From: Takatoshi Akiyama <takatoshi.akiyama.kj@xxxxxxxxxxxxxxxxxxxxxxxx>
The SCSCR register access in sci_break_ctl() is not locked.
sci_start_tx() and sci_set_termios() changes the SCSCR register,
but does not lock sci_port.
Therefore, this patch adds lock during register access.
Also, remove the log output that leads to a double lock.
Some analysis of where locks are not taken is as follows.
It appears that the lock is not taken in:
- sci_start_tx(), sci_stop_tx() as this is installed as a callback.
And all callers of the callback take the lock.
- start_rx as callers take the lock.
- stop_rx. this is both installed as a callback and called directly.
In both cases the caller takes the lock.
Signed-off-by: Takatoshi Akiyama <takatoshi.akiyama.kj@xxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@xxxxxxxxxxx>
Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
---
v2 [Simon Horman]
* Also take lock around call to sci_start_rx() in sci_rx_dma_release()
* Enhanced changelog to describe where locks are not taken and why.
v1 [Takatoshi Akiyama]
This is a patch from the Gen3 3.3.2 BSP.
Geert, please consider it for mainline.
---
drivers/tty/serial/sh-sci.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index d5714deaaf92..d5e07ddae523 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1226,8 +1226,11 @@ static void sci_rx_dma_release(struct sci_port *s, bool enable_pio)
dma_free_coherent(chan->device->dev, s->buf_len_rx * 2, s->rx_buf[0],
sg_dma_address(&s->sg_rx[0]));
dma_release_channel(chan);
- if (enable_pio)
+ if (enable_pio) {
+ spin_lock_irqsave(&port->lock, flags);
sci_start_rx(port);
+ spin_unlock_irqrestore(&port->lock, flags);
+ }
}
static void sci_dma_rx_complete(void *arg)
@@ -1294,8 +1297,11 @@ static void sci_tx_dma_release(struct sci_port *s, bool enable_pio)
dma_unmap_single(chan->device->dev, s->tx_dma_addr, UART_XMIT_SIZE,
DMA_TO_DEVICE);
dma_release_channel(chan);
- if (enable_pio)
+ if (enable_pio) {
+ spin_lock_irqsave(&port->lock, flags);
sci_start_tx(port);
+ spin_unlock_irqrestore(&port->lock, flags);
+ }
}
static void sci_submit_rx(struct sci_port *s)
@@ -2004,6 +2010,7 @@ static void sci_enable_ms(struct uart_port *port)
static void sci_break_ctl(struct uart_port *port, int break_state)
{
unsigned short scscr, scsptr;
+ unsigned long flags;
/* check wheter the port has SCSPTR */
if (!sci_getreg(port, SCSPTR)->size) {
@@ -2014,6 +2021,7 @@ static void sci_break_ctl(struct uart_port *port, int break_state)
return;
}
+ spin_lock_irqsave(&port->lock, flags);
scsptr = serial_port_in(port, SCSPTR);
scscr = serial_port_in(port, SCSCR);
@@ -2027,6 +2035,7 @@ static void sci_break_ctl(struct uart_port *port, int break_state)
serial_port_out(port, SCSPTR, scsptr);
serial_port_out(port, SCSCR, scscr);
+ spin_unlock_irqrestore(&port->lock, flags);
}
static int sci_startup(struct uart_port *port)
@@ -2255,6 +2264,7 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
int min_err = INT_MAX, err;
unsigned long max_freq = 0;
int best_clk = -1;
+ unsigned long flags;
if ((termios->c_cflag & CSIZE) == CS7)
smr_val |= SCSMR_CHR;
@@ -2364,6 +2374,8 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
serial_port_out(port, SCCKS, sccks);
}
+ spin_lock_irqsave(&port->lock, flags);
+
sci_reset(port);
uart_update_timeout(port, termios->c_cflag, baud);
@@ -2381,9 +2393,6 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
case 27: smr_val |= SCSMR_SRC_27; break;
}
smr_val |= cks;
- dev_dbg(port->dev,
- "SCR 0x%x SMR 0x%x BRR %u CKS 0x%x DL %u SRR %u\n",
- scr_val, smr_val, brr, sccks, dl, srr);
serial_port_out(port, SCSCR, scr_val | s->hscif_tot);
serial_port_out(port, SCSMR, smr_val);
serial_port_out(port, SCBRR, brr);
@@ -2397,7 +2406,6 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
scr_val = s->cfg->scscr & (SCSCR_CKE1 | SCSCR_CKE0);
smr_val |= serial_port_in(port, SCSMR) &
(SCSMR_CKEDG | SCSMR_SRC_MASK | SCSMR_CKS);
- dev_dbg(port->dev, "SCR 0x%x SMR 0x%x\n", scr_val, smr_val);
serial_port_out(port, SCSCR, scr_val | s->hscif_tot);
serial_port_out(port, SCSMR, smr_val);
}
@@ -2434,7 +2442,6 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
scr_val |= SCSCR_RE | SCSCR_TE |
(s->cfg->scscr & ~(SCSCR_CKE1 | SCSCR_CKE0));
- dev_dbg(port->dev, "SCSCR 0x%x\n", scr_val);
serial_port_out(port, SCSCR, scr_val | s->hscif_tot);
if ((srr + 1 == 5) &&
(port->type == PORT_SCIFA || port->type == PORT_SCIFB)) {
@@ -2481,8 +2488,6 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
s->rx_frame = (100 * bits * HZ) / (baud / 10);
#ifdef CONFIG_SERIAL_SH_SCI_DMA
s->rx_timeout = DIV_ROUND_UP(s->buf_len_rx * 2 * s->rx_frame, 1000);
- dev_dbg(port->dev, "DMA Rx t-out %ums, tty t-out %u jiffies\n",
- s->rx_timeout * 1000 / HZ, port->timeout);
if (s->rx_timeout < msecs_to_jiffies(20))
s->rx_timeout = msecs_to_jiffies(20);
#endif
@@ -2490,6 +2495,8 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
if ((termios->c_cflag & CREAD) != 0)
sci_start_rx(port);
+ spin_unlock_irqrestore(&port->lock, flags);
+
sci_port_disable(s);
if (UART_ENABLE_MS(port, termios->c_cflag))
--
2.11.0
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