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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 11/23] libxc: suspend: Rename, improve xc_suspend_evtchn_init
On Tue, 2013-12-17 at 18:35 +0000, Ian Jackson wrote:
> xc_suspend_evtchn_init expects to eat the first event on the xce. If
> the xce is used for any other purpose then this can break. Document
> this fact and rename the function to xc_suspend_evtchn_init_exclusive.
> (I haven't checked the call sites for improper shared use of the xce.)
>
> Provide a corresponding xc_suspend_evtchn_init_sane which doesn't try
> to eat an event, and instead leaves the caller the ability to
> demultiplex.
I'd much rather have fixed the existing one (and its callers as
necessary) but I can see why you wouldn't have the appetite for that.
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
>
> Also document that xc_await_suspend needs exclusive use of the xce.
>
> Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
> CC: Shriram Rajagopalan <rshriram@xxxxxxxxx>
> ---
> tools/libxc/xc_suspend.c | 21
> ++++++++++++++++----
> tools/libxc/xenguest.h | 13 +++++++++++-
> tools/libxl/libxl_dom.c | 2 +-
> tools/misc/xen-hptool.c | 2 +-
> .../python/xen/lowlevel/checkpoint/libcheckpoint.c | 2 +-
> tools/xcutils/xc_save.c | 2 +-
> 6 files changed, 33 insertions(+), 9 deletions(-)
>
> diff --git a/tools/libxc/xc_suspend.c b/tools/libxc/xc_suspend.c
> index 1ace411..7968a44 100644
> --- a/tools/libxc/xc_suspend.c
> +++ b/tools/libxc/xc_suspend.c
> @@ -14,6 +14,8 @@
> * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
> USA
> */
>
> +#include <assert.h>
> +
> #include "xc_private.h"
> #include "xenguest.h"
>
> @@ -102,7 +104,7 @@ int xc_suspend_evtchn_release(xc_interface *xch,
> xc_evtchn *xce, int domid, int
> return unlock_suspend_event(xch, domid);
> }
>
> -int xc_suspend_evtchn_init(xc_interface *xch, xc_evtchn *xce, int domid, int
> port)
> +int xc_suspend_evtchn_init_sane(xc_interface *xch, xc_evtchn *xce, int
> domid, int port)
> {
> int rc, suspend_evtchn = -1;
>
> @@ -121,9 +123,6 @@ int xc_suspend_evtchn_init(xc_interface *xch, xc_evtchn
> *xce, int domid, int por
> goto cleanup;
> }
>
> - /* event channel is pending immediately after binding */
> - xc_await_suspend(xch, xce, suspend_evtchn);
> -
> return suspend_evtchn;
>
> cleanup:
> @@ -132,3 +131,17 @@ cleanup:
>
> return -1;
> }
> +
> +int xc_suspend_evtchn_init_exclusive(xc_interface *xch, xc_evtchn *xce, int
> domid, int port)
> +{
> + int suspend_evtchn;
> +
> + suspend_evtchn = xc_suspend_evtchn_init_sane(xch, xce, domid, port);
> + if (suspend_evtchn < 0)
> + return suspend_evtchn;
> +
> + /* event channel is pending immediately after binding */
> + xc_await_suspend(xch, xce, suspend_evtchn);
> +
> + return suspend_evtchn;
> +}
> diff --git a/tools/libxc/xenguest.h b/tools/libxc/xenguest.h
> index a0e30e1..ce5456c 100644
> --- a/tools/libxc/xenguest.h
> +++ b/tools/libxc/xenguest.h
> @@ -256,10 +256,21 @@ int xc_hvm_build_target_mem(xc_interface *xch,
>
> int xc_suspend_evtchn_release(xc_interface *xch, xc_evtchn *xce, int domid,
> int suspend_evtchn);
>
> -int xc_suspend_evtchn_init(xc_interface *xch, xc_evtchn *xce, int domid, int
> port);
> +/**
> + * This function eats the initial notification.
> + * xce must not be used for anything else
> + */
> +int xc_suspend_evtchn_init_exclusive(xc_interface *xch, xc_evtchn *xce, int
> domid, int port);
>
> +/* xce must not be used for anything else */
> int xc_await_suspend(xc_interface *xch, xc_evtchn *xce, int suspend_evtchn);
>
> +/**
> + * The port will be signaled immediately after this call
> + * The caller should check the domain status and look for the next event
> + */
> +int xc_suspend_evtchn_init_sane(xc_interface *xch, xc_evtchn *xce, int
> domid, int port);
> +
> int xc_get_bit_size(xc_interface *xch,
> const char *image_name, const char *cmdline,
> const char *features, int *type);
> diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
> index 55f74b2..4b42856 100644
> --- a/tools/libxl/libxl_dom.c
> +++ b/tools/libxl/libxl_dom.c
> @@ -1358,7 +1358,7 @@ void libxl__domain_suspend(libxl__egc *egc,
> libxl__domain_suspend_state *dss)
>
> if (port >= 0) {
> dss->suspend_eventchn =
> - xc_suspend_evtchn_init(CTX->xch, dss->xce, dss->domid, port);
> + xc_suspend_evtchn_init_exclusive(CTX->xch, dss->xce,
> dss->domid, port);
>
> if (dss->suspend_eventchn < 0)
> LOG(WARN, "Suspend event channel initialization failed");
> diff --git a/tools/misc/xen-hptool.c b/tools/misc/xen-hptool.c
> index 24c3e95..db76f79 100644
> --- a/tools/misc/xen-hptool.c
> +++ b/tools/misc/xen-hptool.c
> @@ -112,7 +112,7 @@ static int suspend_guest(xc_interface *xch, xc_evtchn
> *xce, int domid, int *evtc
> fprintf(stderr, "DOM%d: No suspend port, try live migration\n",
> domid);
> goto failed;
> }
> - suspend_evtchn = xc_suspend_evtchn_init(xch, xce, domid, port);
> + suspend_evtchn = xc_suspend_evtchn_init_exclusive(xch, xce, domid, port);
> if (suspend_evtchn < 0)
> {
> fprintf(stderr, "Suspend evtchn initialization failed\n");
> diff --git a/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c
> b/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c
> index 01c0d47..817d272 100644
> --- a/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c
> +++ b/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c
> @@ -360,7 +360,7 @@ static int setup_suspend_evtchn(checkpoint_state* s)
> return -1;
> }
>
> - s->suspend_evtchn = xc_suspend_evtchn_init(s->xch, s->xce, s->domid, port);
> + s->suspend_evtchn = xc_suspend_evtchn_init_exclusive(s->xch, s->xce,
> s->domid, port);
> if (s->suspend_evtchn < 0) {
> s->errstr = "failed to bind suspend event channel";
> return -1;
> diff --git a/tools/xcutils/xc_save.c b/tools/xcutils/xc_save.c
> index e34bd2c..974f706 100644
> --- a/tools/xcutils/xc_save.c
> +++ b/tools/xcutils/xc_save.c
> @@ -202,7 +202,7 @@ main(int argc, char **argv)
> else
> {
> si.suspend_evtchn =
> - xc_suspend_evtchn_init(si.xch, si.xce, si.domid, port);
> + xc_suspend_evtchn_init_exclusive(si.xch, si.xce, si.domid,
> port);
>
> if (si.suspend_evtchn < 0)
> warnx("suspend event channel initialization failed, "
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