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serial: sc16is7xx: fix invalid sc16is7xx_lines bitfield in case of probe error 

If an error occurs during probing, the sc16is7xx_lines bitfield may be left
in a state that doesn't represent the correct state of lines allocation.

For example, in a system with two SC16 devices, if an error occurs only
during probing of channel (port) B of the second device, sc16is7xx_lines
final state will be 00001011b instead of the expected 00000011b.

This is caused in part because of the "i--" in the for/loop located in
the out_ports: error path.

Fix this by checking the return value of uart_add_one_port() and set line
allocation bit only if this was successful. This allows the refactor of
the obfuscated for(i--...) loop in the error path, and properly call
uart_remove_one_port() only when needed, and properly unset line allocation
bits.

Also use same mechanism in remove() when calling uart_remove_one_port().

Fixes: c64349722d ("sc16is7xx: support multiple devices")
Cc:  <stable@vger.kernel.org>
Cc: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20231221231823.2327894-2-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Hugo Villeneuve 2023-12-21 18:18:08 -05:00 committed by Greg Kroah-Hartman
parent 0c2a5f471c
commit 8a1060ce97
1 changed files with 18 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
drivers/tty/serial/sc16is7xx.c
View File

@ -407,19 +407,6 @@ static void sc16is7xx_port_update(struct uart_port *port, u8 reg,
regmap_update_bits(one->regmap, reg, mask, val);
}
static int sc16is7xx_alloc_line(void)
{
int i;
BUILD_BUG_ON(SC16IS7XX_MAX_DEVS > BITS_PER_LONG);
for (i = 0; i < SC16IS7XX_MAX_DEVS; i++)
if (!test_and_set_bit(i, &sc16is7xx_lines))
break;
return i;
}
static void sc16is7xx_power(struct uart_port *port, int on)
{
sc16is7xx_port_update(port, SC16IS7XX_IER_REG,
@ -1550,6 +1537,13 @@ static int sc16is7xx_probe(struct device *dev,
SC16IS7XX_IOCONTROL_SRESET_BIT);
for (i = 0; i < devtype->nr_uart; ++i) {
s->p[i].port.line = find_first_zero_bit(&sc16is7xx_lines,
SC16IS7XX_MAX_DEVS);
if (s->p[i].port.line >= SC16IS7XX_MAX_DEVS) {
ret = -ERANGE;
goto out_ports;
}
/* Initialize port data */
s->p[i].port.dev = dev;
s->p[i].port.irq = irq;
@ -1569,14 +1563,8 @@ static int sc16is7xx_probe(struct device *dev,
s->p[i].port.rs485_supported = sc16is7xx_rs485_supported;
s->p[i].port.ops = &sc16is7xx_ops;
s->p[i].old_mctrl = 0;
s->p[i].port.line = sc16is7xx_alloc_line();
s->p[i].regmap = regmaps[i];
if (s->p[i].port.line >= SC16IS7XX_MAX_DEVS) {
ret = -ENOMEM;
goto out_ports;
}
mutex_init(&s->p[i].efr_lock);
ret = uart_get_rs485_mode(&s->p[i].port);
@ -1594,8 +1582,13 @@ static int sc16is7xx_probe(struct device *dev,
kthread_init_work(&s->p[i].tx_work, sc16is7xx_tx_proc);
kthread_init_work(&s->p[i].reg_work, sc16is7xx_reg_proc);
kthread_init_delayed_work(&s->p[i].ms_work, sc16is7xx_ms_proc);
/* Register port */
uart_add_one_port(&sc16is7xx_uart, &s->p[i].port);
ret = uart_add_one_port(&sc16is7xx_uart, &s->p[i].port);
if (ret)
goto out_ports;
set_bit(s->p[i].port.line, &sc16is7xx_lines);
/* Enable EFR */
sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_LCR_REG,
@ -1653,10 +1646,9 @@ static int sc16is7xx_probe(struct device *dev,
#endif
out_ports:
for (i--; i >= 0; i--) {
uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port);
clear_bit(s->p[i].port.line, &sc16is7xx_lines);
}
for (i = 0; i < devtype->nr_uart; i++)
if (test_and_clear_bit(s->p[i].port.line, &sc16is7xx_lines))
uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port);
kthread_stop(s->kworker_task);
@ -1678,8 +1670,8 @@ static void sc16is7xx_remove(struct device *dev)
for (i = 0; i < s->devtype->nr_uart; i++) {
kthread_cancel_delayed_work_sync(&s->p[i].ms_work);
uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port);
clear_bit(s->p[i].port.line, &sc16is7xx_lines);
if (test_and_clear_bit(s->p[i].port.line, &sc16is7xx_lines))
uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port);
sc16is7xx_power(&s->p[i].port, 0);
}