| Message ID | 1456109555-28299-11-git-send-email-wency@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Feb 22, 2016 at 10:52:14AM +0800, Wen Congyang wrote: > Add back channel support to write stream. If the write stream is > a back channel stream, this means the write stream is used by > Secondary to send some records back. > > Signed-off-by: Yang Hongyang <hongyang.yang@easystack.cn> > Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> > --- > tools/libxl/libxl_dom_save.c | 1 + > tools/libxl/libxl_internal.h | 1 + > tools/libxl/libxl_stream_write.c | 26 ++++++++++++++++++++------ > 3 files changed, 22 insertions(+), 6 deletions(-) > > diff --git a/tools/libxl/libxl_dom_save.c b/tools/libxl/libxl_dom_save.c > index 72b61c7..18946c5 100644 > --- a/tools/libxl/libxl_dom_save.c > +++ b/tools/libxl/libxl_dom_save.c > @@ -404,6 +404,7 @@ void libxl__domain_save(libxl__egc *egc, libxl__domain_save_state *dss) > dss->sws.ao = dss->ao; > dss->sws.dss = dss; > dss->sws.fd = dss->fd; > + dss->sws.back_channel = false; > dss->sws.completion_callback = stream_done; > > libxl__stream_write_start(egc, &dss->sws); > diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h > index 3d3e8e8..e02e554 100644 > --- a/tools/libxl/libxl_internal.h > +++ b/tools/libxl/libxl_internal.h > @@ -3044,6 +3044,7 @@ struct libxl__stream_write_state { > libxl__ao *ao; > libxl__domain_save_state *dss; > int fd; > + bool back_channel; > void (*completion_callback)(libxl__egc *egc, > libxl__stream_write_state *sws, > int rc); > diff --git a/tools/libxl/libxl_stream_write.c b/tools/libxl/libxl_stream_write.c > index f6ea55d..5379126 100644 > --- a/tools/libxl/libxl_stream_write.c > +++ b/tools/libxl/libxl_stream_write.c > @@ -49,6 +49,13 @@ > * - if (hvm) > * - Emulator context record > * - Checkpoint end record > + * > + * For back channel stream: > + * - libxl__stream_write_start() > + * - Set up the stream to running state > + * > + * - Add a new API to write the record. When the record is written > + * out, call stream->checkpoint_callback() to return. What does this mean? Which new API? > */ > > /* Success/error/cleanup handling. */ > @@ -225,6 +232,15 @@ void libxl__stream_write_start(libxl__egc *egc, > > stream->running = true; > > + dc->ao = ao; > + dc->readfd = -1; > + dc->copywhat = "save v2 stream"; > + dc->writefd = stream->fd; > + dc->maxsz = -1; > + > + if (stream->back_channel) > + return; > + There seems to be very subtle change of behaviour. Before this patch, the dc->* are not set until the emulator check is done. With this path, it is possible in the normal case some of the fields are initialised in the error path. I think this is OK given the callbacks in the upper layer and in the writer don't rely on those fields to clean up. Just one thing to note. That said, I suggest you move all initialisation of dc->* in one place. > if (dss->type == LIBXL_DOMAIN_TYPE_HVM) { > stream->device_model_version = > libxl__device_model_version_running(gc, dss->domid); > @@ -249,12 +265,7 @@ void libxl__stream_write_start(libxl__egc *egc, > stream->emu_sub_hdr.index = 0; > } > > - dc->ao = ao; > - dc->readfd = -1; > dc->writewhat = "stream header"; > - dc->copywhat = "save v2 stream"; > - dc->writefd = stream->fd; > - dc->maxsz = -1; > dc->callback = stream_header_done; > > rc = libxl__datacopier_start(dc); > @@ -279,6 +290,7 @@ void libxl__stream_write_start_checkpoint(libxl__egc *egc, > { > assert(stream->running); > assert(!stream->in_checkpoint); > + assert(!stream->back_channel); > stream->in_checkpoint = true; > > write_emulator_xenstore_record(egc, stream); > @@ -590,7 +602,9 @@ static void stream_done(libxl__egc *egc, > libxl__carefd_close(stream->emu_carefd); > free(stream->emu_body); > > - check_all_finished(egc, stream, rc); > + if (!stream->back_channel) > + /* back channel stream doesn't have save helper */ > + check_all_finished(egc, stream, rc); Though it doesn't have helper, do you not need to check if the back channel stream itself is OK? The comment itself doesn't seem to justify this change. Wei. > } > > static void checkpoint_done(libxl__egc *egc, > -- > 2.5.0 > > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel
