From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Cox Subject: [PATCH 3/4] serial: replace open coded mutex with a real mutex in mrst_max3110.c Date: Thu, 17 Jun 2010 11:02:06 +0100 Message-ID: <20100617100204.4379.5286.stgit@localhost.localdomain> References: <20100617100012.4379.92949.stgit@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com ([192.55.52.93]:13046 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755395Ab0FQKZL (ORCPT ); Thu, 17 Jun 2010 06:25:11 -0400 In-Reply-To: <20100617100012.4379.92949.stgit@localhost.localdomain> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: greg@kroah.com, linux-serial@vger.kernel.org From: Arjan van de Ven The mrst_max3110.c driver uses an open coded, non atomic variable to create exclusion between two of its worker threads. More than that, while the main thread does a proper set-work-clear sequence, the other thread only does a test, with the result that no actual exclusion is happening. this patch replaces this open coded variable with a proper mutex in addition, the 'lock' spinlock is removed from the per adapter structure, the lock was only ever initialized but never used Signed-off-by: Arjan van de Ven Signed-off-by: Alan Cox --- drivers/serial/mrst_max3110.c | 15 ++++++++------- 1 files changed, 8 insertions(+), 7 deletions(-) diff --git a/drivers/serial/mrst_max3110.c b/drivers/serial/mrst_max3110.c index f9c01ae..0341853 100644 --- a/drivers/serial/mrst_max3110.c +++ b/drivers/serial/mrst_max3110.c @@ -56,8 +56,7 @@ struct uart_max3110 { wait_queue_head_t wq; struct task_struct *main_thread; struct task_struct *read_thread; - int mthread_up; - spinlock_t lock; + struct mutex thread_mutex;; u32 baud; u16 cur_conf; @@ -397,7 +396,8 @@ static int max3110_main_thread(void *_max) atomic_read(&max->con_tx_need) || atomic_read(&max->uart_tx_need)) || kthread_should_stop()); - max->mthread_up = 1; + + mutex_lock(&max->thread_mutex); #ifdef CONFIG_MRST_MAX3110_IRQ if (atomic_read(&max->irq_pending)) { @@ -417,7 +417,7 @@ static int max3110_main_thread(void *_max) transmit_char(max); atomic_set(&max->uart_tx_need, 0); } - max->mthread_up = 0; + mutex_unlock(&max->thread_mutex); } while (!kthread_should_stop()); return ret; @@ -444,8 +444,9 @@ static int max3110_read_thread(void *_max) pr_info(PR_FMT "start read thread\n"); do { - if (!max->mthread_up) - max3110_console_receive(max); + mutex_lock(&max->thread_mutex); + max3110_console_receive(max); + mutex_unlock(&max->thread_mutex); set_current_state(TASK_INTERRUPTIBLE); schedule_timeout(HZ / 20); @@ -745,7 +746,7 @@ static int serial_m3110_probe(struct spi_device *spi) max->name = spi->modalias; /* use spi name as the name */ max->irq = (u16)spi->irq; - spin_lock_init(&max->lock); + mutex_init(&max->thread_mutex); max->word_7bits = 0; max->parity = 0;