Re: [PATCH net-next v3 2/3] vsock/test: Introduce get_transports()
From: Stefano Garzarella <sgarzare@redhat.com>
Date: 2025-06-17 14:12:17
Also in:
lkml, virtualization
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 <sgarzare@redhat.com>
Signed-off-by: Michal Luczaj <redacted>
---
tools/testing/vsock/util.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++
tools/testing/vsock/util.h | 29 ++++++++++++++++++++++++
2 files changed, 85 insertions(+)LGTM! Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
quoted hunk ↗ jump to hunk
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 <stefanha@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