Hi Michal,
On Wed, Jun 11, 2025 at 09:56:51PM +0200, Michal Luczaj wrote:
Return a bitmap of registered vsock transports. As guesstimated by
grepping
/proc/kallsyms (CONFIG_KALLSYMS=y) for known symbols of type `struct
vsock_transport`, or `struct virtio_transport` in case the
vsock_transport
is embedded within.
Note that the way `enum transport` and `transport_ksyms[]` are defined
triggers checkpatch.pl:
util.h:11: ERROR: Macros with complex values should be enclosed in
parentheses
util.h:20: ERROR: Macros with complex values should be enclosed in
parentheses
util.h:20: WARNING: Argument 'symbol' is not used in function-like
macro
util.h:28: WARNING: Argument 'name' is not used in function-like macro
While commit 15d4734c7a58 ("checkpatch: qualify do-while-0 advice")
suggests it is known that the ERRORs heuristics are insufficient, I can
not
find many other places where preprocessor is used in this
checkpatch-unhappy fashion. Notable exception being bcachefs, e.g.
fs/bcachefs/alloc_background_format.h. WARNINGs regarding unused macro
arguments seem more common, e.g. __ASM_SEL in
arch/x86/include/asm/asm.h.
In other words, this might be unnecessarily complex. The same can be
achieved by just telling human to keep the order:
enum transport {
TRANSPORT_LOOPBACK = BIT(0),
TRANSPORT_VIRTIO = BIT(1),
TRANSPORT_VHOST = BIT(2),
TRANSPORT_VMCI = BIT(3),
TRANSPORT_HYPERV = BIT(4),
TRANSPORT_NUM = 5,
};
#define KSYM_ENTRY(sym) "d " sym "_transport"
/* Keep `enum transport` order */
static const char * const transport_ksyms[] = {
KSYM_ENTRY("loopback"),
KSYM_ENTRY("virtio"),
KSYM_ENTRY("vhost"),
KSYM_ENTRY("vmci"),
KSYM_ENTRY("vhs"),
};
Suggested-by: Stefano Garzarella <sgarz...@redhat.com>
Signed-off-by: Michal Luczaj <m...@rbox.co>
---
tools/testing/vsock/util.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++
tools/testing/vsock/util.h | 29 ++++++++++++++++++++++++
2 files changed, 85 insertions(+)
diff --git a/tools/testing/vsock/util.c b/tools/testing/vsock/util.c
index
b7b3fb2221c1682ecde58cf12e2f0b0ded1cff39..803f1e075b62228c25f9dffa1eff131b8072a06a
100644
--- a/tools/testing/vsock/util.c
+++ b/tools/testing/vsock/util.c
@@ -7,6 +7,7 @@
* Author: Stefan Hajnoczi <stefa...@redhat.com>
*/
+#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdint.h>
@@ -23,6 +24,9 @@
#include "control.h"
#include "util.h"
+#define KALLSYMS_PATH "/proc/kallsyms"
+#define KALLSYMS_LINE_LEN 512
+
/* Install signal handlers */
void init_signals(void)
{
@@ -854,3 +858,55 @@ void enable_so_linger(int fd, int timeout)
exit(EXIT_FAILURE);
}
}
+
+static int __get_transports(void)
+{
+ char buf[KALLSYMS_LINE_LEN];
+ const char *ksym;
+ int ret = 0;
+ FILE *f;
+
+ f = fopen(KALLSYMS_PATH, "r");
+ if (!f) {
+ perror("Can't open " KALLSYMS_PATH);
+ exit(EXIT_FAILURE);
+ }
+
+ while (fgets(buf, sizeof(buf), f)) {
+ char *match;
+ int i;
+
+ assert(buf[strlen(buf) - 1] == '\n');
+
+ for (i = 0; i < TRANSPORT_NUM; ++i) {
+ if (ret & BIT(i))
+ continue;
+
+ /* Match should be followed by '\t' or '\n'.
+ * See kallsyms.c:s_show().
+ */
+ ksym = transport_ksyms[i];
+ match = strstr(buf, ksym);
+ if (match && isspace(match[strlen(ksym)])) {
+ ret |= BIT(i);
+ break;
+ }
+ }
+ }
+
+ fclose(f);
+ return ret;
+}
+
+/* Return integer with TRANSPORT_* bit set for every (known) registered vsock
+ * transport.
+ */
+int get_transports(void)
+{
+ static int tr = -1;
+
+ if (tr == -1)
+ tr = __get_transports();
+
+ return tr;
+}
diff --git a/tools/testing/vsock/util.h b/tools/testing/vsock/util.h
index
0afe7cbae12e5194172c639ccfbeb8b81f7c25ac..71895192cc02313bf52784e2f77aa3b0c28a0c94
100644
--- a/tools/testing/vsock/util.h
+++ b/tools/testing/vsock/util.h
@@ -3,8 +3,36 @@
#define UTIL_H
#include <sys/socket.h>
+#include <linux/bitops.h>
+#include <linux/kernel.h>
#include <linux/vm_sockets.h>
+/* All known vsock transports, see callers of vsock_core_register() */
+#define KNOWN_TRANSPORTS(x) \
+ x(LOOPBACK, "loopback") \
+ x(VIRTIO, "virtio") \
+ x(VHOST, "vhost") \
+ x(VMCI, "vmci") \
+ x(HYPERV, "hvs")
+
+enum transport {
+ TRANSPORT_COUNTER_BASE = __COUNTER__ + 1,
+ #define x(name, symbol) \
+ TRANSPORT_##name = BIT(__COUNTER__ - TRANSPORT_COUNTER_BASE),
+ KNOWN_TRANSPORTS(x)
+ TRANSPORT_NUM = __COUNTER__ - TRANSPORT_COUNTER_BASE,
+ #undef x
+};
+
+static const char * const transport_ksyms[] = {
+ #define x(name, symbol) "d " symbol "_transport",
+ KNOWN_TRANSPORTS(x)
+ #undef x
+};
+
+static_assert(ARRAY_SIZE(transport_ksyms) == TRANSPORT_NUM);
+static_assert(BITS_PER_TYPE(int) >= TRANSPORT_NUM);
+
/* Tests can either run as the client or the server */
enum test_mode {
TEST_MODE_UNSET,
@@ -82,4 +110,5 @@ void setsockopt_timeval_check(int fd, int level, int optname,
struct timeval val, char const *errmsg);
void enable_so_zerocopy_check(int fd);
void enable_so_linger(int fd, int timeout);
+int get_transports(void);
#endif /* UTIL_H */
--
2.49.0
Checked the code and tested `get_transports()`. It works as expected!
I'm not sure about the `checkpatch.pl` errors, but code LGTM to me.
Tested-by: Luigi Leonardi <leona...@redhat.com>
Reviewed-by: Luigi Leonardi <leona...@redhat.com>
Thanks!
Luigi
