On 8/14/21 1:11 PM, Fabio M. De Francesco wrote:
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.
I haven't verified the use of the new API (yet) but I have a few comments on your patch, below. -Alex
Reported-by: kernel test robot <lkp@xxxxxxxxx> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx>
I'm not sure I'm right about this... But the actual change you're making has nothing to do with what the Intel test robot reported. I personally find the "Reported-by" here a little misleading, but maybe the "Link" line that gets added will provide explanation. Anyway, unless someone else contradicts/corrects me, I'd rather not have the "Reported-by" here (despite wanting to provide much credit to <lkp@xxxxxxxxx>...).
--- 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"
Please align the right-hand side of all three definitions here.
#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; +
Please do not add a blank line amid the local variable
definitions.
I'm not sure it checks for this, but you should run
your patch through "checkpatch.pl" before you send
it. E.g.:
./scripts/checkpatch.pl idr_to_xarray.patch
The error reported in the build of your first version
of this patch makes me think you might not have test-
built the code. I don't know if that's the case, but
(at least) building the code is expected before you
submit a patch for review.
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;
The caller of alloc_minor() (gb_uart_probe()) checks the return value, and if it's -ENOSPC it logs a device error indicating there are no remaining free device minor numbers. For xa_alloc() this is indicated by returning -EBUSY. Please update the caller to print the error message based on the updated error code.
+ 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[] = {
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