Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'tty-4.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty fixes from Greg KH:
"Here are three small HVC tty driver fixes to resolve a reported
regression from 4.19-rc1.
All of these have been in linux-next for a while with no reported
issues"
* tag 'tty-4.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
tty: hvc: hvc_write() fix break condition
tty: hvc: hvc_poll() fix read loop batching
tty: hvc: hvc_poll() fix read loop hang
+33
-5
+33
-5
drivers/tty/hvc/hvc_console.c
+33
-5
drivers/tty/hvc/hvc_console.c
···
522
522
return -EIO;
523
523
524
524
while (count > 0) {
525
+
int ret = 0;
526
+
525
527
spin_lock_irqsave(&hp->lock, flags);
526
528
527
529
rsize = hp->outbuf_size - hp->n_outbuf;
···
539
537
}
540
538
541
539
if (hp->n_outbuf > 0)
542
-
hvc_push(hp);
540
+
ret = hvc_push(hp);
543
541
544
542
spin_unlock_irqrestore(&hp->lock, flags);
543
+
544
+
if (!ret)
545
+
break;
545
546
546
547
if (count) {
547
548
if (hp->n_outbuf > 0)
···
628
623
#define MAX_TIMEOUT (2000)
629
624
static u32 timeout = MIN_TIMEOUT;
630
625
626
+
/*
627
+
* Maximum number of bytes to get from the console driver if hvc_poll is
628
+
* called from driver (and can't sleep). Any more than this and we break
629
+
* and start polling with khvcd. This value was derived from from an OpenBMC
630
+
* console with the OPAL driver that results in about 0.25ms interrupts off
631
+
* latency.
632
+
*/
633
+
#define HVC_ATOMIC_READ_MAX 128
634
+
631
635
#define HVC_POLL_READ 0x00000001
632
636
#define HVC_POLL_WRITE 0x00000002
633
637
···
683
669
if (!hp->irq_requested)
684
670
poll_mask |= HVC_POLL_READ;
685
671
672
+
read_again:
686
673
/* Read data if any */
687
-
688
674
count = tty_buffer_request_room(&hp->port, N_INBUF);
689
675
690
676
/* If flip is full, just reschedule a later read */
···
731
717
#endif /* CONFIG_MAGIC_SYSRQ */
732
718
tty_insert_flip_char(&hp->port, buf[i], 0);
733
719
}
734
-
if (n == count)
735
-
poll_mask |= HVC_POLL_READ;
736
-
read_total = n;
720
+
read_total += n;
721
+
722
+
if (may_sleep) {
723
+
/* Keep going until the flip is full */
724
+
spin_unlock_irqrestore(&hp->lock, flags);
725
+
cond_resched();
726
+
spin_lock_irqsave(&hp->lock, flags);
727
+
goto read_again;
728
+
} else if (read_total < HVC_ATOMIC_READ_MAX) {
729
+
/* Break and defer if it's a large read in atomic */
730
+
goto read_again;
731
+
}
732
+
733
+
/*
734
+
* Latency break, schedule another poll immediately.
735
+
*/
736
+
poll_mask |= HVC_POLL_READ;
737
737
738
738
out:
739
739
/* Wakeup write queue if necessary */