4.20-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit dd1f2250da95e87cb3e612858f94b14f99445a7c ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/sh-sci.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index cc56cb3b3eca..613007d7165e 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -1331,7 +1331,7 @@ static void sci_tx_dma_release(struct sci_port *s) 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 uart_port *port = &s->port; @@ -1362,16 +1362,18 @@ static void sci_submit_rx(struct sci_port *s) return;
fail: + /* Switch to PIO */ + if (!port_lock_held) + spin_lock_irqsave(&port->lock, flags); if (i) dmaengine_terminate_async(chan); for (i = 0; i < 2; i++) s->cookie_rx[i] = -EINVAL; s->active_rx = -EINVAL; - /* Switch to PIO */ - spin_lock_irqsave(&port->lock, flags); s->chan_rx = NULL; 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) @@ -1491,7 +1493,7 @@ static enum hrtimer_restart rx_timer_fn(struct hrtimer *t) }
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 */ 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;
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; } else { scr &= ~SCSCR_RIE; - sci_submit_rx(s); + sci_submit_rx(s, false); } serial_port_out(port, SCSCR, scr); /* Clear current interrupt */