From nobody Thu Sep 18 17:20:38 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60ED4C47089 for ; Sat, 3 Dec 2022 21:56:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229736AbiLCVz7 (ORCPT ); Sat, 3 Dec 2022 16:55:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51406 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229542AbiLCVzw (ORCPT ); Sat, 3 Dec 2022 16:55:52 -0500 Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE72819C07; Sat, 3 Dec 2022 13:55:50 -0800 (PST) Received: from localhost.localdomain (unknown [46.242.14.200]) by mail.ispras.ru (Postfix) with ESMTPSA id 0934240D4004; Sat, 3 Dec 2022 21:55:47 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru 0934240D4004 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ispras.ru; s=default; t=1670104547; bh=fVJBaF1dCpZRburXtIqCzkusY3iGw92NB1GHXkxGjBw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WeD3MZ5qnAp+7hPSGCamxpYLmNBVa0lYUKsre0TkjsyfQnjbcsEkoCODogo90iOt1 mVznm5LO0IhLQs+Qb/cpm5g5Bxl28xxXHQCPvDN4Lma7UcS1/KOvbq8ruxB1BXkCVV uQVBf8E62rAh1GDNqoyrTgujpm8PvUWKg1gZQiCA= From: Fedor Pchelkin To: Greg Kroah-Hartman , stable@vger.kernel.org Cc: Fedor Pchelkin , linux-kernel@vger.kernel.org, Daniel Starke , jirislaby@kernel.org, Alexey Khoroshilov , lvc-project@linuxtesting.org, Pavel Machek Subject: [PATCH v2 5.10] Revert "tty: n_gsm: avoid call of sleeping functions from atomic context" Date: Sun, 4 Dec 2022 00:55:18 +0300 Message-Id: <20221203215518.8150-1-pchelkin@ispras.ru> X-Mailer: git-send-email 2.38.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Fedor Pchelkin [ Upstream commit acdab4cb4ba7e5f94d2b422ebd7bf4bf68178fb2 ] This reverts commit eb75efdec8dd0f01ac85c88feafa6e63b34a2521. The above commit is reverted as the usage of tx_mutex seems not to solve the problem described in eb75efdec8dd ("tty: n_gsm: avoid call of sleeping functions from atomic context") and just moves the bug to another place. Signed-off-by: Fedor Pchelkin Signed-off-by: Alexey Khoroshilov Reviewed-by: Daniel Starke Link: https://lore.kernel.org/r/20221008110221.13645-2-pchelkin@ispras.ru Signed-off-by: Greg Kroah-Hartman Reviewed-by: Pavel Machek --- v1->v2: added signed-off-by and reviewed-by drivers/tty/n_gsm.c | 39 +++++++++++++++++++++------------------ 1 file changed, 21 insertions(+), 18 deletions(-) diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index c91a3004931f..c2212f52a603 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -235,7 +235,7 @@ struct gsm_mux { int old_c_iflag; /* termios c_iflag value before attach */ bool constipated; /* Asked by remote to shut up */ =20 - struct mutex tx_mutex; + spinlock_t tx_lock; unsigned int tx_bytes; /* TX data outstanding */ #define TX_THRESH_HI 8192 #define TX_THRESH_LO 2048 @@ -820,14 +820,15 @@ static void __gsm_data_queue(struct gsm_dlci *dlci, s= truct gsm_msg *msg) * * Add data to the transmit queue and try and get stuff moving * out of the mux tty if not already doing so. Take the - * the gsm tx mutex and dlci lock. + * the gsm tx lock and dlci lock. */ =20 static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg) { - mutex_lock(&dlci->gsm->tx_mutex); + unsigned long flags; + spin_lock_irqsave(&dlci->gsm->tx_lock, flags); __gsm_data_queue(dlci, msg); - mutex_unlock(&dlci->gsm->tx_mutex); + spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags); } =20 /** @@ -839,7 +840,7 @@ static void gsm_data_queue(struct gsm_dlci *dlci, struc= t gsm_msg *msg) * is data. Keep to the MRU of the mux. This path handles the usual tty * interface which is a byte stream with optional modem data. * - * Caller must hold the tx_mutex of the mux. + * Caller must hold the tx_lock of the mux. */ =20 static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci) @@ -902,7 +903,7 @@ static int gsm_dlci_data_output(struct gsm_mux *gsm, st= ruct gsm_dlci *dlci) * is data. Keep to the MRU