From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f194.google.com (mail-pl1-f194.google.com [209.85.214.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4252hT5QSjzF37D for ; Wed, 5 Sep 2018 22:15:05 +1000 (AEST) Received: by mail-pl1-f194.google.com with SMTP id s17-v6so3214326plp.7 for ; Wed, 05 Sep 2018 05:15:05 -0700 (PDT) From: Nicholas Piggin To: Greg Kroah-Hartman Cc: Nicholas Piggin , Jiri Slaby , Michael Ellerman , Matteo Croce , Jason Gunthorpe , Leon Romanovsky , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org (op) Subject: [PATCH 3/3] tty: hvc: hvc_write() fix break condition Date: Wed, 5 Sep 2018 22:14:39 +1000 Message-Id: <20180905121439.23809-4-npiggin@gmail.com> In-Reply-To: <20180905121439.23809-1-npiggin@gmail.com> References: <20180905121439.23809-1-npiggin@gmail.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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. Fixes: 550ddadcc758 ("tty: hvc: hvc_write() may sleep") Tested-by: Matteo Croce Tested-by: Leon Romanovsky Signed-off-by: Nicholas Piggin --- 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..c09a38fb0d66 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; + 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); -- 2.18.0