From: Hugo Villeneuve <[email protected]>
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/[email protected]/
Link: https://lore.kernel.org/all/CAHp75VebCZckUrNraYQj9k=Mrn2kbYs1Lx26f5-8rKJ3RXeh-w@mail.gmail.com/
Suggested-by: Andy Shevchenko <[email protected]>
Signed-off-by: Hugo Villeneuve <[email protected]>
---
drivers/tty/serial/sc16is7xx.c | 32 +++++++++++++++++++++-----------
1 file changed, 21 insertions(+), 11 deletions(-)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 51fb1c95d3826..1eb440f0c9cd0 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -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,
@@ -1472,6 +1472,7 @@ 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]))
@@ -1536,13 +1537,19 @@ 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;
@@ -1588,7 +1595,7 @@ 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,
@@ -1646,9 +1653,12 @@ 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);
@@ -1671,7 +1681,7 @@ 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