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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Sasha Levin <sashal@kernel.org>,
	jirislaby@kernel.org, ilpo.jarvinen@linux.intel.com,
	u.kleine-koenig@pengutronix.de, linux-serial@vger.kernel.org
Subject: [PATCH AUTOSEL 4.14 11/12] serial: cpm_uart: Avoid suspicious locking
Date: Fri,  8 Sep 2023 20:41:14 -0400	[thread overview]
Message-ID: <20230909004115.3581195-11-sashal@kernel.org> (raw)
In-Reply-To: <20230909004115.3581195-1-sashal@kernel.org>

From: Christophe Leroy <christophe.leroy@csgroup.eu>

[ Upstream commit 36ef11d311f405e55ad8e848c19b212ff71ef536 ]

  CHECK   drivers/tty/serial/cpm_uart/cpm_uart_core.c
drivers/tty/serial/cpm_uart/cpm_uart_core.c:1271:39: warning: context imbalance in 'cpm_uart_console_write' - unexpected unlock

Allthough 'nolock' is not expected to change, sparse find the following
form suspicious:

	if (unlikely(nolock)) {
		local_irq_save(flags);
	} else {
		spin_lock_irqsave(&pinfo->port.lock, flags);
	}

	cpm_uart_early_write(pinfo, s, count, true);

	if (unlikely(nolock)) {
		local_irq_restore(flags);
	} else {
		spin_unlock_irqrestore(&pinfo->port.lock, flags);
	}

Rewrite it a more obvious form:

	if (unlikely(oops_in_progress)) {
		local_irq_save(flags);
		cpm_uart_early_write(pinfo, s, count, true);
		local_irq_restore(flags);
	} else {
		spin_lock_irqsave(&pinfo->port.lock, flags);
		cpm_uart_early_write(pinfo, s, count, true);
		spin_unlock_irqrestore(&pinfo->port.lock, flags);
	}

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/f7da5cdc9287960185829cfef681a7d8614efa1f.1691068700.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/tty/serial/cpm_uart/cpm_uart_core.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/drivers/tty/serial/cpm_uart/cpm_uart_core.c b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
index 8f5a5a16cb3b2..f0af8a6de0aae 100644
--- a/drivers/tty/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
@@ -1283,19 +1283,14 @@ static void cpm_uart_console_write(struct console *co, const char *s,
 {
 	struct uart_cpm_port *pinfo = &cpm_uart_ports[co->index];
 	unsigned long flags;
-	int nolock = oops_in_progress;
 
-	if (unlikely(nolock)) {
+	if (unlikely(oops_in_progress)) {
 		local_irq_save(flags);
-	} else {
-		spin_lock_irqsave(&pinfo->port.lock, flags);
-	}
-
-	cpm_uart_early_write(pinfo, s, count, true);
-
-	if (unlikely(nolock)) {
+		cpm_uart_early_write(pinfo, s, count, true);
 		local_irq_restore(flags);
 	} else {
+		spin_lock_irqsave(&pinfo->port.lock, flags);
+		cpm_uart_early_write(pinfo, s, count, true);
 		spin_unlock_irqrestore(&pinfo->port.lock, flags);
 	}
 }
-- 
2.40.1


  parent reply	other threads:[~2023-09-09  0:45 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-09  0:41 [PATCH AUTOSEL 4.14 01/12] media: dvb-usb-v2: af9035: Fix null-ptr-deref in af9035_i2c_master_xfer Sasha Levin
2023-09-09  0:41 ` [PATCH AUTOSEL 4.14 02/12] media: dw2102: Fix null-ptr-deref in dw2102_i2c_transfer() Sasha Levin
2023-09-09  0:41 ` [PATCH AUTOSEL 4.14 03/12] media: af9005: Fix null-ptr-deref in af9005_i2c_xfer Sasha Levin
2023-09-09  0:41 ` [PATCH AUTOSEL 4.14 04/12] media: anysee: fix null-ptr-deref in anysee_master_xfer Sasha Levin
2023-09-09  0:41 ` [PATCH AUTOSEL 4.14 05/12] media: az6007: Fix null-ptr-deref in az6007_i2c_xfer() Sasha Levin
2023-09-09  0:41 ` [PATCH AUTOSEL 4.14 06/12] iio: core: Use min() instead of min_t() to make code more robust Sasha Levin
2023-09-10 13:23   ` Jonathan Cameron
2023-09-09  0:41 ` [PATCH AUTOSEL 4.14 07/12] media: tuners: qt1010: replace BUG_ON with a regular error Sasha Levin
2023-09-09  0:41 ` [PATCH AUTOSEL 4.14 08/12] media: pci: cx23885: replace BUG with error return Sasha Levin
2023-09-09  0:41 ` [PATCH AUTOSEL 4.14 09/12] usb: gadget: fsl_qe_udc: validate endpoint index for ch9 udc Sasha Levin
2023-09-09  0:41 ` [PATCH AUTOSEL 4.14 10/12] scsi: target: iscsi: Fix buffer overflow in lio_target_nacl_info_show() Sasha Levin
2023-09-09  0:41 ` Sasha Levin [this message]
2023-09-09  0:41 ` [PATCH AUTOSEL 4.14 12/12] kobject: Add sanity check for kset->kobj.ktype in kset_register() Sasha Levin

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