serial: replace open coded mutex with a real mutex in mrst_max3110.c
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 <arjan@linux.intel.com> Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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@ -56,8 +56,7 @@ struct uart_max3110 {
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wait_queue_head_t wq;
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struct task_struct *main_thread;
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struct task_struct *read_thread;
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int mthread_up;
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spinlock_t lock;
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struct mutex thread_mutex;;
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u32 baud;
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u16 cur_conf;
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@ -397,7 +396,8 @@ static int max3110_main_thread(void *_max)
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atomic_read(&max->con_tx_need) ||
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atomic_read(&max->uart_tx_need)) ||
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kthread_should_stop());
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max->mthread_up = 1;
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mutex_lock(&max->thread_mutex);
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#ifdef CONFIG_MRST_MAX3110_IRQ
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if (atomic_read(&max->irq_pending)) {
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@ -417,7 +417,7 @@ static int max3110_main_thread(void *_max)
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transmit_char(max);
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atomic_set(&max->uart_tx_need, 0);
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}
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max->mthread_up = 0;
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mutex_unlock(&max->thread_mutex);
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} while (!kthread_should_stop());
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return ret;
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@ -444,8 +444,9 @@ static int max3110_read_thread(void *_max)
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pr_info(PR_FMT "start read thread\n");
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do {
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if (!max->mthread_up)
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max3110_console_receive(max);
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mutex_lock(&max->thread_mutex);
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max3110_console_receive(max);
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mutex_unlock(&max->thread_mutex);
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set_current_state(TASK_INTERRUPTIBLE);
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schedule_timeout(HZ / 20);
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@ -745,7 +746,7 @@ static int serial_m3110_probe(struct spi_device *spi)
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max->name = spi->modalias; /* use spi name as the name */
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max->irq = (u16)spi->irq;
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spin_lock_init(&max->lock);
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mutex_init(&max->thread_mutex);
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max->word_7bits = 0;
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max->parity = 0;
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