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[PATCH 2/2] Prevent vhost-user-blk-test hang
From: |
Raphael Norwitz |
Subject: |
[PATCH 2/2] Prevent vhost-user-blk-test hang |
Date: |
Fri, 27 Aug 2021 16:50:47 +0000 |
In the vhost-user-blk-test, as of now there is nothing stoping
vhost-user-blk in QEMU writing to the socket right after forking off the
storage daemon before it has a chance to come up properly, leaving the
test hanging forever. This intermittently hanging test has caused QEMU
automation failures reported multiple times on the mailing list [1].
This change makes the storage-daemon notify the vhost-user-blk-test
that it is fully initialized and ready to handle client connections via
a pipefd before allowing the test to proceed. This ensures that the
storage-daemon backend won't miss vhost-user messages and thereby
resolves the hang.
[1]
https://lore.kernel.org/qemu-devel/CAFEAcA8kYpz9LiPNxnWJAPSjc=nv532bEdyfynaBeMeohqBp3A@mail.gmail.com/
Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
---
tests/qtest/vhost-user-blk-test.c | 33 ++++++++++++++++++++++++++++---
1 file changed, 30 insertions(+), 3 deletions(-)
diff --git a/tests/qtest/vhost-user-blk-test.c
b/tests/qtest/vhost-user-blk-test.c
index 6f108a1b62..b62af449df 100644
--- a/tests/qtest/vhost-user-blk-test.c
+++ b/tests/qtest/vhost-user-blk-test.c
@@ -21,6 +21,8 @@
#include "libqos/vhost-user-blk.h"
#include "libqos/libqos-pc.h"
+const char *daemon_msg = "Block exports setup\n";
+
#define TEST_IMAGE_SIZE (64 * 1024 * 1024)
#define QVIRTIO_BLK_TIMEOUT_US (30 * 1000 * 1000)
#define PCI_SLOT_HP 0x06
@@ -885,7 +887,8 @@ static void start_vhost_user_blk(GString *cmd_line, int
vus_instances,
int num_queues)
{
const char *vhost_user_blk_bin = qtest_qemu_storage_daemon_binary();
- int i;
+ int i, err, pipe_fds[2];
+ char buf[32] = {0};
gchar *img_path;
GString *storage_daemon_command = g_string_new(NULL);
QemuStorageDaemonState *qsd;
@@ -898,6 +901,12 @@ static void start_vhost_user_blk(GString *cmd_line, int
vus_instances,
" -object memory-backend-memfd,id=mem,size=256M,share=on "
" -M memory-backend=mem -m 256M ");
+ err = pipe(pipe_fds);
+ if (err != 0) {
+ fprintf(stderr, "start_vhost_user_blk: pipe() failed %m\n");
+ abort();
+ }
+
for (i = 0; i < vus_instances; i++) {
int fd;
char *sock_path = create_listen_socket(&fd);
@@ -914,22 +923,40 @@ static void start_vhost_user_blk(GString *cmd_line, int
vus_instances,
i + 1, sock_path);
}
+ g_string_append_printf(storage_daemon_command, "--printset");
+
g_test_message("starting vhost-user backend: %s",
storage_daemon_command->str);
+
pid_t pid = fork();
if (pid == 0) {
+ close(pipe_fds[0]);
+
/*
* Close standard file descriptors so tap-driver.pl pipe detects when
* our parent terminates.
*/
close(0);
- close(1);
open("/dev/null", O_RDONLY);
- open("/dev/null", O_WRONLY);
+ close(1);
+ dup2(pipe_fds[1], 1);
execlp("/bin/sh", "sh", "-c", storage_daemon_command->str, NULL);
exit(1);
}
+
+ close(pipe_fds[1]);
+
+ err = read(pipe_fds[0], buf, 20);
+ if (err < 0) {
+ fprintf(stderr, "Failed to read from storage-daemon pipe %m\n");
+ abort();
+ } else if (strcmp(buf, daemon_msg) != 0) {
+ fprintf(stderr, "qemu-storage-daemon did not write expected messaage "
+ "to the pipe. Total bytes read: %d. Got: %s\n", err, buf);
+ abort();
+ }
+
g_string_free(storage_daemon_command, true);
qsd = g_new(QemuStorageDaemonState, 1);
--
2.20.1