add at24 driver

hc

2023-11-06 15ade055295d13f95d49e3d99b09f3bbfb4a43e7

 kernel/drivers/usb/gadget/function/u_serial.c
..
..
@@ -102,7 +102,6 @@
102
102
 
103
103
 	struct gserial		*port_usb;
104
104
 
105
-	bool			openclose;	/* open/close in progress */
106
105
 	u8			port_num;
107
106
 
108
107
 	struct list_head	read_pool;
..
..
@@ -595,81 +594,44 @@
595
594
 {
596
595
 	int		port_num = tty->index;
597
596
 	struct gs_port	*port;
598
-	int		status;
597
+	int		status = 0;
599
598
 
600
-	do {
601
-		mutex_lock(&ports[port_num].lock);
602
-		port = ports[port_num].port;
603
-		if (!port)
604
-			status = -ENODEV;
605
-		else {
606
-			spin_lock_irq(&port->port_lock);
599
+	mutex_lock(&ports[port_num].lock);
600
+	port = ports[port_num].port;
601
+	if (!port) {
602
+		status = -ENODEV;
603
+		goto out;
604
+	}
607
605
 
608
-			/* already open?  Great. */
609
-			if (port->port.count) {
610
-				status = 0;
611
-				port->port.count++;
612
-
613
-			/* currently opening/closing? wait ... */
614
-			} else if (port->openclose) {
615
-				status = -EBUSY;
616
-
617
-			/* ... else we do the work */
618
-			} else {
619
-				status = -EAGAIN;
620
-				port->openclose = true;
621
-			}
622
-			spin_unlock_irq(&port->port_lock);
623
-		}
624
-		mutex_unlock(&ports[port_num].lock);
625
-
626
-		switch (status) {
627
-		default:
628
-			/* fully handled */
629
-			return status;
630
-		case -EAGAIN:
631
-			/* must do the work */
632
-			break;
633
-		case -EBUSY:
634
-			/* wait for EAGAIN task to finish */
635
-			msleep(1);
636
-			/* REVISIT could have a waitchannel here, if
637
-			 * concurrent open performance is important
638
-			 */
639
-			break;
640
-		}
641
-	} while (status != -EAGAIN);
642
-
643
-	/* Do the "real open" */
644
606
 	spin_lock_irq(&port->port_lock);
645
607
 
646
608
 	/* allocate circular buffer on first open */
647
609
 	if (!kfifo_initialized(&port->port_write_buf)) {
648
610
 
649
611
 		spin_unlock_irq(&port->port_lock);
612
+
613
+		/*
614
+		 * portmaster's mutex still protects from simultaneous open(),
615
+		 * and close() can't happen, yet.
616
+		 */
617
+
650
618
 		status = kfifo_alloc(&port->port_write_buf,
651
619
 				     WRITE_BUF_SIZE, GFP_KERNEL);
652
-		spin_lock_irq(&port->port_lock);
653
-
654
620
 		if (status) {
655
621
 			pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
656
-				port->port_num, tty, file);
657
-			port->openclose = false;
658
-			goto exit_unlock_port;
622
+				 port_num, tty, file);
623
+			goto out;
659
624
 		}
625
+
626
+		spin_lock_irq(&port->port_lock);
660
627
 	}
661
628
 
662
-	/* REVISIT if REMOVED (ports[].port NULL), abort the open
663
-	 * to let rmmod work faster (but this way isn't wrong).
664
-	 */
665
-
666
-	/* REVISIT maybe wait for "carrier detect" */
629
+	/* already open?  Great. */
630
+	if (port->port.count++)
631
+		goto exit_unlock_port;
667
632
 
668
633
 	tty->driver_data = port;
669
634
 	port->port.tty = tty;
670
-
671
-	port->port.count = 1;
672
-	port->openclose = false;
673
635
 
674
636
 	/* if connected, start the I/O stream */
675
637
 	if (port->port_usb) {
..
..
@@ -684,20 +646,21 @@
684
646
 
