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serial: bfin-uart: avoid dead lock in rx irq handler in smp kernel

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Disabing dma irq and lock bottom half in smp kernel doesn't ensure exclusive
uart access. Call spin_lock_irqsave() instead.

Signed-off-by: Steven Miao <realmz6@gmail.com>
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Steven Miao 2012-11-07 13:27:56 +08:00 committed by Greg Kroah-Hartman
parent 7a876b39b5
commit 9642dbe73c
1 changed files with 3 additions and 4 deletions
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7
drivers/tty/serial/bfin_uart.c
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@ -477,9 +477,9 @@ static void bfin_serial_dma_rx_chars(struct bfin_serial_port *uart)
void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart) void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
{ {
int x_pos, pos; int x_pos, pos;
unsigned long flags;
dma_disable_irq_nosync(uart->rx_dma_channel); spin_lock_irqsave(&uart->rx_lock, flags);
spin_lock_bh(&uart->rx_lock);
/* 2D DMA RX buffer ring is used. Because curr_y_count and /* 2D DMA RX buffer ring is used. Because curr_y_count and
* curr_x_count can't be read as an atomic operation, * curr_x_count can't be read as an atomic operation,
@ -510,8 +510,7 @@ void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
uart->rx_dma_buf.tail = uart->rx_dma_buf.head; uart->rx_dma_buf.tail = uart->rx_dma_buf.head;
} }
spin_unlock_bh(&uart->rx_lock); spin_unlock_irqrestore(&uart->rx_lock, flags);
dma_enable_irq(uart->rx_dma_channel);
mod_timer(&(uart->rx_dma_timer), jiffies + DMA_RX_FLUSH_JIFFIES); mod_timer(&(uart->rx_dma_timer), jiffies + DMA_RX_FLUSH_JIFFIES);
} }