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tty: hvc: hvc_poll() fix read loop hang

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Commit ec97eaad13 ("tty: hvc: hvc_poll() break hv read loop") causes
the virtio console to hang at times (e.g., if you paste a bunch of
characters to it.

The reason is that get_chars must return 0 before we can be sure the
driver will kick or poll input again, but this change only scheduled a
poll if get_chars had returned a full count. Change this to poll on
any > 0 count.

Reported-by: Matteo Croce <mcroce@redhat.com>
Reported-by: Jason Gunthorpe <jgg@mellanox.com>
Tested-by: Matteo Croce <mcroce@redhat.com>
Tested-by: Jason Gunthorpe <jgg@mellanox.com>
Tested-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicholas Piggin 2018-09-09 15:39:14 +10:00 committed by Greg Kroah-Hartman
parent 11da3a7f84
commit 6e7f6b82c6
1 changed files with 5 additions and 2 deletions
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7
drivers/tty/hvc/hvc_console.c
View file

@ -717,10 +717,13 @@ static int __hvc_poll(struct hvc_struct *hp, bool may_sleep)
#endif /* CONFIG_MAGIC_SYSRQ */
tty_insert_flip_char(&hp->port, buf[i], 0);
}
if (n == count)
poll_mask |= HVC_POLL_READ;
read_total = n;
/*
* Latency break, schedule another poll immediately.
*/
poll_mask |= HVC_POLL_READ;
out:
/* Wakeup write queue if necessary */
if (hp->do_wakeup) {