From nobody Wed Sep 17 06:23:27 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 021A4C4332F for ; Wed, 21 Dec 2022 19:58:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234704AbiLUT6P (ORCPT ); Wed, 21 Dec 2022 14:58:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47804 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229791AbiLUT6K (ORCPT ); Wed, 21 Dec 2022 14:58:10 -0500 Received: from msg-1.mailo.com (msg-1.mailo.com [213.182.54.11]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1832DBE26 for ; Wed, 21 Dec 2022 11:58:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=mailo.com; s=mailo; t=1671652671; bh=nWkOMj2N6LbgMIWdXK2PUNqVACe/YQOGQRAijbpfG8U=; h=X-EA-Auth:Date:From:To:Cc:Subject:Message-ID:MIME-Version: Content-Type; b=QBBgTrMGUYzx8uaXK8tFNt6L5lDBJm2U1zfKs4oxvTop2Hn5fovA+qFDXHrg/lNRa 2AkmhKJzgrHV9p/bWJG7UVEZSmlG6QclvXY/eAR09SegukunBHQW4nLYbCA+X7OJTX bjPrVVZfhl/gIuUoPK4+K32TxC7bpaT1mpZQscwQ= Received: by b-3.in.mailobj.net [192.168.90.13] with ESMTP via ip-206.mailobj.net [213.182.55.206] Wed, 21 Dec 2022 20:57:51 +0100 (CET) X-EA-Auth: mNmn2jbSxUm86SXJ/w4EMIdyTLjohVzgPtkuIMBB19SVH0DA7nC/5Kz50Q3wR8loEedLMRaz60iyZoiefapIVjMUBPLfeEHr Date: Thu, 22 Dec 2022 01:27:40 +0530 From: Deepak R Varma To: "Maciej W. Rozycki" , Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Saurabh Singh Sengar , Praveen Kumar , drv@mailo.com Subject: [PATCH] tty: serial: convert atomic_* to refcount_* APIs Message-ID: MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The refcount_* APIs are designed to address known issues with the atomic_t APIs for reference counting. They protect the reference counters from overflow/underflow, use-after-free errors, provide improved memory ordering guarantee schemes, are neater and safer. Hence, replace the atomic_* APIs by their equivalent refcount_t API functions. This patch proposal address the following warnings generated by the atomic_as_refcounter.cocci coccinelle script atomic_add_return(-1, ...) Signed-off-by: Deepak R Varma --- Note: The patch is compile tested using dec_station.defconfig for MIPS architecture. drivers/tty/serial/dz.c | 34 +++++++++++++--------------------- drivers/tty/serial/zs.c | 11 ++++------- drivers/tty/serial/zs.h | 2 +- 3 files changed, 18 insertions(+), 29 deletions(-) diff --git a/drivers/tty/serial/dz.c b/drivers/tty/serial/dz.c index 6b7ed7f2f3ca..c248201f9499 100644 --- a/drivers/tty/serial/dz.c +++ b/drivers/tty/serial/dz.c @@ -46,7 +46,7 @@ #include #include -#include +#include #include #include @@ -75,8 +75,8 @@ struct dz_port { struct dz_mux { struct dz_port dport[DZ_NB_PORT]; - atomic_t map_guard; - atomic_t irq_guard; + refcount_t map_guard; + refcount_t irq_guard; int initialised; }; @@ -399,18 +399,17 @@ static int dz_startup(struct uart_port *uport) struct dz_port *dport =3D to_dport(uport); struct dz_mux *mux =3D dport->mux; unsigned long flags; - int irq_guard; int ret; u16 tmp; - irq_guard =3D atomic_add_return(1, &mux->irq_guard); - if (irq_guard !=3D 1) + refcount_inc(&mux->irq_guard); + if (refcount_read(&mux->irq_guard) !=3D 1) return 0; ret =3D request_irq(dport->port.irq, dz_interrupt, IRQF_SHARED, "dz", mux); if (ret) { - atomic_add(-1, &mux->irq_guard); + refcount_dec(&mux->irq_guard); printk(KERN_ERR "dz: Cannot get IRQ %d!