From nobody Thu Sep 18 18:54:05 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 F0F1CC47088 for ; Sat, 3 Dec 2022 22:36:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229779AbiLCWgR (ORCPT ); Sat, 3 Dec 2022 17:36:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229481AbiLCWgP (ORCPT ); Sat, 3 Dec 2022 17:36:15 -0500 Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DEDA61A227; Sat, 3 Dec 2022 14:36:13 -0800 (PST) Received: from localhost.localdomain (unknown [46.242.14.200]) by mail.ispras.ru (Postfix) with ESMTPSA id 35B36419E9CF; Sat, 3 Dec 2022 22:36:12 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru 35B36419E9CF DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ispras.ru; s=default; t=1670106972; bh=KyNVm9MBPzirY+6lMswR9z1oVqviHj9cgAD/k3pwK+U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UVwCrIeUyn2OukzLX1DPgywIo16h+aUVH1DZjBuOxNn3rKHpmtDS9JDfN5ZI02plH 97saWnWE0eFcKIX2ZaNlcImnTA+SkWlBYY0llgvrHfleM8w4RPa0GqurhjMUGjijDJ VgVkX7tBnFv93wxV5G68Nz+ntcQxI5OrjV1Z7MeM= 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 5.19 1/2] Revert "tty: n_gsm: avoid call of sleeping functions from atomic context" Date: Sun, 4 Dec 2022 01:35:25 +0300 Message-Id: <20221203223526.11185-2-pchelkin@ispras.ru> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221203223526.11185-1-pchelkin@ispras.ru> References: <20221203223526.11185-1-pchelkin@ispras.ru> 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 132331c1f605eb5911795a6b9115114575594d0a. The above commit is reverted as the usage of tx_mutex seems not to solve the problem described in 132331c1f605 ("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 --- drivers/tty/n_gsm.c | 53 +++++++++++++++++++++++++-------------------- 1 file changed, 29 insertions(+), 24 deletions(-) diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 01c112e2e214..e23225aff5d9 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -248,7 +248,7 @@ struct gsm_mux { bool constipated; /* Asked by remote to shut up */ bool has_devices; /* Devices were registered */ =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 @@ -680,6 +680,7 @@ static int gsm_send(struct gsm_mux *gsm, int addr, int = cr, int control) struct gsm_msg *msg; u8 *dp; int ocr; + unsigned long flags; =20 msg =3D gsm_data_alloc(gsm, addr, 0, control); if (!msg) @@ -701,10 +702,10 @@ static int gsm_send(struct gsm_mux *gsm, int addr, in= t cr, int control) =20 gsm_print_packet("Q->", addr, cr, control, NULL, 0); =20 - mutex_lock(&gsm->tx_mutex); + spin_lock_irqsave(&gsm->tx_lock, flags); list_add_tail(&msg->list, &gsm->tx_ctrl_list); gsm->tx_bytes +=3D msg->len; - mutex_unlock(&gsm->tx_mutex); + spin_unlock_irqrestore(&gsm->tx_lock, flags); gsmld_write_trigger(gsm); =20 return 0; @@ -729,7 +730,7 @@ static void gsm_dlci_clear_queues(struct gsm_mux *gsm, = struct gsm_dlci *dlci) spin_unlock_irqrestore(&dlci->lock, flags); =20 /* Clear data packets in MUX write queue */ - mutex_lock(&gsm->tx_mutex); + spin_lock_irqsave(&gsm->tx_lock, flags); list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) { if (msg->addr !