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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2/5] libxl: call hotplug scripts from libxl for vbd
On Mon, 2012-04-16 at 16:06 +0100, Roger Pau Monne wrote:
> This is a rather big change, that adds the necessary machinery to perform
> hotplug script calling from libxl for Linux. This patch launches the necessary
> scripts to attach and detach PHY and TAP backend types (Qemu doesn't use
> hotplug
> scripts).
>
> Here's a list of the major changes introduced:
>
> * libxl_device_disk_add makes use of the new event library and takes the
> optional parameter libxl_asyncop_how, to choose how the operation has to be
> issued (sync or async).
>
> * libxl_device_disk_add waits for backend to switch to state 2
> (XenbusInitWait)
> and then launches the hotplug script.
>
> * libxl__devices_destroy no longer calls libxl__device_destroy, and instead
> calls libxl__initiate_device_remove, so we can disconnect the device and
> execute the necessary hotplug scripts instead of just deleting the backend
> entries. So libxl__devices_destroy now uses the event library, and so does
> libxl_domain_destroy.
>
> * Since libxl__devices_destroy calls multiple times
> libxl__initiate_device_remove, this function now returns a different value
> regarding the actions taken (if an event was added or not). The user has to
> call libxl__ao_complete after using this function if necessary.
>
> * The internal API for hotplug scripts has been added, which consists of one
> function; libxl__device_hotplug that takes the device and the action to
> execute.
>
> * Linux hotplug scripts are called by setting the necessary env variables to
> emulate udev rules, so there's no need to change them (although a rework to
> pass this as parameters insted of env variables would be suitable, so both
> NetBSD and Linux hotplug scripts take the same parameters).
>
> * Added a check in xen-hotplug-common.sh, so scripts are only executed from
> udev when using xend. xl adds an execute_udev=n to xenstore device backend
> and passes XL_CALL=y to the env of the script call, and udev calls check
> that
> execute_udev is not set and XL_CALL is empty also.
>
> I've also modified the python binding for pyxl_domain_destroy, that now take
> the
> ao_how parameter, but I'm not really sure if it's done correctly, let's just
> say
> that it compiles.
>
> Signed-off-by: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> ---
> tools/hotplug/Linux/xen-hotplug-common.sh | 6 ++
> tools/libxl/Makefile | 3 +-
> tools/libxl/libxl.c | 104 ++++++++++++++++++----
> tools/libxl/libxl.h | 7 +-
> tools/libxl/libxl_create.c | 4 +-
> tools/libxl/libxl_device.c | 140
> +++++++++++++++++++++++++++--
> tools/libxl/libxl_dm.c | 4 +-
> tools/libxl/libxl_hotplug.c | 67 ++++++++++++++
> tools/libxl/libxl_internal.h | 43 +++++++++-
> tools/libxl/libxl_linux.c | 117 ++++++++++++++++++++++++
> tools/libxl/xl_cmdimpl.c | 14 ++--
> tools/python/xen/lowlevel/xl/xl.c | 5 +-
> 12 files changed, 474 insertions(+), 40 deletions(-)
> create mode 100644 tools/libxl/libxl_hotplug.c
>
> diff --git a/tools/hotplug/Linux/xen-hotplug-common.sh
> b/tools/hotplug/Linux/xen-hotplug-common.sh
> index 8f6557d..dc3e867 100644
> --- a/tools/hotplug/Linux/xen-hotplug-common.sh
> +++ b/tools/hotplug/Linux/xen-hotplug-common.sh
> @@ -15,6 +15,12 @@
> # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> #
>
> +# Hack to prevent the execution of hotplug scripts form udev if the domain
from
> +# has ben launched from libxl
been
> +execute_udev=`xenstore-read $XENBUS_PATH/execute_udev 2>/dev/null`
> +if [ -n "$execute_udev" ] && [ -z "$XL_CALL" ]; then
> + exit 0
> +fi
So, am I right that in some future world where we have got rid of xend
and made this stuff work without udev everywhere (e.g. including driver
domains) there is a path to deprecating this snippet without requiring
everyone to go through some sort of transition?
Or are we stuck with this envvar forever? It's not a big deal but if we
can invert it (e.g. by setting ENV{HOTPLUG_GATE}=${XENBUS}/evecute_udev
in xen-backend.rules and ...if -n "${HOTPLUG_GATE}" && xenstore-read
${HOTPLUG_GATE}... etc) then that would be nicer?
