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serial: sh-sci: Fix locking in sci_submit_rx()

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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>
This commit is contained in:
Geert Uytterhoeven
2018-12-13 19:44:41 +01:00
committed by Greg Kroah-Hartman
parent 9c96f401e9
commit dd1f2250da
1 changed files with 9 additions and 7 deletions
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16
drivers/tty/serial/sh-sci.c
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@@ -1331,7 +1331,7 @@ static void sci_tx_dma_release(struct sci_port *s)
dma_release_channel(chan); dma_release_channel(chan);
} }
static void sci_submit_rx(struct sci_port *s) static void sci_submit_rx(struct sci_port *s, bool port_lock_held)
{ {
struct dma_chan *chan = s->chan_rx; struct dma_chan *chan = s->chan_rx;
struct uart_port *port = &s->port; struct uart_port *port = &s->port;
@@ -1362,16 +1362,18 @@ static void sci_submit_rx(struct sci_port *s)
return; return;
fail: fail:
/* Switch to PIO */
if (!port_lock_held)
spin_lock_irqsave(&port->lock, flags);
if (i) if (i)
dmaengine_terminate_async(chan); dmaengine_terminate_async(chan);
for (i = 0; i < 2; i++) for (i = 0; i < 2; i++)
s->cookie_rx[i] = -EINVAL; s->cookie_rx[i] = -EINVAL;
s->active_rx = -EINVAL; s->active_rx = -EINVAL;
/* Switch to PIO */
spin_lock_irqsave(&port->lock, flags);
s->chan_rx = NULL; s->chan_rx = NULL;
sci_start_rx(port); sci_start_rx(port);
spin_unlock_irqrestore(&port->lock, flags); if (!port_lock_held)
spin_unlock_irqrestore(&port->lock, flags);
} }
static void work_fn_tx(struct work_struct *work) static void work_fn_tx(struct work_struct *work)
@@ -1491,7 +1493,7 @@ static enum hrtimer_restart rx_timer_fn(struct hrtimer *t)
} }
if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) if (port->type == PORT_SCIFA || port->type == PORT_SCIFB)
sci_submit_rx(s); sci_submit_rx(s, true);
/* Direct new serial port interrupts back to CPU */ /* Direct new serial port interrupts back to CPU */
scr = serial_port_in(port, SCSCR); scr = serial_port_in(port, SCSCR);
@@ -1617,7 +1619,7 @@ static void sci_request_dma(struct uart_port *port)
s->chan_rx_saved = s->chan_rx = chan; s->chan_rx_saved = s->chan_rx = chan;
if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) if (port->type == PORT_SCIFA || port->type == PORT_SCIFB)
sci_submit_rx(s); sci_submit_rx(s, false);
} }
} }
@@ -1667,7 +1669,7 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
scr |= SCSCR_RDRQE; scr |= SCSCR_RDRQE;
} else { } else {
scr &= ~SCSCR_RIE; scr &= ~SCSCR_RIE;
sci_submit_rx(s); sci_submit_rx(s, false);
} }
serial_port_out(port, SCSCR, scr); serial_port_out(port, SCSCR, scr);
/* Clear current interrupt */ /* Clear current interrupt */