On 02/25/2016 11:54 PM, Wei Liu wrote: > On Mon, Feb 22, 2016 at 10:52:14AM +0800, Wen Congyang wrote: >> Add back channel support to write stream. If the write stream is >> a back channel stream, this means the write stream is used by >> Secondary to send some records back. >> >> Signed-off-by: Yang Hongyang <hongyang.yang@easystack.cn> >> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> >> --- >> tools/libxl/libxl_dom_save.c | 1 + >> tools/libxl/libxl_internal.h | 1 + >> tools/libxl/libxl_stream_write.c | 26 ++++++++++++++++++++------ >> 3 files changed, 22 insertions(+), 6 deletions(-) >> >> diff --git a/tools/libxl/libxl_dom_save.c b/tools/libxl/libxl_dom_save.c >> index 72b61c7..18946c5 100644 >> --- a/tools/libxl/libxl_dom_save.c >> +++ b/tools/libxl/libxl_dom_save.c >> @@ -404,6 +404,7 @@ void libxl__domain_save(libxl__egc *egc, libxl__domain_save_state *dss) >> dss->sws.ao = dss->ao; >> dss->sws.dss = dss; >> dss->sws.fd = dss->fd; >> + dss->sws.back_channel = false; >> dss->sws.completion_callback = stream_done; >> >> libxl__stream_write_start(egc, &dss->sws); >> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h >> index 3d3e8e8..e02e554 100644 >> --- a/tools/libxl/libxl_internal.h >> +++ b/tools/libxl/libxl_internal.h >> @@ -3044,6 +3044,7 @@ struct libxl__stream_write_state { >> libxl__ao *ao; >> libxl__domain_save_state *dss; >> int fd; >> + bool back_channel; >> void (*completion_callback)(libxl__egc *egc, >> libxl__stream_write_state *sws, >> int rc); >> diff --git a/tools/libxl/libxl_stream_write.c b/tools/libxl/libxl_stream_write.c >> index f6ea55d..5379126 100644 >> --- a/tools/libxl/libxl_stream_write.c >> +++ b/tools/libxl/libxl_stream_write.c >> @@ -49,6 +49,13 @@ >> * - if (hvm) >> * - Emulator context record >> * - Checkpoint end record >> + * >> + * For back channel stream: >> + * - libxl__stream_write_start() >> + * - Set up the stream to running state >> + * >> + * - Add a new API to write the record. When the record is written >> + * out, call stream->checkpoint_callback() to return. > > What does this mean? Which new API? The next patch introduces this API. The commits is very old. I think I can merge these two patches into one patch. > >> */ >> >> /* Success/error/cleanup handling. */ >> @@ -225,6 +232,15 @@ void libxl__stream_write_start(libxl__egc *egc, >> >> stream->running = true; >> >> + dc->ao = ao; >> + dc->readfd = -1; >> + dc->copywhat = "save v2 stream"; >> + dc->writefd = stream->fd; >> + dc->maxsz = -1; >> + >> + if (stream->back_channel) >> + return; >> + > > There seems to be very subtle change of behaviour. > > Before this patch, the dc->* are not set until the emulator check is > done. With this path, it is possible in the normal case some of the > fields are initialised in the error path. > > I think this is OK given the callbacks in the upper layer and in > the writer don't rely on those fields to clean up. Just one thing to > note. > > That said, I suggest you move all initialisation of dc->* in one place. OK, I will do it. > >> if (dss->type == LIBXL_DOMAIN_TYPE_HVM) { >> stream->device_model_version = >> libxl__device_model_version_running(gc, dss->domid); >> @@ -249,12 +265,7 @@ void libxl__stream_write_start(libxl__egc *egc, >> stream->emu_sub_hdr.index = 0; >> } >> >> - dc->ao = ao; >> - dc->readfd = -1; >> dc->writewhat = "stream header"; >> - dc->copywhat = "save v2 stream"; >> - dc->writefd = stream->fd; >> - dc->maxsz = -1; >> dc->callback = stream_header_done; >> >> rc = libxl__datacopier_start(dc); >> @@ -279,6 +290,7 @@ void libxl__stream_write_start_checkpoint(libxl__egc *egc, >> { >> assert(stream->running); >> assert(!stream->in_checkpoint); >> + assert(!stream->back_channel); >> stream->in_checkpoint = true; >> >> write_emulator_xenstore_record(egc, stream); >> @@ -590,7 +602,9 @@ static void stream_done(libxl__egc *egc, >> libxl__carefd_close(stream->emu_carefd); >> free(stream->emu_body); >> >> - check_all_finished(egc, stream, rc); >> + if (!stream->back_channel) >> + /* back channel stream doesn't have save helper */ >> + check_all_finished(egc, stream, rc); > > Though it doesn't have helper, do you not need to check if the back > channel stream itself is OK? The comment itself doesn't seem to justify > this change. What do you want to check? assert(!stream->shs) or assert(!libxl__stream_write_inuse(stream))? Thanks Wen Congyang > > Wei. > >> } >> >> static void checkpoint_done(libxl__egc *egc, >> -- >> 2.5.0 >> >> >> >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@lists.xen.org >> http://lists.xen.org/xen-devel > > > . >
On Fri, Feb 26, 2016 at 10:11:27AM +0800, Wen Congyang wrote: > On 02/25/2016 11:54 PM, Wei Liu wrote: > > On Mon, Feb 22, 2016 at 10:52:14AM +0800, Wen Congyang wrote: > >> Add back channel support to write stream. If the write stream is > >> a back channel stream, this means the write stream is used by > >> Secondary to send some records back. > >> > >> Signed-off-by: Yang Hongyang <hongyang.yang@easystack.cn> > >> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> > >> --- > >> tools/libxl/libxl_dom_save.c | 1 + > >> tools/libxl/libxl_internal.h | 1 + > >> tools/libxl/libxl_stream_write.c | 26 ++++++++++++++++++++------ > >> 3 files changed, 22 insertions(+), 6 deletions(-) > >> > >> diff --git a/tools/libxl/libxl_dom_save.c b/tools/libxl/libxl_dom_save.c > >> index 72b61c7..18946c5 100644 > >> --- a/tools/libxl/libxl_dom_save.c > >> +++ b/tools/libxl/libxl_dom_save.c > >> @@ -404,6 +404,7 @@ void libxl__domain_save(libxl__egc *egc, libxl__domain_save_state *dss) > >> dss->sws.ao = dss->ao; > >> dss->sws.dss = dss; > >> dss->sws.fd = dss->fd; > >> + dss->sws.back_channel = false; > >> dss->sws.completion_callback = stream_done; > >> > >> libxl__stream_write_start(egc, &dss->sws); > >> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h > >> index 3d3e8e8..e02e554 100644 > >> --- a/tools/libxl/libxl_internal.h > >> +++ b/tools/libxl/libxl_internal.h > >> @@ -3044,6 +3044,7 @@ struct libxl__stream_write_state { > >> libxl__ao *ao; > >> libxl__domain_save_state *dss; > >> int fd; > >> + bool back_channel; > >> void (*completion_callback)(libxl__egc *egc, > >> libxl__stream_write_state *sws, > >> int rc); > >> diff --git a/tools/libxl/libxl_stream_write.c b/tools/libxl/libxl_stream_write.c > >> index f6ea55d..5379126 100644 > >> --- a/tools/libxl/libxl_stream_write.c > >> +++ b/tools/libxl/libxl_stream_write.c > >> @@ -49,6 +49,13 @@ > >> * - if (hvm) > >> * - Emulator context record > >> * - Checkpoint end record > >> + * > >> + * For back channel stream: > >> + * - libxl__stream_write_start() > >> + * - Set up the stream to running state > >> + * > >> + * - Add a new API to write the record. When the record is written > >> + * out, call stream->checkpoint_callback() to return. > > > > What does this mean? Which new API? > > The next patch