685
647
 	pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
686
648
 
687
-	status = 0;
688
-
689
649
 exit_unlock_port:
690
650
 	spin_unlock_irq(&port->port_lock);
651
+out:
652
+	mutex_unlock(&ports[port_num].lock);
691
653
 	return status;
692
654
 }
693
655
 
694
-static int gs_writes_finished(struct gs_port *p)
656
+static int gs_close_flush_done(struct gs_port *p)
695
657
 {
696
658
 	int cond;
697
659
 
698
-	/* return true on disconnect or empty buffer */
660
+	/* return true on disconnect or empty buffer or if raced with open() */
699
661
 	spin_lock_irq(&p->port_lock);
700
-	cond = (p->port_usb == NULL) || !kfifo_len(&p->port_write_buf);
662
+	cond = p->port_usb == NULL || !kfifo_len(&p->port_write_buf) ||
663
+		p->port.count > 1;
701
664
 	spin_unlock_irq(&p->port_lock);
702
665
 
703
666
 	return cond;
..
..
@@ -711,6 +674,7 @@
711
674
 	spin_lock_irq(&port->port_lock);
712
675
 
713
676
 	if (port->port.count != 1) {
677
+raced_with_open:
714
678
 		if (port->port.count == 0)
715
679
 			WARN_ON(1);
716
680
 		else
..
..
@@ -719,12 +683,6 @@
719
683
 	}
720
684
 
721
685
 	pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
722
-
723
-	/* mark port as closing but in use; we can drop port lock
724
-	 * and sleep if necessary
725
-	 */
726
-	port->openclose = true;
727
-	port->port.count = 0;
728
686
 
729
687
 	gser = port->port_usb;
730
688
 	if (gser && gser->disconnect)
..
..
@@ -736,9 +694,13 @@
736
694
 	if (kfifo_len(&port->port_write_buf) > 0 && gser) {
737
695
 		spin_unlock_irq(&port->port_lock);
738
696
 		wait_event_interruptible_timeout(port->drain_wait,
739
-					gs_writes_finished(port),
697
+					gs_close_flush_done(port),
740
698
 					GS_CLOSE_TIMEOUT * HZ);
741
699
 		spin_lock_irq(&port->port_lock);
700
+
701
+		if (port->port.count != 1)
702
+			goto raced_with_open;
703
+
742
704
 		gser = port->port_usb;
743
705
 	}
744
706
 
..
..
@@ -751,9 +713,8 @@
751
713
 	else
752
714
 		kfifo_reset(&port->port_write_buf);
753
715
 
716
+	port->port.count = 0;
754
717
 	port->port.tty = NULL;
755
-
756
-	port->openclose = false;
757
718
 
758
719
 	pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
759
720
 			port->port_num, tty, file);
..
..
@@ -1181,8 +1142,9 @@
1181
1142
 	int cond;
1182
1143
 
1183
1144
 	spin_lock_irq(&port->port_lock);
1184
-	cond = (port->port.count == 0) && !port->openclose;
1145
+	cond = port->port.count == 0;
1185
1146
 	spin_unlock_irq(&port->port_lock);
1147
+
1186
1148
 	return cond;
1187
1149
 }
1188
1150
 
..
..
@@ -1375,7 +1337,7 @@
1375
1337
 
1376
1338
 	port->port_usb = NULL;
1377
1339
 	gser->ioport = NULL;
1378
-	if (port->port.count > 0 || port->openclose) {
1340
+	if (port->port.count > 0) {
1379
1341
 		wake_up_interruptible(&port->drain_wait);
1380
1342
 		if (port->port.tty)
1381
1343
 			tty_hangup(port->port.tty);
..
..
@@ -1388,7 +1350,7 @@
1388
1350
 
1389
1351
 	/* finally, free any unused/unusable I/O buffers */
1390
1352
 	spin_lock_irqsave(&port->port_lock, flags);
1391
-	if (port->port.count == 0 && !port->openclose)
1353
+	if (port->port.count == 0)
1392
1354
 		kfifo_free(&port->port_write_buf);
1393
1355
 	gs_free_requests(gser->out, &port->read_pool, NULL);
1394
1356
 	gs_free_requests(gser->out, &port->read_queue, NULL);