> dir=$(dirname "$0")
> . "$dir/hotplugpath.sh"
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index 16ebef3..fb4fbf2 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -1062,13 +1062,15 @@ void libxl_evdisable_disk_eject(libxl_ctx *ctx,
> libxl_evgen_disk_eject *evg) {
> GC_FREE;
> }
>
> -int libxl_domain_destroy(libxl_ctx *ctx, uint32_t domid)
> +int libxl_domain_destroy(libxl_ctx *ctx, uint32_t domid,
> + const libxl_asyncop_how *ao_how)
> {
> - GC_INIT(ctx);
> + AO_CREATE(ctx, domid, ao_how);
> char *dom_path;
> char *vm_path;
> char *pid;
> int rc, dm_present;
> + int rc_ao = 0;
>
> rc = libxl_domain_info(ctx, NULL, domid);
> switch(rc) {
> @@ -1110,7 +1112,8 @@ int libxl_domain_destroy(libxl_ctx *ctx, uint32_t domid)
>
> libxl__qmp_cleanup(gc, domid);
> }
> - if (libxl__devices_destroy(gc, domid) < 0)
> + rc_ao = libxl__devices_destroy(egc, ao, domid);
> + if (rc_ao < 0)
> LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
> "libxl__devices_destroy failed for %d", domid);
>
> @@ -1133,9 +1136,10 @@ int libxl_domain_destroy(libxl_ctx *ctx, uint32_t
> domid)
> goto out;
> }
> rc = 0;
> +
> out:
> - GC_FREE;
> - return rc;
> + if (rc_ao) return AO_ABORT(rc_ao);
> + return AO_INPROGRESS;
> }
>
> int libxl_console_exec(libxl_ctx *ctx, uint32_t domid, int cons_num,
> libxl_console_type type)
> @@ -1313,9 +1317,11 @@ static int libxl__device_from_disk(libxl__gc *gc,
> uint32_t domid,
> return 0;
> }
>
> -int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid, libxl_device_disk
> *disk)
> +int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid,
> + libxl_device_disk *disk,
> + const libxl_asyncop_how *ao_how)
> {
> - GC_INIT(ctx);
> + AO_CREATE(ctx, domid, ao_how);
> flexarray_t *front;
> flexarray_t *back;
> char *dev;
> @@ -1330,7 +1336,7 @@ int libxl_device_disk_add(libxl_ctx *ctx, uint32_t
> domid, libxl_device_disk *dis
> rc = ERROR_NOMEM;
> goto out;
> }
> - back = flexarray_make(16, 1);
> + back = flexarray_make(20, 1);
> if (!back) {
> rc = ERROR_NOMEM;
> goto out_free;
> @@ -1361,6 +1367,11 @@ int libxl_device_disk_add(libxl_ctx *ctx, uint32_t
> domid, libxl_device_disk *dis
> flexarray_append(back, "params");
> flexarray_append(back, dev);
>
> + flexarray_append(back, "script");
> + flexarray_append(back, libxl__sprintf(gc, "%s/%s",
> +
> libxl_xen_script_dir_path(),
> + "block"));
> +
> assert(device.backend_kind == LIBXL__DEVICE_KIND_VBD);
> break;
> case LIBXL_DISK_BACKEND_TAP:
> @@ -1374,6 +1385,11 @@ int libxl_device_disk_add(libxl_ctx *ctx, uint32_t
> domid, libxl_device_disk *dis
> libxl__device_disk_string_of_format(disk->format),
> disk->pdev_path));
>
> + flexarray_append(back, "script");
> + flexarray_append(back, libxl__sprintf(gc, "%s/%s",
> + libxl_xen_script_dir_path(),
> + "blktap"));
> +
> /* now create a phy device to export the device to the guest */
> goto do_backend_phy;
> case LIBXL_DISK_BACKEND_QDISK:
> @@ -1406,6 +1422,9 @@ int libxl_device_disk_add(libxl_ctx *ctx, uint32_t
> domid, libxl_device_disk *dis
> flexarray_append(back, disk->readwrite ? "w" : "r");
> flexarray_append(back, "device-type");
> flexarray_append(back, disk->is_cdrom ? "cdrom" : "disk");
> + /* compatibility addon to keep udev rules */
> + flexarray_append(back, "execute_udev");
> + flexarray_append(back, "n");
>
> flexarray_append(front, "backend-id");
> flexarray_append(front, libxl__sprintf(gc, "%d", disk->backend_domid));
> @@ -1420,14 +1439,23 @@ int libxl_device_disk_add(libxl_ctx *ctx, uint32_t
> domid, libxl_device_disk *dis
> libxl__xs_kvs_of_flexarray(gc, back,
> back->count),
> libxl__xs_kvs_of_flexarray(gc, front,
> front->count));
>
> + if (disk->backend == LIBXL_DISK_BACKEND_PHY ||
> + disk->backend == LIBXL_DISK_BACKEND_TAP) {
> + rc = libxl__initiate_device_add(egc, ao, &device);
> + if (rc) goto out_free;
> + } else {
> + /* no need to execute hotplug scripts */
> + libxl__ao_complete(egc, ao, 0);
> + }
This would be better as a switch, since it would make it more obvious
that the "else" is actually "case LIBXL_DISK_BACKEND_QDISK" etc.
[...]
> +
> +/*
> + * Return codes:
> + * 1 Success and event(s) HAVE BEEN added
> + * 0 Success and NO events where added
were
(I saw a few of these)
> + * < 0 Error
> + *
> + * Since this function can be called several times, and several events
> + * can be added to the same context, the user has to call
> + * libxl__ao_complete when necessary (if no events are added).
> + */
> int libxl__initiate_device_remove(libxl__egc *egc, libxl__ao *ao,
> libxl__device *dev)
> {
> @@ -392,7 +461,6 @@ int libxl__initiate_device_remove(libxl__egc *egc,
> libxl__ao *ao,
[...]
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