introduces this API. The commits is very old. > > I think I can merge these two patches into one patch. > Please reference the actual function / API. > > > >> */ > >> > >> /* Success/error/cleanup handling. */ > >> @@ -225,6 +232,15 @@ void libxl__stream_write_start(libxl__egc *egc, > >> > >> stream->running = true; > >> > >> + dc->ao = ao; > >> + dc->readfd = -1; > >> + dc->copywhat = "save v2 stream"; > >> + dc->writefd = stream->fd; > >> + dc->maxsz = -1; > >> + > >> + if (stream->back_channel) > >> + return; > >> + > > > > There seems to be very subtle change of behaviour. > > > > Before this patch, the dc->* are not set until the emulator check is > > done. With this path, it is possible in the normal case some of the > > fields are initialised in the error path. > > > > I think this is OK given the callbacks in the upper layer and in > > the writer don't rely on those fields to clean up. Just one thing to > > note. > > > > That said, I suggest you move all initialisation of dc->* in one place. > > OK, I will do it. > > > > >> if (dss->type == LIBXL_DOMAIN_TYPE_HVM) { > >> stream->device_model_version = > >> libxl__device_model_version_running(gc, dss->domid); > >> @@ -249,12 +265,7 @@ void libxl__stream_write_start(libxl__egc *egc, > >> stream->emu_sub_hdr.index = 0; > >> } > >> > >> - dc->ao = ao; > >> - dc->readfd = -1; > >> dc->writewhat = "stream header"; > >> - dc->copywhat = "save v2 stream"; > >> - dc->writefd = stream->fd; > >> - dc->maxsz = -1; > >> dc->callback = stream_header_done; > >> > >> rc = libxl__datacopier_start(dc); > >> @@ -279,6 +290,7 @@ void libxl__stream_write_start_checkpoint(libxl__egc *egc, > >> { > >> assert(stream->running); > >> assert(!stream->in_checkpoint); > >> + assert(!stream->back_channel); > >> stream->in_checkpoint = true; > >> > >> write_emulator_xenstore_record(egc, stream); > >> @@ -590,7 +602,9 @@ static void stream_done(libxl__egc *egc, > >> libxl__carefd_close(stream->emu_carefd); > >> free(stream->emu_body); > >> > >> - check_all_finished(egc, stream, rc); > >> + if (!stream->back_channel) > >> + /* back channel stream doesn't have save helper */ > >> + check_all_finished(egc, stream, rc); > > > > Though it doesn't have helper, do you not need to check if the back > > channel stream itself is OK? The comment itself doesn't seem to justify > > this change. > > What do you want to check? assert(!stream->shs) or > assert(!libxl__stream_write_inuse(stream))? The stream itself is not in use. Also check_all_finished calls completion_callback. Don't you need that, too? Wei. > > Thanks > Wen Congyang > > > > > Wei. > > > >> } > >> > >> static void checkpoint_done(libxl__egc *egc, > >> -- > >> 2.5.0 > >> > >> > >> > >> > >> _______________________________________________ > >> Xen-devel mailing list > >> Xen-devel@lists.xen.org > >> http://lists.xen.org/xen-devel > > > > > > . > > > > >
On 03/02/2016 11:02 PM, Wei Liu wrote: > On Fri, Feb 26, 2016 at 10:11:27AM +0800, Wen Congyang wrote: >> On 02/25/2016 11:54 PM, Wei Liu wrote: >>> On Mon, Feb 22, 2016 at 10:52:14AM +0800, Wen Congyang wrote: >>>> Add back channel support to write stream. If the write stream is >>>> a back channel stream, this means the write stream is used by >>>> Secondary to send some records back. >>>> >>>> Signed-off-by: Yang Hongyang <hongyang.yang@easystack.cn> >>>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> >>>> --- >>>> tools/libxl/libxl_dom_save.c | 1 + >>>> tools/libxl/libxl_internal.h | 1 + >>>> tools/libxl/libxl_stream_write.c | 26 ++++++++++++++++++++------ >>>> 3 files changed, 22 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/tools/libxl/libxl_dom_save.c b/tools/libxl/libxl_dom_save.c >>>> index 72b61c7..18946c5 100644 >>>> --- a/tools/libxl/libxl_dom_save.c >>>> +++ b/tools/libxl/libxl_dom_save.c >>>> @@ -404,6 +404,7 @@ void libxl__domain_save(libxl__egc *egc, libxl__domain_save_state *dss) >>>> dss->sws.ao = dss->ao; >>>> dss->sws.dss = dss; >>>> dss->sws.fd = dss->fd; >>>> + dss->sws.back_channel = false; >>>> dss->sws.completion_callback = stream_done; >>>> >>>> libxl__stream_write_start(egc, &dss->sws); >>>> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h >>>> index 3d3e8e8..e02e554 100644 >>>> --- a/tools/libxl/libxl_internal.h >>>> +++ b/tools/libxl/libxl_internal.h >>>> @@ -3044,6 +3044,7 @@ struct libxl__stream_write_state { >>>> libxl__ao *ao; >>>> libxl__domain_save_state *dss; >>>> int fd; >>>> + bool back_channel; >>>> void (*completion_callback)(libxl__egc *egc, >>>> libxl__stream_write_state *sws, >>>> int rc); >>>> diff --git a/tools/libxl/libxl_stream_write.c b/tools/libxl/libxl_stream_write.c >>>> index f6ea55d..5379126 100644 >>>> --- a/tools/libxl/libxl_stream_write.c >>>> +++ b/tools/libxl/libxl_stream_write.c >>>> @@ -49,6 +49,13 @@ >>>> * - if (hvm) >>>> * - Emulator context record >>>> * - Checkpoint end record >>>> + * >>>> + * For back channel stream: >>>> + * - libxl__stream_write_start() >>>> + * - Set up the stream to running state >>>> + * >>>> + * - Add a new API to write the record. When the record is written >>>> + * out, call stream->checkpoint_callback() to return. >>> >>> What does this mean? Which new API? >> >> The next patch introduces this API. The commits is very old. >> >> I think I can merge these two patches into one patch. >> > > Please reference the actual function / API. > >>> >>>> */ >>>> >>>> /* Success/error/cleanup handling. */ >>>> @@ -225,6 +232,15 @@ void libxl__stream_write_start(libxl__egc *egc, >>>> >>>> stream->running = true; >>>> >>>> + dc->ao = ao; >>>> + dc->readfd = -1; >>>> + dc->copywhat = "save v2 stream"; >>>> + dc->writefd = stream->fd; >>>> + dc->maxsz = -1; >>>> + >>>> + if (stream->back_channel) >>>> + return; >>>> + >>> >>> There seems to be very subtle change of behaviour. >>> >>> Before this patch, the dc->* are not set until the emulator check is >>> done. With this path, it is possible in the normal case some of the >>> fields are initialised in the error path. >>> >>> I think this is OK given the callbacks in the upper layer and in >>> the writer don't rely on those fields to clean up. Just one thing to >>> note. >>> >>> That said, I suggest you move all initialisation of dc->* in one place. >> >> OK, I will do it. >> >>> >>>> if (dss->type == LIBXL_DOMAIN_TYPE_HVM) { >>>> stream->device_model_version = >>>> libxl__device_model_version_running(gc, dss->domid); >>>> @@ -249,12 +265,7 @@ void libxl__stream_write_start(libxl__egc *egc, >>>> stream->emu_sub_hdr.index = 0; >>>> } >>>> >>>> - dc->ao = ao; >>>> - dc->readfd = -1; >>>> dc->writewhat = "stream header"; >>>> - dc->copywhat = "save v2 stream"; >>>> - dc->writefd = stream->fd; >>>> - dc->maxsz = -1; >>>> dc->callback = stream_header_done; >>>> >>>> rc = libxl__datacopier_start(dc); >>>> @@ -279,6 +290,7 @@ void libxl__stream_write_start_checkpoint(libxl__egc *egc, >>>> { >>>> assert(stream->running); >>>> assert(!stream->in_checkpoint); >>>> + assert(!stream->back_channel); >>>> stream->in_checkpoint = true; >>>> >>>> write_emulator_xenstore_record(egc, stream); >>>> @@ -590,7 +602,9 @@ static void stream_done(libxl__egc *egc, >>>> libxl__carefd_close(stream->emu_carefd); >>>> free(stream->emu_body); >>>> >>>> - check_all_finished(egc, stream, rc); >>>> + if (!stream->back_channel) >>>> + /* back channel stream doesn't have save helper */ >>>> + check_all_finished(egc, stream, rc); >>> >>> Though it doesn't have helper, do you not need to check if the back >>> channel stream itself is OK? The comment itself doesn't seem to justify >>> this change. >> >> What do you want to check? assert(!stream->shs) or >> assert(!libxl__stream_write_inuse(stream))? > > > The stream itself is not in use. We set stream->running to false in stream_done, so libxl__stream_write_inuse() will return false. So I think there is no need to check it. I will update the comments to document it. > > Also check_all_finished calls completion_callback. Don't you need that, > too? back channel stream doesn't have completion_callback. See the comments in check_all_finished(). Thanks Wen Congyang > > Wei. > >> >> Thanks >> Wen Congyang >> >>> >>> Wei. >>> >>>> } >>>> >>>> static void checkpoint_done(libxl__egc *egc, >>>> -- >>>> 2.5.0 >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> Xen-devel mailing list >>>> Xen-devel@lists.xen.org >>>> http://lists.xen.org/xen-devel >>> >>> >>> . >>> >> >> >> > > > . >
diff --git a/tools/libxl/libxl_dom_save.c b/tools/libxl/libxl_dom_save.c index 72b61c7..18946c5 100644 --- a/tools/libxl/libxl_dom_save.c +++ b/tools/libxl/libxl_dom_save.c @@ -404,6 +404,7 @@ void libxl__domain_save(libxl__egc *egc, libxl__domain_save_state *dss) dss->sws.ao = dss->ao; dss->sws.dss = dss; dss->sws.fd = dss->fd; + dss->sws.back_channel = false; dss->sws.completion_callback = stream_done; libxl__stream_write_start(egc, &dss->sws); diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h index 3d3e8e8..e02e554 100644 --- a/tools/libxl/libxl_internal.h +++ b/tools/libxl/libxl_internal.h @@ -3044,6 +3044,7 @@ struct libxl__stream_write_state { libxl__ao *ao; libxl__domain_save_state *dss; int fd; + bool back_channel; void (*completion_callback)(libxl__egc *egc, libxl__stream_write_state *sws, int rc); diff --git a/tools/libxl/libxl_stream_write.c b/tools/libxl/libxl_stream_write.c index f6ea55d..5379126 100644 --- a/tools/libxl/libxl_stream_write.c +++ b/tools/libxl/libxl_stream_write.c @@ -49,6 +49,13 @@ * - if (hvm) * - Emulator context record * - Checkpoint end record + * + * For back channel stream: + * - libxl__stream_write_start() + * - Set up the stream to running state + * + * - Add a new API to write the record. When the record is written + * out, call stream->checkpoint_callback() to return. */ /* Success/error/cleanup handling. */ @@ -225,6 +232,15 @@ void libxl__stream_write_start(libxl__egc *egc, stream->running = true; + dc->ao = ao; + dc->readfd = -1; + dc->copywhat = "save v2 stream"; + dc->writefd = stream->fd; + dc->maxsz = -1; + + if (stream->back_channel) + return; + if (dss->type == LIBXL_DOMAIN_TYPE_HVM) { stream->device_model_version = libxl__device_model_version_running(gc, dss->domid); @@ -249,12 +265,7 @@ void libxl__stream_write_start(libxl__egc *egc, stream->emu_sub_hdr.index = 0; } - dc->ao = ao; - dc->readfd = -1; dc->writewhat = "stream header"; - dc->copywhat = "save v2 stream"; - dc->writefd = stream->fd; - dc->maxsz = -1; dc->callback = stream_header_done; rc = libxl__datacopier_start(dc); @@ -279,6 +290,7 @@ void libxl__stream_write_start_checkpoint(libxl__egc *egc, { assert(stream->running); assert(!stream->in_checkpoint); + assert(!stream->back_channel); stream->in_checkpoint = true; write_emulator_xenstore_record(egc, stream); @@ -590,7 +602,9 @@ static void stream_done(libxl__egc *egc, libxl__carefd_close(stream->emu_carefd); free(stream->emu_body); - check_all_finished(egc, stream, rc); + if (!stream->back_channel) + /* back channel stream doesn't have save helper */ + check_all_finished(egc, stream, rc); } static void checkpoint_done(libxl__egc *egc,