=3D addr) continue; @@ -737,7 +738,7 @@ static void gsm_dlci_clear_queues(struct gsm_mux *gsm, = struct gsm_dlci *dlci) list_del(&msg->list); kfree(msg); } - mutex_unlock(&gsm->tx_mutex); + spin_unlock_irqrestore(&gsm->tx_lock, flags); } =20 /** @@ -1023,9 +1024,10 @@ static void __gsm_data_queue(struct gsm_dlci *dlci, = struct gsm_msg *msg) =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 /** @@ -1037,7 +1039,7 @@ static void gsm_data_queue(struct gsm_dlci *dlci, str= uct 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) @@ -1097,7 +1099,7 @@ static int gsm_dlci_data_output(struct gsm_mux *gsm, = struct 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, @@ -1113,7 +1115,7 @@ 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) @@ -1167,7 +1169,7 @@ static int gsm_dlci_data_output_framed(struct gsm_mux= *gsm, * Push an empty frame in to the transmit queue to update the modem status * bits and to transmit an optional break. * - * Caller must hold the tx_mutex of the mux. + * Caller must hold the tx_lock of the mux. */ =20 static int gsm_dlci_modem_output(struct gsm_mux *gsm, struct gsm_dlci *dlc= i, @@ -1281,12 +1283,13 @@ static int 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) { @@ -1297,7 +1300,7 @@ 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 /* @@ -1991,13 +1994,14 @@ static void gsm_dlci_command(struct gsm_dlci *dlci,= const u8 *data, int len) static void gsm_kick_timeout(struct work_struct *work) { struct gsm_mux *gsm =3D container_of(work, struct gsm_mux, kick_timeout.w= ork); + unsigned long flags; int sent =3D 0; =20 - mutex_lock(&gsm->tx_mutex); + spin_lock_irqsave(&gsm->tx_lock, flags); /* If we have nothing running then we need to fire up */ if (gsm->tx_bytes < TX_THRESH_LO) sent =3D gsm_dlci_data_sweep(gsm); - mutex_unlock(&gsm->tx_mutex); + spin_unlock_irqrestore(&gsm->tx_lock, flags); =20 if (sent && debug & 4) pr_info("%s TX queue stalled\n", __func__); @@ -2527,7 +2531,6 @@ 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); @@ -2599,7 +2602,6 @@ 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_ctrl_list); INIT_LIST_HEAD(&gsm->tx_data_list); @@ -2608,6 +2610,7 @@ static struct gsm_mux *gsm_alloc_mux(void) INIT_WORK(&gsm->tx_work, gsmld_write_task); 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; @@ -2632,7 +2635,6 @@ 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); @@ -2788,16 +2790,17 @@ static void gsmld_write_trigger(struct gsm_mux *gsm) static void gsmld_write_task(struct work_struct *work) { struct gsm_mux *gsm =3D container_of(work, struct gsm_mux, tx_work); + unsigned long flags; int i, ret; =20 /* All outstanding control channel and control messages and one data * frame is sent. */ ret =3D -ENODEV; - mutex_lock(&gsm->tx_mutex); + spin_lock_irqsave(&gsm->tx_lock, flags); if (gsm->tty) ret =3D gsm_data_kick(gsm); - mutex_unlock(&gsm->tx_mutex); + spin_unlock_irqrestore(&gsm->tx_lock, flags); =20 if (ret >=3D 0) for (i =3D 0; i < NUM_DLCI; i++) @@ -3005,6 +3008,7 @@ 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 @@ -3012,13 +3016,13 @@ 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; } @@ -3315,13 +3319,14 @@ static struct tty_ldisc_ops tty_ldisc_packet =3D { static void gsm_modem_upd_via_data(struct gsm_dlci *dlci, u8 brk) { struct gsm_mux *gsm =3D dlci->gsm; + unsigned long flags; =20 if (dlci->state !=3D DLCI_OPEN || dlci->adaption !=3D 2) return; =20 - mutex_lock(&gsm->tx_mutex); + spin_lock_irqsave(&gsm->tx_lock, flags); gsm_dlci_modem_output(gsm, dlci, brk); - mutex_unlock(&gsm->tx_mutex); + spin_unlock_irqrestore(&gsm->tx_lock, flags); } =20 /** --=20 2.38.1