It is common for an application using an ever-evolving interface to want to inquire about the presence of certain functionality it plans to use. Information about opcodes is stored in a io_uring_probe structure. There is usually some boilerplate involved in initializing one, and then using it to check if it is enabled. This patch adds two new helper functions: one that returns a pointer to a io_uring_probe (or null if it probe is not available), and another one that given a probe checks if the opcode is supported. Signed-off-by: Glauber Costa <glauber@xxxxxxxxxxxx> CC: Avi Kivity <avi@xxxxxxxxxxxx> --- src/include/liburing.h | 11 +++++++++++ src/liburing.map | 1 + src/setup.c | 19 +++++++++++++++++++ 3 files changed, 31 insertions(+) diff --git a/src/include/liburing.h b/src/include/liburing.h index 83d11dd..da52ca6 100644 --- a/src/include/liburing.h +++ b/src/include/liburing.h @@ -72,6 +72,17 @@ struct io_uring { /* * Library interface */ + +/* + * return an allocated io_uring_probe structure, or NULL if probe fails (for + * example, if it is not available). The caller is responsible for freeing it + */ +extern struct io_uring_probe *io_uring_get_probe(struct io_uring *ring); + +static inline int io_uring_opcode_supported(struct io_uring_probe *p, int op) { + return (p->last_op > op) && (p->ops[op].flags & IO_URING_OP_SUPPORTED); +} + extern int io_uring_queue_init_params(unsigned entries, struct io_uring *ring, struct io_uring_params *p); extern int io_uring_queue_init(unsigned entries, struct io_uring *ring, diff --git a/src/liburing.map b/src/liburing.map index b45f373..ac8288a 100644 --- a/src/liburing.map +++ b/src/liburing.map @@ -72,4 +72,5 @@ LIBURING_0.4 { io_uring_register_probe; io_uring_register_personality; io_uring_unregister_personality; + io_uring_get_probe; } LIBURING_0.3; diff --git a/src/setup.c b/src/setup.c index c53f234..c03274c 100644 --- a/src/setup.c +++ b/src/setup.c @@ -4,6 +4,7 @@ #include <unistd.h> #include <errno.h> #include <string.h> +#include <stdlib.h> #include "liburing/compat.h" #include "liburing/io_uring.h" @@ -167,3 +168,21 @@ void io_uring_queue_exit(struct io_uring *ring) io_uring_unmap_rings(sq, cq); close(ring->ring_fd); } + +struct io_uring_probe *io_uring_get_probe(struct io_uring *ring) +{ + struct io_uring_probe *probe; + int r; + + size_t len = sizeof(*probe) + 256 * sizeof(struct io_uring_probe_op); + probe = malloc(len); + memset(probe, 0, len); + r = io_uring_register_probe(ring, probe, 256); + if (r < 0) + goto fail; + + return probe; +fail: + free(probe); + return NULL; +} -- 2.20.1