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serial: sc16is7xx: split into core and I2C/SPI parts (sc16is7xx_lines)

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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 registration.

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@hugovil.com/
Link: https://lore.kernel.org/all/CAHp75VebCZckUrNraYQj9k=Mrn2kbYs1Lx26f5-8rKJ3RXeh-w@mail.gmail.com/
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20240409154253.3043822-5-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Hugo Villeneuve
2024-04-09 11:42:52 -04:00
committed by Greg Kroah-Hartman
parent d492164381
commit cf9c37530f
1 changed files with 21 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/tty/serial/sc16is7xx.c
View File

@@ -10,12 +10,12 @@
#undef DEFAULT_SYMBOL_NAMESPACE
#define DEFAULT_SYMBOL_NAMESPACE SERIAL_NXP_SC16IS7XX
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/export.h>
#include <linux/gpio/driver.h>
#include <linux/idr.h>
#include <linux/kthread.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
@@ -345,7 +345,7 @@ 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,
@@ -1462,6 +1462,7 @@ 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]))
@@ -1526,13 +1527,19 @@ 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;
@@ -1578,7 +1585,7 @@ 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,
@@ -1636,9 +1643,12 @@ 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);
@@ -1661,7 +1671,7 @@ 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);
}