rcutorture: Expand failure/close-call grace-period output

With only eight bits per grace-period sequence number, wrap can happen
in 64 grace periods.  This commit therefore increases this to sixteen
bits for normal grace-period sequence numbers and the combined short-form
polling sequence numbers, thus deferring wrap for at least 16,384 grace
periods.  Because expedited grace periods go faster, expand these to 24
bits, deferring wrap for at least 4,194,304 expedited grace periods.
These longer wrap times makes it easier to correlate these numbers to
trace-event output.

Note that the low-order two bits are reserved for intra-grace-period
state, hence the above wrap numbers being a factor of four smaller than
you might expect.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

Author: paulmckrcu

kernel/rcu/rcu.h

@@ -590,8 +590,8 @@ void do_trace_rcu_torture_read(const char *rcutorturename,
 #endif
 static inline void rcu_gp_set_torture_wait(int duration) { }
 #endif
-unsigned long rcutorture_gather_gp_seqs(void);
-void rcutorture_format_gp_seqs(unsigned long seqs, char *cp);
+unsigned long long rcutorture_gather_gp_seqs(void);
+void rcutorture_format_gp_seqs(unsigned long long seqs, char *cp);
 
 #ifdef CONFIG_TINY_SRCU
 

kernel/rcu/rcutorture.c

@@ -273,8 +273,8 @@ struct rt_read_seg {
 	bool rt_preempted;
 	int rt_cpu;
 	int rt_end_cpu;
-	unsigned long rt_gp_seq;
-	unsigned long rt_gp_seq_end;
+	unsigned long long rt_gp_seq;
+	unsigned long long rt_gp_seq_end;
 };
 static int err_segs_recorded;
 static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
@@ -409,8 +409,8 @@ struct rcu_torture_ops {
 	void (*gp_slow_register)(atomic_t *rgssp);
 	void (*gp_slow_unregister)(atomic_t *rgssp);
 	bool (*reader_blocked)(void);
-	unsigned long (*gather_gp_seqs)(void);
-	void (*format_gp_seqs)(unsigned long seqs, char *cp);
+	unsigned long long (*gather_gp_seqs)(void);
+	void (*format_gp_seqs)(unsigned long long seqs, char *cp);
 	long cbflood_max;
 	int irq_capable;
 	int can_boost;
@@ -3678,8 +3678,8 @@ rcu_torture_cleanup(void)
 			}
 			if (IS_ENABLED(CONFIG_RCU_TORTURE_TEST_LOG_GP) &&
 			    cur_ops->gather_gp_seqs && cur_ops->format_gp_seqs) {
-				char buf1[16+1];
-				char buf2[16+1];
+				char buf1[20+1];
+				char buf2[20+1];
 				char sepchar = '-';
 
 				cur_ops->format_gp_seqs(err_segs[i].rt_gp_seq, buf1);

kernel/rcu/tiny.c

@@ -258,15 +258,15 @@ EXPORT_SYMBOL_GPL(kvfree_call_rcu);
 #endif
 
 #if IS_ENABLED(CONFIG_RCU_TORTURE_TEST)
-unsigned long rcutorture_gather_gp_seqs(void)
+unsigned long long rcutorture_gather_gp_seqs(void)
 {
-	return READ_ONCE(rcu_ctrlblk.gp_seq) & 0xff;
+	return READ_ONCE(rcu_ctrlblk.gp_seq) & 0xffffULL;
 }
 EXPORT_SYMBOL_GPL(rcutorture_gather_gp_seqs);
 
-void rcutorture_format_gp_seqs(unsigned long seqs, char *cp)
+void rcutorture_format_gp_seqs(unsigned long long seqs, char *cp)
 {
-	snprintf(cp, 8, "g%02lx", seqs & 0xff);
+	snprintf(cp, 8, "g%04llx", seqs & 0xffffULL);
 }
 EXPORT_SYMBOL_GPL(rcutorture_format_gp_seqs);
 #endif

kernel/rcu/tree.c

@@ -539,22 +539,22 @@ void rcutorture_get_gp_data(int *flags, unsigned long *gp_seq)
 EXPORT_SYMBOL_GPL(rcutorture_get_gp_data);
 
 /* Gather grace-period sequence numbers for rcutorture diagnostics. */
-unsigned long rcutorture_gather_gp_seqs(void)
+unsigned long long rcutorture_gather_gp_seqs(void)
 {
-	return ((READ_ONCE(rcu_state.gp_seq) & 0xff) << 16) |
-	       ((READ_ONCE(rcu_state.expedited_sequence) & 0xff) << 8) |
-	       (READ_ONCE(rcu_state.gp_seq_polled) & 0xff);
+	return ((READ_ONCE(rcu_state.gp_seq) & 0xffffULL) << 40) |
+	       ((READ_ONCE(rcu_state.expedited_sequence) & 0xffffffULL) << 16) |
+	       (READ_ONCE(rcu_state.gp_seq_polled) & 0xffffULL);
 }
 EXPORT_SYMBOL_GPL(rcutorture_gather_gp_seqs);
 
 /* Format grace-period sequence numbers for rcutorture diagnostics. */
-void rcutorture_format_gp_seqs(unsigned long seqs, char *cp)
+void rcutorture_format_gp_seqs(unsigned long long seqs, char *cp)
 {
-	unsigned int egp = (seqs >> 8) & 0xff;
-	unsigned int ggp = (seqs >> 16) & 0xff;
-	unsigned int pgp = seqs & 0xff;
+	unsigned int egp = (seqs >> 16) & 0xffffffULL;
+	unsigned int ggp = (seqs >> 40) & 0xffffULL;
+	unsigned int pgp = seqs & 0xffffULL;
 
-	snprintf(cp, 16, "g%02x:e%02x:p%02x", ggp, egp, pgp);
+	snprintf(cp, 20, "g%04x:e%06x:p%04x", ggp, egp, pgp);
 }
 EXPORT_SYMBOL_GPL(rcutorture_format_gp_seqs);