Change IORING_REGISTER_IOWQ_MAX_UNBOUND_WORKERS

This syncs with the kernel, it's now IORING_REGISTER_IOWQ_MAX_WORKERS
and can get/set the values for both bounded and unbounded workers.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

man/io_uring_register.2

@@ -320,23 +320,26 @@ set.
 Available since 5.14.
 
 .TP
-.B IORING_REGISTER_IOWQ_MAX_UNBOUND
+.B IORING_REGISTER_IOWQ_MAX_WORKERS
 By default, io_uring limits the unbounded workers created to the maximum
 processor count set by
-.I RLIMIT_NPROC.
-Sometimes this can be excessive, and this command provides a way to limit
-the count per ring (per NUMA node) instead.
+.I RLIMIT_NPROC
+and the bounded workers is a function of the SQ ring size and the number
+of CPUs in the system. Sometimes this can be excessive (or too little, for
+bounded), and this command provides a way to change the count per ring (per NUMA
+node) instead.
+
 .I arg
 must be set to an
 .I unsigned int
-pointer, with the value in the variable being set to the maximum count of
-unbounded workers per NUMA node. If the count being passed in is 0, then
-this command returns the current maximum values. If any other values is set,
-this command returns either the old value, or -1 and
-.I errno
-set appropriately.
+pointer to an array of two values, with the values in the array being set to
+the maximum count of workers per NUMA node. Index 0 holds the bounded worker
+count, and index 1 holds the unbounded worker count. On successful return, the
+passed in array will contain the previous maximum valyes for each type. If the
+count being passed in is 0, then this command returns the current maximum values
+and doesn't modify the current setting.
 .I nr_args
-must be set to 1, as the command only takes one argument.
+must be set to 2, as the command takes two values.
 
 Available since 5.15.
 

src/include/liburing.h

@@ -161,8 +161,8 @@ int __io_uring_sqring_wait(struct io_uring *ring);
 int io_uring_register_iowq_aff(struct io_uring *ring, size_t cpusz,
 				const cpu_set_t *mask);
 int io_uring_unregister_iowq_aff(struct io_uring *ring);
-int io_uring_unregister_iowq_max_unbound(struct io_uring *ring,
-					 unsigned int value);
+int io_uring_unregister_iowq_max_workers(struct io_uring *ring,
+					 unsigned int *values);
 
 /*
  * Helper for the peek/wait single cqe functions. Exported because of that,

src/liburing.map

@@ -42,5 +42,5 @@ LIBURING_2.1 {
 		io_uring_register_files_update_tag;
 		io_uring_register_iowq_aff;
 		io_uring_unregister_iowq_aff;
-		io_uring_register_iowq_max_unbound;
+		io_uring_register_iowq_max_workers;
 } LIBURING_2.0;

src/register.c

@@ -284,13 +284,13 @@ int io_uring_unregister_iowq_aff(struct io_uring *ring)
 	return ret;
 }
 
-int io_uring_register_iowq_max_unbound(struct io_uring *ring, unsigned int val)
+int io_uring_register_iowq_max_workers(struct io_uring *ring, unsigned int *val)
 {
 	int ret;
 
 	ret = __sys_io_uring_register(ring->ring_fd,
 					IORING_REGISTER_IOWQ_MAX_UNBOUND,
-					&val, 1);
+					val, 2);
 	if (ret < 0)
 		return -errno;