Convert greybus/uart.c from IDR to XArray. The abstract data type XArray is more memory-efficient, parallelisable, and cache friendly. It takes advantage of RCU to perform lookups without locking. Furthermore, IDR is deprecated because XArray has a better (cleaner and more consistent) API.

Reported-by: kernel test robot lkp@intel.com Signed-off-by: Fabio M. De Francesco fmdefrancesco@gmail.com ---

v1->v2: Fixed an issue found by the kernel test robot. It was due to passing to xa_*lock() the same old mutex that IDR used with the previous version of the code.

drivers/staging/greybus/uart.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c index 73f01ed1e5b7..5bf993e40f84 100644 --- a/drivers/staging/greybus/uart.c +++ b/drivers/staging/greybus/uart.c @@ -22,7 +22,7 @@ #include <linux/serial.h> #include <linux/tty_driver.h> #include <linux/tty_flip.h> -#include <linux/idr.h> +#include <linux/xarray.h> #include <linux/fs.h> #include <linux/kdev_t.h> #include <linux/kfifo.h> @@ -33,6 +33,7 @@ #include "gbphy.h"

#define GB_NUM_MINORS 16 /* 16 is more than enough */ +#define GB_RANGE_MINORS XA_LIMIT(0, GB_NUM_MINORS) #define GB_NAME "ttyGB"

#define GB_UART_WRITE_FIFO_SIZE PAGE_SIZE @@ -67,8 +68,7 @@ struct gb_tty { };

static struct tty_driver *gb_tty_driver; -static DEFINE_IDR(tty_minors); -static DEFINE_MUTEX(table_lock); +static DEFINE_XARRAY(tty_minors);

static int gb_uart_receive_data_handler(struct gb_operation *op) { @@ -77,6 +77,7 @@ static int gb_uart_receive_data_handler(struct gb_operation *op) struct tty_port *port = &gb_tty->port; struct gb_message *request = op->request; struct gb_uart_recv_data_request *receive_data; + u16 recv_data_size; int count; unsigned long tty_flags = TTY_NORMAL; @@ -341,8 +342,8 @@ static struct gb_tty *get_gb_by_minor(unsigned int minor) { struct gb_tty *gb_tty;

- mutex_lock(&table_lock); - gb_tty = idr_find(&tty_minors, minor); + xa_lock(&tty_minors); + gb_tty = xa_load(&tty_minors, minor); if (gb_tty) { mutex_lock(&gb_tty->mutex); if (gb_tty->disconnected) { @@ -353,19 +354,19 @@ static struct gb_tty *get_gb_by_minor(unsigned int minor) mutex_unlock(&gb_tty->mutex); } } - mutex_unlock(&table_lock); + xa_unlock(&tty_minors); return gb_tty; }

static int alloc_minor(struct gb_tty *gb_tty) { int minor; + int ret;

- mutex_lock(&table_lock); - minor = idr_alloc(&tty_minors, gb_tty, 0, GB_NUM_MINORS, GFP_KERNEL); - mutex_unlock(&table_lock); - if (minor >= 0) - gb_tty->minor = minor; + ret = xa_alloc(&tty_minors, &minor, gb_tty, GB_RANGE_MINORS, GFP_KERNEL); + if (ret) + return ret; + gb_tty->minor = minor; return minor; }

@@ -374,9 +375,7 @@ static void release_minor(struct gb_tty *gb_tty) int minor = gb_tty->minor;

gb_tty->minor = 0; /* Maybe should use an invalid value instead */ - mutex_lock(&table_lock); - idr_remove(&tty_minors, minor); - mutex_unlock(&table_lock); + xa_erase(&tty_minors, minor); }

static int gb_tty_install(struct tty_driver *driver, struct tty_struct *tty) @@ -982,7 +981,7 @@ static void gb_tty_exit(void) { tty_unregister_driver(gb_tty_driver); put_tty_driver(gb_tty_driver); - idr_destroy(&tty_minors); + xa_destroy(&tty_minors); }

static const struct gbphy_device_id gb_uart_id_table[] = {