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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>
This commit is contained in:
Arjan van de Ven 2010-06-17 11:02:06 +01:00 committed by Greg Kroah-Hartman
parent 99dd3f6b7e
commit 68c16b4117
1 changed files with 8 additions and 7 deletions
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15
drivers/serial/mrst_max3110.c
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@ -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;