From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx> Before, sc16is7xx_lines was checked for a free (zero) bit first, and then later it was set only if UART port registration succeeded. Now that sc16is7xx_lines is shared for the I2C and SPI drivers, there is a possibility that the two drivers can simultaneously try to reserve the same line bit at the same time. To prevent this, make sure line allocation is reserved atomically, and use a new variable to hold the status of UART port regisration. Now that we no longer need to search if a bit is set, it is now possible to simplify sc16is7xx_lines allocation by using the IDA framework. Link: https://lore.kernel.org/all/20231212150302.a9ec5d085a4ba65e89ca41af@xxxxxxxxxxx/ Link: https://lore.kernel.org/all/CAHp75VebCZckUrNraYQj9k=Mrn2kbYs1Lx26f5-8rKJ3RXeh-w@xxxxxxxxxxxxxx/ Suggested-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx> --- drivers/tty/serial/sc16is7xx.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index 05e5cbc0f9e8b..58ab6b16860b8 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -341,7 +341,7 @@ struct sc16is7xx_port { struct sc16is7xx_one p[]; }; -static DECLARE_BITMAP(sc16is7xx_lines, SC16IS7XX_MAX_DEVS); +static DEFINE_IDA(sc16is7xx_lines); static struct uart_driver sc16is7xx_uart = { .owner = THIS_MODULE, @@ -1468,6 +1468,7 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, u32 uartclk = 0; int i, ret; struct sc16is7xx_port *s; + bool port_registered[SC16IS7XX_MAX_PORTS]; for (i = 0; i < devtype->nr_uart; i++) if (IS_ERR(regmaps[i])) @@ -1532,13 +1533,19 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, regmap_write(regmaps[0], SC16IS7XX_IOCONTROL_REG, SC16IS7XX_IOCONTROL_SRESET_BIT); + /* Mark each port line and status as uninitialised. */ 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; + s->p[i].port.line = SC16IS7XX_MAX_DEVS; + port_registered[i] = false; + } + + for (i = 0; i < devtype->nr_uart; ++i) { + ret = ida_alloc_max(&sc16is7xx_lines, + SC16IS7XX_MAX_DEVS - 1, GFP_KERNEL); + if (ret < 0) goto out_ports; - } + + s->p[i].port.line = ret; /* Initialize port data */ s->p[i].port.dev = dev; @@ -1584,7 +1591,7 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, if (ret) goto out_ports; - set_bit(s->p[i].port.line, sc16is7xx_lines); + port_registered[i] = true; /* Enable EFR */ sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_LCR_REG, @@ -1642,9 +1649,12 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, #endif out_ports: - for (i = 0; i < devtype->nr_uart; i++) - if (test_and_clear_bit(s->p[i].port.line, sc16is7xx_lines)) + for (i = 0; i < devtype->nr_uart; i++) { + if (s->p[i].port.line < SC16IS7XX_MAX_DEVS) + ida_free(&sc16is7xx_lines, s->p[i].port.line); + if (port_registered[i]) uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port); + } kthread_stop(s->kworker_task); @@ -1667,7 +1677,7 @@ 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); - clear_bit(s->p[i].port.line, sc16is7xx_lines); + ida_free(&sc16is7xx_lines, s->p[i].port.line); uart_remove_one_port(&sc16is7xx_uart, &s->p[i].port); sc16is7xx_power(&s->p[i].port, 0); } -- 2.39.2
