serial: sh-sci: Fix locking in sci_submit_rx()
Some callers of sci_submit_rx() hold the port spinlock, others don't. During fallback to PIO, the driver needs to obtain the port spinlock. If the lock was already held, spinlock recursion is detected, causing a deadlock: BUG: spinlock recursion on CPU#0. Fix this by adding a flag parameter to sci_submit_rx() for the caller to indicate the port spinlock is already held, so spinlock recursion can be avoided. Move the spin_lock_irqsave() up, so all DMA disable steps are protected, which is safe as the recently introduced dmaengine_terminate_async() can be called in atomic context. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Simon Horman <horms+renesas@verge.net.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -1331,7 +1331,7 @@ static void sci_tx_dma_release(struct sci_port *s)
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dma_release_channel(chan);
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}
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static void sci_submit_rx(struct sci_port *s)
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static void sci_submit_rx(struct sci_port *s, bool port_lock_held)
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{
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struct dma_chan *chan = s->chan_rx;
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struct uart_port *port = &s->port;
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@ -1362,16 +1362,18 @@ static void sci_submit_rx(struct sci_port *s)
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return;
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fail:
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/* Switch to PIO */
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if (!port_lock_held)
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spin_lock_irqsave(&port->lock, flags);
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if (i)
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dmaengine_terminate_async(chan);
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for (i = 0; i < 2; i++)
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s->cookie_rx[i] = -EINVAL;
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s->active_rx = -EINVAL;
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/* Switch to PIO */
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spin_lock_irqsave(&port->lock, flags);
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s->chan_rx = NULL;
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sci_start_rx(port);
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spin_unlock_irqrestore(&port->lock, flags);
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if (!port_lock_held)
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spin_unlock_irqrestore(&port->lock, flags);
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}
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static void work_fn_tx(struct work_struct *work)
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@ -1491,7 +1493,7 @@ static enum hrtimer_restart rx_timer_fn(struct hrtimer *t)
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}
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if (port->type == PORT_SCIFA || port->type == PORT_SCIFB)
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sci_submit_rx(s);
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sci_submit_rx(s, true);
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/* Direct new serial port interrupts back to CPU */
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scr = serial_port_in(port, SCSCR);
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@ -1617,7 +1619,7 @@ static void sci_request_dma(struct uart_port *port)
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s->chan_rx_saved = s->chan_rx = chan;
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if (port->type == PORT_SCIFA || port->type == PORT_SCIFB)
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sci_submit_rx(s);
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sci_submit_rx(s, false);
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}
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}
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@ -1667,7 +1669,7 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
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scr |= SCSCR_RDRQE;
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} else {
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scr &= ~SCSCR_RIE;
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sci_submit_rx(s);
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sci_submit_rx(s, false);
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}
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serial_port_out(port, SCSCR, scr);
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/* Clear current interrupt */
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