From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: linux-next: Tree for Aug 1 Date: Tue, 1 Aug 2017 15:28:32 +0200 Message-ID: References: <20170801173746.6962444d@canb.auug.org.au> <20170801124204.GA457@jagdpanzerIV.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Sergey Senozhatsky Cc: Greg Kroah-Hartman , Linux-Next Mailing List , Linux Kernel Mailing List , Stephen Rothwell , Sergey Senozhatsky List-Id: linux-next.vger.kernel.org On Tue, Aug 1, 2017 at 3:20 PM, Arnd Bergmann wrote: > On Tue, Aug 1, 2017 at 2:42 PM, Sergey Senozhatsky > wrote: >> Hello, >> >> >> seems that commit 979990c6284814617 ("tty: improve tty_insert_flip_char() >> fast path") panics my kernel. >> >> in particular, this part > > Looking into it now, sorry for the breakage. Does this fix it? I definitely got this part wrong as I see now, we must look up the 'tail' after calling __tty_buffer_request_room, not before. Arnd diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index 6a8563633d4b..f8eba1c5412f 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -372,12 +372,13 @@ EXPORT_SYMBOL(tty_insert_flip_string_flags); */ int __tty_insert_flip_char(struct tty_port *port, unsigned char ch, char flag) { - struct tty_buffer *tb = port->buf.tail; + struct tty_buffer *tb; int flags = (flag == TTY_NORMAL) ? TTYB_NORMAL : 0; if (!__tty_buffer_request_room(port, 1, flags)) return 0; + tb = port->buf.tail; if (~tb->flags & TTYB_NORMAL) *flag_buf_ptr(tb, tb->used) = flag; *char_buf_ptr(tb, tb->used++) = ch;