\n", dport->port.irq); return ret; } @@ -440,15 +439,13 @@ static void dz_shutdown(struct uart_port *uport) struct dz_port *dport =3D to_dport(uport); struct dz_mux *mux =3D dport->mux; unsigned long flags; - int irq_guard; u16 tmp; spin_lock_irqsave(&dport->port.lock, flags); dz_stop_tx(&dport->port); spin_unlock_irqrestore(&dport->port.lock, flags); - irq_guard =3D atomic_add_return(-1, &mux->irq_guard); - if (!irq_guard) { + if (refcount_dec_and_test(&mux->irq_guard)) { /* Disable interrupts. */ tmp =3D dz_in(dport, DZ_CSR); tmp &=3D ~(DZ_RIE | DZ_TIE); @@ -662,13 +659,11 @@ static const char *dz_type(struct uart_port *uport) static void dz_release_port(struct uart_port *uport) { struct dz_mux *mux =3D to_dport(uport)->mux; - int map_guard; iounmap(uport->membase); uport->membase =3D NULL; - map_guard =3D atomic_add_return(-1, &mux->map_guard); - if (!map_guard) + if (refcount_dec_and_test(&mux->map_guard)) release_mem_region(uport->mapbase, dec_kn_slot_size); } @@ -687,14 +682,12 @@ static int dz_map_port(struct uart_port *uport) static int dz_request_port(struct uart_port *uport) { struct dz_mux *mux =3D to_dport(uport)->mux; - int map_guard; int ret; - map_guard =3D atomic_add_return(1, &mux->map_guard); - if (map_guard =3D=3D 1) { - if (!request_mem_region(uport->mapbase, dec_kn_slot_size, - "dz")) { - atomic_add(-1, &mux->map_guard); + refcount_inc(&mux->map_guard); + if (refcount_read(&mux->map_guard) =3D=3D 1) { + if (!request_mem_region(uport->mapbase, dec_kn_slot_size, "dz")) { + refcount_dec(&mux->map_guard); printk(KERN_ERR "dz: Unable to reserve MMIO resource\n"); return -EBUSY; @@ -702,8 +695,7 @@ static int dz_request_port(struct uart_port *uport) } ret =3D dz_map_port(uport); if (ret) { - map_guard =3D atomic_add_return(-1, &mux->map_guard); - if (!map_guard) + if (refcount_dec_and_test(&mux->map_guard)) release_mem_region(uport->mapbase, dec_kn_slot_size); return ret; } diff --git a/drivers/tty/serial/zs.c b/drivers/tty/serial/zs.c index 730c648e32ff..6fa79705a0c9 100644 --- a/drivers/tty/serial/zs.c +++ b/drivers/tty/serial/zs.c @@ -753,15 +753,14 @@ static int zs_startup(struct uart_port *uport) struct zs_port *zport =3D to_zport(uport); struct zs_scc *scc =3D zport->scc; unsigned long flags; - int irq_guard; int ret; - irq_guard =3D atomic_add_return(1, &scc->irq_guard); - if (irq_guard =3D=3D 1) { + refcount_inc(&scc->irq_guard); + if (refcount_read(&scc->irq_guard) =3D=3D 1) { ret =3D request_irq(zport->port.irq, zs_interrupt, IRQF_SHARED, "scc", scc); if (ret) { - atomic_add(-1, &scc->irq_guard); + refcount_dec(&scc->irq_guard); printk(KERN_ERR "zs: can't get irq %d\n", zport->port.irq); return ret; @@ -806,7 +805,6 @@ static void zs_shutdown(struct uart_port *uport) struct zs_port *zport =3D to_zport(uport); struct zs_scc *scc =3D zport->scc; unsigned long flags; - int irq_guard; spin_lock_irqsave(&scc->zlock, flags); @@ -816,8 +814,7 @@ static void zs_shutdown(struct uart_port *uport) spin_unlock_irqrestore(&scc->zlock, flags); - irq_guard =3D atomic_add_return(-1, &scc->irq_guard); - if (!irq_guard) + if (refcount_dec_and_test(&scc->irq_guard)) free_irq(zport->port.irq, scc); } diff --git a/drivers/tty/serial/zs.h b/drivers/tty/serial/zs.h index 26ef8eafa1c1..bd97b73d7e16 100644 --- a/drivers/tty/serial/zs.h +++ b/drivers/tty/serial/zs.h @@ -40,7 +40,7 @@ struct zs_port { struct zs_scc { struct zs_port zport[2]; spinlock_t zlock; - atomic_t irq_guard; + refcount_t irq_guard; int initialised; }; -- 2.34.1