.h
+++ b/drivers/s390/block/dasd_int.h
@@ -868,7 +868,7 @@ int dasd_add_sysfs_files(struct ccw_devi
 void dasd_remove_sysfs_files(struct ccw_device *);
 void dasd_path_create_kobj(struct dasd_device *, int);
 void dasd_path_create_kobjects(struct dasd_device *);
-void dasd_path_remove_kobj(struct dasd_device *, int);
+void dasd_path_remove_kobjects(struct dasd_device *);
 
 struct dasd_device *dasd_device_from_cdev(struct ccw_device *);
 struct dasd_device *dasd_device_from_cdev_locked(struct ccw_device *);