From 7f2bf7840b74a160f908db83bc8829f8de10629b Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Sun, 9 Sep 2018 15:39:16 +1000 Subject: [PATCH] tty: hvc: hvc_write() fix break condition Commit 550ddadcc758 ("tty: hvc: hvc_write() may sleep") broke the termination condition in case the driver stops accepting characters. This can result in unnecessary polling of the busy driver. Restore it by testing the hvc_push return code. Tested-by: Matteo Croce Tested-by: Jason Gunthorpe Tested-by: Leon Romanovsky Signed-off-by: Nicholas Piggin Signed-off-by: Greg Kroah-Hartman --- drivers/tty/hvc/hvc_console.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index bacf9b73ec98..27284a2dcd2b 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c @@ -522,6 +522,8 @@ static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count return -EIO; while (count > 0) { + int ret = 0; + spin_lock_irqsave(&hp->lock, flags); rsize = hp->outbuf_size - hp->n_outbuf; @@ -537,10 +539,13 @@ static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count } if (hp->n_outbuf > 0) - hvc_push(hp); + ret = hvc_push(hp); spin_unlock_irqrestore(&hp->lock, flags); + if (!ret) + break; + if (count) { if (hp->n_outbuf > 0) hvc_flush(hp);