On 7/28/21 10:17 AM, Andrew Melnychenko wrote:
> New function to call "qemu-ebpf-rss-helper".
> The helper passes few fds through unix socket.
> Technically libvirt should not be aware how many and what those fds.
> The helper should return fds that should be passed to the qemu as is and in same order.
>
> Signed-off-by: Andrew Melnychenko <andrew@xxxxxxxxxx>
> ---
> src/qemu/qemu_interface.c | 54 +++++++++++++++++++++++++++++++++++++++
> src/qemu/qemu_interface.h | 2 ++
> 2 files changed, 56 insertions(+)
>
> diff --git a/src/qemu/qemu_interface.c b/src/qemu/qemu_interface.c
> index ac0168c80d..76435af94e 100644
> --- a/src/qemu/qemu_interface.c
> +++ b/src/qemu/qemu_interface.c
> @@ -777,3 +777,57 @@ qemuInterfaceOpenVhostNet(virDomainDef *def,
>
> return -1;
> }
> +
> +
> +int qemuEbpfRssHelper(const char *helper, int *fds, int nfds)
> +{
> + int ret = 0;
> + int err = 0;
> + int unix_fds[2] = { -1, -1 };
> + virCommand *cmd = NULL;
If you'd use:
g_autoptr(virCommand) cmd = NULL;
then you can ditch that explicit virCommandFree() call below.
> +
> + if (!helper || !fds || !nfds) {
> + return -1;
> + }
> +
> + ret = socketpair(AF_UNIX, SOCK_STREAM, 0, unix_fds);
> + if (ret) {
> + virReportSystemError(errno, "%s", _("failed to create socket"));
> + return -1;
> + }
> +
> + cmd = virCommandNew(helper);
> + if (cmd == NULL) {
This can't really happen. Also, all virCommand* APIs are prepared for
this situation so that we can write simpler code:
cmd = virCommandNew();
virCommandSomething(cmd);
virCommandSomethingElse(cmd);
if (virCommandRunAsync(cmd) < 0) /* This is the point where we learn
about any previous error */
> + VIR_FORCE_CLOSE(unix_fds[1]);
> + ret = -1;
> + goto cleanup;
> + }
> + virCommandAddArgFormat(cmd, "--fd=%d", unix_fds[1]);
> + virCommandPassFD(cmd, unix_fds[1], VIR_COMMAND_PASS_FD_CLOSE_PARENT);
> + virCommandDoAsyncIO(cmd);
> +
> + if (virCommandRunAsync(cmd, NULL) < 0) {
> + VIR_FORCE_CLOSE(unix_fds[1]);
This doesn't look right. Even in case of failure virCommandRun* should
have closed all CLOSE_PARENT FDs. So this is effectively a double close.
> + ret = -1;
> + goto cleanup;
> + }
> +
> + memset(fds, 0, sizeof(*fds) * nfds);
> +
> + ret = virSocketRecvMultipleFDs(unix_fds[0], fds, nfds, 0);
> +
> + if (virCommandWait(cmd, &err) < 0) {
> + int i = 0;
> + for (; i < ret; ++i) {
> + if (fds[i]) {
This check seems needless. After successful return from
virSocketRecvMultipleFDs() the @fds array must be filled with only valid
FDs.
> + VIR_FORCE_CLOSE(fds[i]);
> + }
> + }
> + ret = -1;
> + }
> +
> +cleanup:
> + VIR_FORCE_CLOSE(unix_fds[0]);
> + virCommandFree(cmd);
> + return ret;
> +}
> diff --git a/src/qemu/qemu_interface.h b/src/qemu/qemu_interface.h
> index 438d548065..63d7590035 100644
> --- a/src/qemu/qemu_interface.h
> +++ b/src/qemu/qemu_interface.h
> @@ -61,3 +61,5 @@ int qemuInterfacePrepareSlirp(virQEMUDriver *driver,
> qemuSlirp **slirp);
>
> int qemuInterfaceVDPAConnect(virDomainNetDef *net) G_GNUC_NO_INLINE;
> +
> +int qemuEbpfRssHelper(const char *helper, int *fds, int nfds);
>
Michal
