From patchwork Fri Mar 5 12:21:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 395014 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39F77C433DB for ; Fri, 5 Mar 2021 12:33:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 11DBD65004 for ; Fri, 5 Mar 2021 12:33:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232196AbhCEMcu (ORCPT ); Fri, 5 Mar 2021 07:32:50 -0500 Received: from mail.kernel.org ([198.145.29.99]:42420 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232757AbhCEMcR (ORCPT ); Fri, 5 Mar 2021 07:32:17 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id DB25F65013; Fri, 5 Mar 2021 12:32:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614947537; bh=H8CyxCepIbQl8DhQ65JJffsh/LdxiqPj7i6TOIhOZes=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dTwelOKgxYOuWr1Gkrm73rZzeqcPXDR4hGDyAlwy73Cam4o2kY2nJCyca8Mp30gDw awnpvmcL98lK6O012FiAHWY0xLUhC2ACzVpH4Wlth3u2I+0AsQ+DIs4OE7YKWIIEJK TBgSEoKsK/o5tuXmoaytMmCVW44G+FcViqTaTJ6A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Linus Torvalds Subject: [PATCH 5.10 098/102] tty: teach the n_tty ICANON case about the new "cookie continuations" too Date: Fri, 5 Mar 2021 13:21:57 +0100 Message-Id: <20210305120908.101487980@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210305120903.276489876@linuxfoundation.org> References: <20210305120903.276489876@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Linus Torvalds commit d7fe75cbc23c7d225eee2ef04def239b6603dce7 upstream. The ICANON case is a bit messy, since it has to look for the line ending, and has special code to then suppress line ending characters if they match the __DISABLED_CHAR. So it actually looks up the line ending even past the point where it knows it won't copy it to the result buffer. That said, apart from all those odd legacy N_TTY ICANON cases, the actual "should we continue copying" logic isn't really all that complicated or different from the non-canon case. In fact, the lack of "wait for at least N characters" arguably makes the repeat case slightly simpler. It really just boils down to "there's more of the line to be copied". So add the necessarily trivial logic, and now the N_TTY case will give long result lines even when in canon mode. Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -2009,21 +2009,22 @@ static bool copy_from_read_buf(struct tt * read_tail published */ -static void canon_copy_from_read_buf(struct tty_struct *tty, +static bool canon_copy_from_read_buf(struct tty_struct *tty, unsigned char **kbp, size_t *nr) { struct n_tty_data *ldata = tty->disc_data; size_t n, size, more, c; size_t eol; - size_t tail; + size_t tail, canon_head; int found = 0; /* N.B. avoid overrun if nr == 0 */ if (!*nr) - return; + return false; - n = min(*nr + 1, smp_load_acquire(&ldata->canon_head) - ldata->read_tail); + canon_head = smp_load_acquire(&ldata->canon_head); + n = min(*nr + 1, canon_head - ldata->read_tail); tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1); size = min_t(size_t, tail + n, N_TTY_BUF_SIZE); @@ -2067,7 +2068,11 @@ static void canon_copy_from_read_buf(str else ldata->push = 0; tty_audit_push(); + return false; } + + /* No EOL found - do a continuation retry if there is more data */ + return ldata->read_tail != canon_head; } /** @@ -2138,8 +2143,13 @@ static ssize_t n_tty_read(struct tty_str * termios_rwsem, and can just continue to copy data. */ if (*cookie) { - if (copy_from_read_buf(tty, &kb, &nr)) - return kb - kbuf; + if (ldata->icanon && !L_EXTPROC(tty)) { + if (canon_copy_from_read_buf(tty, &kb, &nr)) + return kb - kbuf; + } else { + if (copy_from_read_buf(tty, &kb, &nr)) + return kb - kbuf; + } /* No more data - release locks and stop retries */ n_tty_kick_worker(tty); @@ -2236,7 +2246,8 @@ static ssize_t n_tty_read(struct tty_str } if (ldata->icanon && !L_EXTPROC(tty)) { - canon_copy_from_read_buf(tty, &kb, &nr); + if (canon_copy_from_read_buf(tty, &kb, &nr)) + goto more_to_be_read; } else { /* Deal with packet mode. */ if (packet && kb == kbuf) { @@ -2254,6 +2265,7 @@ static ssize_t n_tty_read(struct tty_str * will release them when done. */ if (copy_from_read_buf(tty, &kb, &nr) && kb - kbuf >= minimum) { +more_to_be_read: remove_wait_queue(&tty->read_wait, &wait); *cookie = cookie; return kb - kbuf;