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serial: sh-sci: Fix race condition between RX worker and cleanup

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During serial port shutdown, the DMA receive worker function may still
be called after the receive DMA cleanup function has been called.
Fix this race condition between work_fn_rx() and sci_rx_dma_release() by
acquiring the port's spinlock in sci_rx_dma_release().
This requires releasing the spinlock in work_fn_rx() before calling (any
function that may call) sci_rx_dma_release().

Terminate all active receive DMA descriptors to release them, and to
make sure no more completions come in.

Do the same in sci_tx_dma_release() for symmetry, although the serial
upper layer will no longer submit more data at this point of time.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Geert Uytterhoeven 2015-08-21 20:02:50 +02:00 committed by Greg Kroah-Hartman
parent 0907c1004f
commit 04928b79d2
1 changed files with 14 additions and 5 deletions
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19
drivers/tty/serial/sh-sci.c
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@ -1362,9 +1362,13 @@ static void sci_rx_dma_release(struct sci_port *s, bool enable_pio)
{
struct dma_chan *chan = s->chan_rx;
struct uart_port *port = &s->port;
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
s->chan_rx = NULL;
s->cookie_rx[0] = s->cookie_rx[1] = -EINVAL;
spin_unlock_irqrestore(&port->lock, flags);
dmaengine_terminate_all(chan);
dma_free_coherent(chan->device->dev, s->buf_len_rx * 2,
sg_virt(&s->sg_rx[0]), sg_dma_address(&s->sg_rx[0]));
dma_release_channel(chan);
@ -1376,9 +1380,13 @@ static void sci_tx_dma_release(struct sci_port *s, bool enable_pio)
{
struct dma_chan *chan = s->chan_tx;
struct uart_port *port = &s->port;
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
s->chan_tx = NULL;
s->cookie_tx = -EINVAL;
spin_unlock_irqrestore(&port->lock, flags);
dmaengine_terminate_all(chan);
dma_unmap_single(chan->device->dev, s->tx_dma_addr, UART_XMIT_SIZE,
DMA_TO_DEVICE);
dma_release_channel(chan);
@ -1444,7 +1452,8 @@ static void work_fn_rx(struct work_struct *work)
} else {
dev_err(port->dev, "%s: Rx cookie %d not found!\n", __func__,
s->active_rx);
goto out;
spin_unlock_irqrestore(&port->lock, flags);
return;
}
status = dmaengine_tx_status(s->chan_rx, s->active_rx, &state);
@ -1464,9 +1473,10 @@ static void work_fn_rx(struct work_struct *work)
if (count)
tty_flip_buffer_push(&port->state->port);
sci_submit_rx(s);
spin_unlock_irqrestore(&port->lock, flags);
goto out;
sci_submit_rx(s);
return;
}
desc = dmaengine_prep_slave_sg(s->chan_rx, &s->sg_rx[new], 1,
@ -1485,14 +1495,13 @@ static void work_fn_rx(struct work_struct *work)
dev_dbg(port->dev, "%s: cookie %d #%d, new active cookie %d\n",
__func__, s->cookie_rx[new], new, s->active_rx);
out:
spin_unlock_irqrestore(&port->lock, flags);
return;
fail:
spin_unlock_irqrestore(&port->lock, flags);
dev_warn(port->dev, "Failed submitting Rx DMA descriptor\n");
sci_rx_dma_release(s, true);
spin_unlock_irqrestore(&port->lock, flags);
}
static void work_fn_tx(struct work_struct *work)