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[2620:137:e000::1:20]) by mx.google.com with ESMTP id g12-20020a63520c000000b00476a48051edsi17666323pgb.476.2022.11.23.10.29.17; Wed, 23 Nov 2022 10:29:30 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@ispras.ru header.s=default header.b=TUR+KFDw; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=ispras.ru Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239094AbiKWSUI (ORCPT + 99 others); Wed, 23 Nov 2022 13:20:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238892AbiKWST7 (ORCPT ); Wed, 23 Nov 2022 13:19:59 -0500 Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CAB36B85; Wed, 23 Nov 2022 10:19:57 -0800 (PST) Received: from fedor-dummypc.intra.ispras.ru (unknown [10.10.165.4]) by mail.ispras.ru (Postfix) with ESMTPSA id 9D6E740D4004; Wed, 23 Nov 2022 18:19:54 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru 9D6E740D4004 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ispras.ru; s=default; t=1669227594; bh=aEKfkaPDGkocbXhGsULGvnhKc/adpsBqQl1m77p2DtY=; h=From:To:Cc:Subject:Date:From; b=TUR+KFDwSSrC5Lz00os7h8xYFwgRwXlyeeBHazGTle6pns2oEz0wCkQRRJX6HmCma p/KWfKhfAcbIE59kFVIuDOI1B0tV7zQ72Iz5bDtFEZq4MRjLC1XSnibPQDqCKwB+ia /gSTUaoBrjZt4IIFmd9TbhdLjzO5tg1IlqsM8CkM= 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 Subject: [PATCH 5.10] Revert "tty: n_gsm: avoid call of sleeping functions from atomic context" Date: Wed, 23 Nov 2022 21:19:16 +0300 Message-Id: <20221123181916.6911-1-pchelkin@ispras.ru> X-Mailer: git-send-email 2.38.1 MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1750312598238571260?= X-GMAIL-MSGID: =?utf-8?q?1750312598238571260?= 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 Reviewed-by: Pavel Machek --- 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 */ - 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, struct 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. */ 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); } /** @@ -839,7 +840,7 @@ static void gsm_data_queue(struct gsm_dlci *dlci, struct 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. */ 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, 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. */ 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 == 4) overhead = 1; - /* dlci->skb is locked by tx_mutex */ + /* dlci->skb is locked by tx_lock */ if (dlci->skb == NULL) { dlci->skb = skb_dequeue_tail(&dlci->skb_list); if (dlci->skb == NULL) @@ -1018,12 +1019,13 @@ static void gsm_dlci_data_sweep(struct gsm_mux *gsm) static void gsm_dlci_data_kick(struct gsm_dlci *dlci) { + unsigned long flags; int sweep; if (dlci->constipated) return; - 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 = (dlci->gsm->tx_bytes < TX_THRESH_LO); if (dlci->gsm->tx_bytes == 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); } /* @@ -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; switch (command) { case CMD_CLD: { @@ -1277,9 +1280,9 @@ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command, gsm->constipated = 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); gsm->t1 = T1; gsm->t2 = T2; @@ -2327,7 +2329,6 @@ static struct gsm_mux *gsm_alloc_mux(void) } spin_unlock(&gsm_mux_lock); if (i == 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 = tty->disc_data; + unsigned long flags; /* 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); } /** @@ -2703,6 +2705,7 @@ static ssize_t gsmld_write(struct tty_struct *tty, struct file *file, const unsigned char *buf, size_t nr) { struct gsm_mux *gsm = tty->disc_data; + unsigned long flags; int space; int ret; @@ -2710,13 +2713,13 @@ static ssize_t gsmld_write(struct tty_struct *tty, struct file *file, return -ENODEV; ret = -ENOBUFS; - mutex_lock(&gsm->tx_mutex); + spin_lock_irqsave(&gsm->tx_lock, flags); space = tty_write_room(tty); if (space >= nr) ret = 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); return ret; }