ipc: msg: Make msg_queue timestamps y2038 safe

time_t is not y2038 safe. Replace all uses of
time_t by y2038 safe time64_t.

Similarly, replace the calls to get_seconds() with
y2038 safe ktime_get_real_seconds().
Note that this preserves fast access on 64 bit systems,
but 32 bit systems need sequence counters.

The syscall interfaces themselves are not changed as part of
the patch. They will be part of a different series.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/msg.h

@@ -2,6 +2,7 @@
 #define _LINUX_MSG_H
 
 #include <linux/list.h>
+#include <linux/time64.h>
 #include <uapi/linux/msg.h>
 
 /* one msg_msg structure for each message */
@@ -17,9 +18,9 @@ struct msg_msg {
 /* one msq_queue structure for each present queue on the system */
 struct msg_queue {
 	struct kern_ipc_perm q_perm;
-	time_t q_stime;			/* last msgsnd time */
-	time_t q_rtime;			/* last msgrcv time */
-	time_t q_ctime;			/* last change time */
+	time64_t q_stime;		/* last msgsnd time */
+	time64_t q_rtime;		/* last msgrcv time */
+	time64_t q_ctime;		/* last change time */
 	unsigned long q_cbytes;		/* current number of bytes on queue */
 	unsigned long q_qnum;		/* number of messages in queue */
 	unsigned long q_qbytes;		/* max number of bytes on queue */

ipc/msg.c

@@ -133,7 +133,7 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 	}
 
 	msq->q_stime = msq->q_rtime = 0;
-	msq->q_ctime = get_seconds();
+	msq->q_ctime = ktime_get_real_seconds();
 	msq->q_cbytes = msq->q_qnum = 0;
 	msq->q_qbytes = ns->msg_ctlmnb;
 	msq->q_lspid = msq->q_lrpid = 0;
@@ -406,7 +406,7 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
 
 		msq->q_qbytes = msqid64->msg_qbytes;
 
-		msq->q_ctime = get_seconds();
+		msq->q_ctime = ktime_get_real_seconds();
 		/*
 		 * Sleeping receivers might be excluded by
 		 * stricter permissions.
@@ -1181,7 +1181,7 @@ static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
 	struct msg_queue *msq = it;
 
 	seq_printf(s,
-		   "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
+		   "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
 		   msq->q_perm.key,
 		   msq->q_perm.id,
 		   msq->q_perm.mode,