treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

kernel/auditfilter.c

@@ -681,7 +681,7 @@ static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
 				data->values[i] = AUDIT_UID_UNSET;
 				break;
 			}
-			/* fall through - if set */
+			fallthrough;	/* if set */
 		default:
 			data->values[i] = f->val;
 		}

kernel/bpf/cgroup.c

@@ -1794,7 +1794,7 @@ static bool cg_sockopt_is_valid_access(int off, int size,
 			return prog->expected_attach_type ==
 				BPF_CGROUP_GETSOCKOPT;
 		case offsetof(struct bpf_sockopt, optname):
-			/* fallthrough */
+			fallthrough;
 		case offsetof(struct bpf_sockopt, level):
 			if (size != size_default)
 				return false;

kernel/bpf/cpumap.c

@@ -279,7 +279,7 @@ static int cpu_map_bpf_prog_run_xdp(struct bpf_cpu_map_entry *rcpu,
 			break;
 		default:
 			bpf_warn_invalid_xdp_action(act);
-			/* fallthrough */
+			fallthrough;
 		case XDP_DROP:
 			xdp_return_frame(xdpf);
 			stats->drop++;

kernel/bpf/syscall.c

@@ -2029,7 +2029,7 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
 	case BPF_PROG_TYPE_EXT:
 		if (expected_attach_type)
 			return -EINVAL;
-		/* fallthrough */
+		fallthrough;
 	default:
 		return 0;
 	}

kernel/bpf/verifier.c

@@ -5236,7 +5236,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
 				off_reg == dst_reg ? dst : src);
 			return -EACCES;
 		}
-		/* fall-through */
+		fallthrough;
 	default:
 		break;
 	}
@@ -10988,7 +10988,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 	default:
 		if (!prog_extension)
 			return -EINVAL;
-		/* fallthrough */
+		fallthrough;
 	case BPF_MODIFY_RETURN:
 	case BPF_LSM_MAC:
 	case BPF_TRACE_FENTRY:

kernel/capability.c

@@ -93,7 +93,7 @@ static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy)
 		break;
 	case _LINUX_CAPABILITY_VERSION_2:
 		warn_deprecated_v2();
-		/* fall through - v3 is otherwise equivalent to v2. */
+		fallthrough;	/* v3 is otherwise equivalent to v2 */
 	case _LINUX_CAPABILITY_VERSION_3:
 		*tocopy = _LINUX_CAPABILITY_U32S_3;
 		break;

kernel/compat.c

@@ -255,11 +255,11 @@ get_compat_sigset(sigset_t *set, const compat_sigset_t __user *compat)
 		return -EFAULT;
 	switch (_NSIG_WORDS) {
 	case 4: set->sig[3] = v.sig[6] | (((long)v.sig[7]) << 32 );
-		/* fall through */
+		fallthrough;
 	case 3: set->sig[2] = v.sig[4] | (((long)v.sig[5]) << 32 );
-		/* fall through */
+		fallthrough;
 	case 2: set->sig[1] = v.sig[2] | (((long)v.sig[3]) << 32 );
-		/* fall through */
+		fallthrough;
 	case 1: set->sig[0] = v.sig[0] | (((long)v.sig[1]) << 32 );
 	}
 #else

kernel/debug/gdbstub.c

@@ -1046,14 +1046,14 @@ int gdb_serial_stub(struct kgdb_state *ks)
 				return DBG_PASS_EVENT;
 			}
 #endif
-			/* Fall through */
+			fallthrough;
 		case 'C': /* Exception passing */
 			tmp = gdb_cmd_exception_pass(ks);
 			if (tmp > 0)
 				goto default_handle;
 			if (tmp == 0)
 				break;
-			/* Fall through - on tmp < 0 */
+			fallthrough;	/* on tmp < 0 */
 		case 'c': /* Continue packet */
 		case 's': /* Single step packet */
 			if (kgdb_contthread && kgdb_contthread != current) {
@@ -1062,7 +1062,7 @@ int gdb_serial_stub(struct kgdb_state *ks)
 				break;
 			}
 			dbg_activate_sw_breakpoints();
-			/* Fall through - to default processing */
+			fallthrough;	/* to default processing */
 		default:
 default_handle:
 			error = kgdb_arch_handle_exception(ks->ex_vector,

