s390/cio: update chpid descriptor after resource accessibility event

BugLink: http://bugs.launchpad.net/bugs/1768474

commit af2e460a upstream.

Channel path descriptors have been seen as something stable (as
long as the chpid is configured). Recent tests have shown that the
descriptor can also be altered when the link state of a channel path
changes. Thus it is necessary to update the descriptor during
handling of resource accessibility events.

Cc: <stable@vger.kernel.org>
Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/s390/cio/chsc.c

@@ -451,6 +451,7 @@ static void chsc_process_sei_link_incident(struct chsc_sei_nt0_area *sei_area)
 
 static void chsc_process_sei_res_acc(struct chsc_sei_nt0_area *sei_area)
 {
+	struct channel_path *chp;
 	struct chp_link link;
 	struct chp_id chpid;
 	int status;
@@ -463,10 +464,17 @@ static void chsc_process_sei_res_acc(struct chsc_sei_nt0_area *sei_area)
 	chpid.id = sei_area->rsid;
 	/* allocate a new channel path structure, if needed */
 	status = chp_get_status(chpid);
-	if (status < 0)
-		chp_new(chpid);
-	else if (!status)
+	if (!status)
 		return;
+
+	if (status < 0) {
+		chp_new(chpid);
+	} else {
+		chp = chpid_to_chp(chpid);
+		mutex_lock(&chp->lock);
+		chp_update_desc(chp);
+		mutex_unlock(&chp->lock);
+	}
 	memset(&link, 0, sizeof(struct chp_link));
 	link.chpid = chpid;
 	if ((sei_area->vf & 0xc0) != 0) {