of the mux. This path handles framed data * queued as skbuffs to the DLCI. * - * Caller must hold the tx_mutex of the mux. + * Caller must hold the tx_lock of the mux. */ =20 static int gsm_dlci_data_output_framed(struct gsm_mux *gsm, @@ -918,7 +919,7 @@ static int gsm_dlci_data_output_framed(struct gsm_mux *= gsm, if (dlci->adaption =3D=3D 4) overhead =3D 1; =20 - /* dlci->skb is locked by tx_mutex */ + /* dlci->skb is locked by tx_lock */ if (dlci->skb =3D=3D NULL) { dlci->skb =3D skb_dequeue_tail(&dlci->skb_list); if (dlci->skb =3D=3D NULL) @@ -1018,12 +1019,13 @@ static void gsm_dlci_data_sweep(struct gsm_mux *gsm) =20 static void gsm_dlci_data_kick(struct gsm_dlci *dlci) { + unsigned long flags; int sweep; =20 if (dlci->constipated) return; =20 - mutex_lock(&dlci->gsm->tx_mutex); + spin_lock_irqsave(&dlci->gsm->tx_lock, flags); /* If we have nothing running then we need to fire up */ sweep =3D (dlci->gsm->tx_bytes < TX_THRESH_LO); if (dlci->gsm->tx_bytes =3D=3D 0) { @@ -1034,7 +1036,7 @@ static void gsm_dlci_data_kick(struct gsm_dlci *dlci) } if (sweep) gsm_dlci_data_sweep(dlci->gsm); - mutex_unlock(&dlci->gsm->tx_mutex); + spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags); } =20 /* @@ -1256,6 +1258,7 @@ static void gsm_control_message(struct gsm_mux *gsm, = unsigned int command, const u8 *data, int clen) { u8 buf[1]; + unsigned long flags; =20 switch (command) { case CMD_CLD: { @@ -1277,9 +1280,9 @@ static void gsm_control_message(struct gsm_mux *gsm, = unsigned int command, gsm->constipated =3D false; gsm_control_reply(gsm, CMD_FCON, NULL, 0); /* Kick the link in case it is idling */ - mutex_lock(&gsm->tx_mutex); + spin_lock_irqsave(&gsm->tx_lock, flags); gsm_data_kick(gsm, NULL); - mutex_unlock(&gsm->tx_mutex); + spin_unlock_irqrestore(&gsm->tx_lock, flags); break; case CMD_FCOFF: /* Modem wants us to STFU */ @@ -2225,7 +2228,6 @@ static void gsm_free_mux(struct gsm_mux *gsm) break; } } - mutex_destroy(&gsm->tx_mutex); mutex_destroy(&gsm->mutex); kfree(gsm->txframe); kfree(gsm->buf); @@ -2297,12 +2299,12 @@ static struct gsm_mux *gsm_alloc_mux(void) } spin_lock_init(&gsm->lock); mutex_init(&gsm->mutex); - mutex_init(&gsm->tx_mutex); kref_init(&gsm->ref); INIT_LIST_HEAD(&gsm->tx_list); timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0); init_waitqueue_head(&gsm->event); spin_lock_init(&gsm->control_lock); + spin_lock_init(&gsm->tx_lock); =20 gsm->t1 =3D T1; gsm->t2 =3D T2; @@ -2327,7 +2329,6 @@ static struct gsm_mux *gsm_alloc_mux(void) } spin_unlock(&gsm_mux_lock); if (i =3D=3D MAX_MUX) { - mutex_destroy(&gsm->tx_mutex); mutex_destroy(&gsm->mutex); kfree(gsm->txframe); kfree(gsm->buf); @@ -2652,15 +2653,16 @@ static int gsmld_open(struct tty_struct *tty) static void gsmld_write_wakeup(struct tty_struct *tty) { struct gsm_mux *gsm =3D tty->disc_data; + unsigned long flags; =20 /* Queue poll */ clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); - mutex_lock(&gsm->tx_mutex); + spin_lock_irqsave(&gsm->tx_lock, flags); gsm_data_kick(gsm, NULL); if (gsm->tx_bytes < TX_THRESH_LO) { gsm_dlci_data_sweep(gsm); } - mutex_unlock(&gsm->tx_mutex); + spin_unlock_irqrestore(&gsm->tx_lock, flags); } =20 /** @@ -2703,6 +2705,7 @@ static ssize_t gsmld_write(struct tty_struct *tty, st= ruct file *file, const unsigned char *buf, size_t nr) { struct gsm_mux *gsm =3D tty->disc_data; + unsigned long flags; int space; int ret; =20 @@ -2710,13 +2713,13 @@ static ssize_t gsmld_write(struct tty_struct *tty, = struct file *file, return -ENODEV; =20 ret =3D -ENOBUFS; - mutex_lock(&gsm->tx_mutex); + spin_lock_irqsave(&gsm->tx_lock, flags); space =3D tty_write_room(tty); if (space >=3D nr) ret =3D tty->ops->write(tty, buf, nr); else set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); - mutex_unlock(&gsm->tx_mutex); + spin_unlock_irqrestore(&gsm->tx_lock, flags); =20 return ret; } --=20 2.38.1