kernel/debug/kdb/kdb_keyboard.c

@@ -173,11 +173,11 @@ int kdb_get_kbd_char(void)
 	case KT_LATIN:
 		if (isprint(keychar))
 			break;		/* printable characters */
-		/* fall through */
+		fallthrough;
 	case KT_SPEC:
 		if (keychar == K_ENTER)
 			break;
-		/* fall through */
+		fallthrough;
 	default:
 		return -1;	/* ignore unprintables */
 	}

kernel/debug/kdb/kdb_support.c

@@ -432,7 +432,7 @@ int kdb_getphysword(unsigned long *word, unsigned long addr, size_t size)
 				*word = w8;
 			break;
 		}
-		/* fall through */
+		fallthrough;
 	default:
 		diag = KDB_BADWIDTH;
 		kdb_printf("kdb_getphysword: bad width %ld\n", (long) size);
@@ -481,7 +481,7 @@ int kdb_getword(unsigned long *word, unsigned long addr, size_t size)
 				*word = w8;
 			break;
 		}
-		/* fall through */
+		fallthrough;
 	default:
 		diag = KDB_BADWIDTH;
 		kdb_printf("kdb_getword: bad width %ld\n", (long) size);
@@ -525,7 +525,7 @@ int kdb_putword(unsigned long addr, unsigned long word, size_t size)
 			diag = kdb_putarea(addr, w8);
 			break;
 		}
-		/* fall through */
+		fallthrough;
 	default:
 		diag = KDB_BADWIDTH;
 		kdb_printf("kdb_putword: bad width %ld\n", (long) size);

kernel/events/core.c

@@ -10034,7 +10034,7 @@ perf_event_parse_addr_filter(struct perf_event *event, char *fstr,
 		case IF_SRC_KERNELADDR:
 		case IF_SRC_KERNEL:
 			kernel = 1;
-			/* fall through */
+			fallthrough;
 
 		case IF_SRC_FILEADDR:
 		case IF_SRC_FILE:

kernel/irq/handle.c

@@ -173,7 +173,7 @@ irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags
 
 			__irq_wake_thread(desc, action);
 
-			/* Fall through - to add to randomness */
+			fallthrough;	/* to add to randomness */
 		case IRQ_HANDLED:
 			*flags |= action->flags;
 			break;

kernel/irq/manage.c

@@ -271,7 +271,7 @@ int irq_do_set_affinity(struct irq_data *data, const struct cpumask *mask,
 	case IRQ_SET_MASK_OK:
 	case IRQ_SET_MASK_OK_DONE:
 		cpumask_copy(desc->irq_common_data.affinity, mask);
-		/* fall through */
+		fallthrough;
 	case IRQ_SET_MASK_OK_NOCOPY:
 		irq_validate_effective_affinity(data);
 		irq_set_thread_affinity(desc);
@@ -868,7 +868,7 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned long flags)
 	case IRQ_SET_MASK_OK_DONE:
 		irqd_clear(&desc->irq_data, IRQD_TRIGGER_MASK);
 		irqd_set(&desc->irq_data, flags);
-		/* fall through */
+		fallthrough;
 
 	case IRQ_SET_MASK_OK_NOCOPY:
 		flags = irqd_get_trigger_type(&desc->irq_data);

kernel/kallsyms.c

@@ -684,12 +684,12 @@ bool kallsyms_show_value(const struct cred *cred)
 	case 0:
 		if (kallsyms_for_perf())
 			return true;
-	/* fallthrough */
+		fallthrough;
 	case 1:
 		if (security_capable(cred, &init_user_ns, CAP_SYSLOG,
 				     CAP_OPT_NOAUDIT) == 0)
 			return true;
-	/* fallthrough */
+		fallthrough;
 	default:
 		return false;
 	}

kernel/power/hibernate.c

@@ -659,7 +659,7 @@ static void power_down(void)
 		break;
 	case HIBERNATION_PLATFORM:
 		hibernation_platform_enter();
-		/* Fall through */
+		fallthrough;
 	case HIBERNATION_SHUTDOWN:
 		if (pm_power_off)
 			kernel_power_off();

kernel/power/qos.c

@@ -119,7 +119,7 @@ int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
 		 * and add, then see if the aggregate has changed.
 		 */
 		plist_del(node, &c->list);
-		/* fall through */
+		fallthrough;
 	case PM_QOS_ADD_REQ:
 		plist_node_init(node, new_value);
 		plist_add(node, &c->list);
@@ -188,7 +188,7 @@ bool pm_qos_update_flags(struct pm_qos_flags *pqf,
 		break;
 	case PM_QOS_UPDATE_REQ:
 		pm_qos_flags_remove_req(pqf, req);
-		/* fall through */
+		fallthrough;
 	case PM_QOS_ADD_REQ:
 		req->flags = val;
 		INIT_LIST_HEAD(&req->node);

