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Re: [PATCH v4] Prevent vhost-user-blk-test hang
From: |
address@hidden |
Subject: |
Re: [PATCH v4] Prevent vhost-user-blk-test hang |
Date: |
Thu, 23 Sep 2021 16:22:21 -0500 |
User-agent: |
NeoMutt/20210205-773-8890a5 |
On Thu, Sep 23, 2021 at 03:16:17PM +0000, Raphael Norwitz wrote:
> 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 by
> creating a pidfile on initialiation. 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>
> ---
> Accidentally left a raw free() in v3. Converted it to g_free() here.
>
> tests/qtest/vhost-user-blk-test.c | 27 ++++++++++++++++++++++++++-
> 1 file changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/tests/qtest/vhost-user-blk-test.c
> b/tests/qtest/vhost-user-blk-test.c
> index 6f108a1b62..6898f55f11 100644
> --- a/tests/qtest/vhost-user-blk-test.c
> +++ b/tests/qtest/vhost-user-blk-test.c
> @@ -24,6 +24,7 @@
> #define TEST_IMAGE_SIZE (64 * 1024 * 1024)
> #define QVIRTIO_BLK_TIMEOUT_US (30 * 1000 * 1000)
> #define PCI_SLOT_HP 0x06
> +#define PIDFILE_RETRIES 5
>
> typedef struct {
> pid_t pid;
> @@ -885,7 +886,8 @@ 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, retries;
> + char *daemon_pidfile_path;
> gchar *img_path;
> GString *storage_daemon_command = g_string_new(NULL);
> QemuStorageDaemonState *qsd;
> @@ -898,6 +900,9 @@ 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 ");
>
> + daemon_pidfile_path = g_strdup_printf("/tmp/daemon-%d", getpid());
> + g_assert_cmpint((uintptr_t) daemon_pidfile_path, !=, (uintptr_t) NULL);
Feels verbose compared to:
g_assert(daemon_pidfile_path)
For that matter, can g_strdup_printf() ever return NULL? On memory
error, it exit()s rather than returning. So this assert feels like
overkill.
Otherwise,
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org