[PATCH AUTOSEL 4.19 162/258] serial: sh-sci: Fix locking in sci_submit_rx()
From: Sasha Levin <sashal@kernel.org>
Date: 2019-01-28 16:07:06
Also in:
lkml, stable
Subsystem:
the rest, tty layer and serial drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
From: Geert Uytterhoeven <geert+renesas@glider.be> [ 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 <redacted> 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 effba6ce0caa..5fdd7944b73b 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 */
--
2.19.1