kernel/sched/core.c

@@ -2320,7 +2320,7 @@ static int select_fallback_rq(int cpu, struct task_struct *p)
 				state = possible;
 				break;
 			}
-			/* Fall-through */
+			fallthrough;
 		case possible:
 			do_set_cpus_allowed(p, cpu_possible_mask);
 			state = fail;

kernel/sched/topology.c

@@ -1219,13 +1219,13 @@ static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
 	case sa_rootdomain:
 		if (!atomic_read(&d->rd->refcount))
 			free_rootdomain(&d->rd->rcu);
-		/* Fall through */
+		fallthrough;
 	case sa_sd:
 		free_percpu(d->sd);
-		/* Fall through */
+		fallthrough;
 	case sa_sd_storage:
 		__sdt_free(cpu_map);
-		/* Fall through */
+		fallthrough;
 	case sa_none:
 		break;
 	}

kernel/signal.c

@@ -851,7 +851,7 @@ static int check_kill_permission(int sig, struct kernel_siginfo *info,
 			 */
 			if (!sid || sid == task_session(current))
 				break;
-			/* fall through */
+			fallthrough;
 		default:
 			return -EPERM;
 		}

kernel/sys.c

@@ -1753,7 +1753,7 @@ void getrusage(struct task_struct *p, int who, struct rusage *r)
 
 		if (who == RUSAGE_CHILDREN)
 			break;
-		/* fall through */
+		fallthrough;
 
 	case RUSAGE_SELF:
 		thread_group_cputime_adjusted(p, &tgutime, &tgstime);

kernel/time/hrtimer.c

@@ -377,7 +377,7 @@ static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
 	switch (state) {
 	case ODEBUG_STATE_ACTIVE:
 		WARN_ON(1);
-		/* fall through */
+		fallthrough;
 	default:
 		return false;
 	}

kernel/time/posix-timers.c

@@ -439,12 +439,12 @@ static struct pid *good_sigevent(sigevent_t * event)
 		rtn = pid_task(pid, PIDTYPE_PID);
 		if (!rtn || !same_thread_group(rtn, current))
 			return NULL;
-		/* FALLTHRU */
+		fallthrough;
 	case SIGEV_SIGNAL:
 	case SIGEV_THREAD:
 		if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX)
 			return NULL;
-		/* FALLTHRU */
+		fallthrough;
 	case SIGEV_NONE:
 		return pid;
 	default:

kernel/time/tick-broadcast.c

@@ -381,7 +381,7 @@ void tick_broadcast_control(enum tick_broadcast_mode mode)
 	switch (mode) {
 	case TICK_BROADCAST_FORCE:
 		tick_broadcast_forced = 1;
-		/* fall through */
+		fallthrough;
 	case TICK_BROADCAST_ON:
 		cpumask_set_cpu(cpu, tick_broadcast_on);
 		if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {

kernel/time/timer.c

@@ -666,7 +666,7 @@ static bool timer_fixup_activate(void *addr, enum debug_obj_state state)
 
 	case ODEBUG_STATE_ACTIVE:
 		WARN_ON(1);
-		/* fall through */
+		fallthrough;
 	default:
 		return false;
 	}

kernel/trace/blktrace.c

@@ -745,7 +745,7 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 #endif
 	case BLKTRACESTART:
 		start = 1;
-		/* fall through */
+		fallthrough;
 	case BLKTRACESTOP:
 		ret = __blk_trace_startstop(q, start);
 		break;

kernel/trace/trace_events_filter.c

@@ -499,7 +499,7 @@ predicate_parse(const char *str, int nr_parens, int nr_preds,
 					ptr++;
 					break;
 				}
-				/* fall through */
+				fallthrough;
 			default:
 				parse_error(pe, FILT_ERR_TOO_MANY_PREDS,
 					    next - str);
@@ -1273,7 +1273,7 @@ static int parse_pred(const char *str, void *data,
 		switch (op) {
 		case OP_NE:
 			pred->not = 1;
-			/* Fall through */
+			fallthrough;
 		case OP_GLOB:
 		case OP_EQ:
 			break;