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authorGlauber Costa <glauber@scylladb.com>2020-01-30 11:00:13 -0500
committerJens Axboe <axboe@kernel.dk>2020-01-30 09:11:21 -0700
commitb20521873724fe8c61ada344baff752999ab960e (patch)
tree2eb81ca37a7270185d3510c50d34ed5f5cc59ae8
parent236570e08e3b406b3bd8143b3deea48c8b91fa2d (diff)
downloadliburing-b20521873724fe8c61ada344baff752999ab960e.tar.gz
liburing-b20521873724fe8c61ada344baff752999ab960e.tar.bz2
add helper functions to verify io_uring supported opcodes
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 probe is not available), and another one that given a probe checks if the opcode is supported. Signed-off-by: Glauber Costa <glauber@scylladb.com> CC: Avi Kivity <avi@scylladb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--src/include/liburing.h14
-rw-r--r--src/liburing.map1
-rw-r--r--src/setup.c19
3 files changed, 34 insertions, 0 deletions
diff --git a/src/include/liburing.h b/src/include/liburing.h
index 83d11dd..39db902 100644
--- a/src/include/liburing.h
+++ b/src/include/liburing.h
@@ -72,6 +72,20 @@ 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)
+{
+ if (op > p->last_op)
+ return 0;
+ return (p->ops[op].flags & IO_URING_OP_SUPPORTED) != 0;
+}
+
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;
+}