Re: [PATCH 09/10] tools/xenstored: Dump delayed requests

[Julien Grall <julien@xxxxxxx>]

Hi Juergen,

On 24/06/2021 10:41, Juergen Gross wrote:
> On 16.06.21 16:43, Julien Grall wrote:
> > From: Julien Grall <jgrall@xxxxxxxxxx>
> >
> > Currently, only Live-Update request can be delayed. In a follow-up,
> > we will want to delay more requests (e.g. transaction start).
> > Therefore we want to preserve delayed requests across Live-Update.
> >
> > Delayed requests are just complete "in" buffer. So the code is
> > refactored to allow sharing the code to dump "in" buffer.
> >
> > Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
> > ---
> >   tools/xenstore/xenstored_core.c | 42 +++++++++++++++++++++++++--------
> >   1 file changed, 32 insertions(+), 10 deletions(-)
> >
> > diff --git a/tools/xenstore/xenstored_core.c 
> > b/tools/xenstore/xenstored_core.c
> > index 5b7ab7f74013..9eca58682b51 100644
> > --- a/tools/xenstore/xenstored_core.c
> > +++ b/tools/xenstore/xenstored_core.c
> > @@ -2403,25 +2403,47 @@ const char *dump_state_global(FILE *fp)
> >       return NULL;
> >   }
> > +static const char *dump_input_buffered_data(FILE *fp,
> > +                        const struct buffered_data *in,
> > +                        unsigned int *total_len)
> > +{
> > +    unsigned int hlen = in->inhdr ? in->used : sizeof(in->hdr);
> > +
> > +    *total_len += hlen;
> > +    if (fp && fwrite(&in->hdr, hlen, 1, fp) != 1)
> > +        return "Dump read data error";
> > +    if (!in->inhdr && in->used) {
> > +        *total_len += in->used;
> > +        if (fp && fwrite(in->buffer, in->used, 1, fp) != 1)
> > +            return "Dump read data error";
> > +    }
> > +
> > +    return NULL;
> > +}
> > +
> >   /* Called twice: first with fp == NULL to get length, then for 
> > writing data. */
> >   const char *dump_state_buffered_data(FILE *fp, const struct 
> > connection *c,
> >                        struct xs_state_connection *sc)
> >   {
> >       unsigned int len = 0, used;
> > -    struct buffered_data *out, *in = c->in;
> > +    struct buffered_data *out;
> >       bool partial = true;
> > +    struct delayed_request *req;
> > +    const char *ret;
> > -    if (in) {
> > -        len = in->inhdr ? in->used : sizeof(in->hdr);
> > -        if (fp && fwrite(&in->hdr, len, 1, fp) != 1)
> > -            return "Dump read data error";
> > -        if (!in->inhdr && in->used) {
> > -            len += in->used;
> > -            if (fp && fwrite(in->buffer, in->used, 1, fp) != 1)
> > -                return "Dump read data error";
> > -        }
> > +    /* Dump any command that was delayed */
> > +    list_for_each_entry(req, &c->delayed, list) {
> Please add a comment here that the following if() serves especially to
> avoid dumping the data for do_lu_start().
Would you be happy to give your acked-by/reviewed-by if I add the 
following on commit?
"
We only want to preserve commands that wasn't processed at all. All the 
other delayed requests (such as do_lu_start()) must be processed before 
Live-Update.
"

> > +        if (req->func != process_delayed_message)
> > +            continue;
> > +
> > +        assert(!req->in->inhdr);
> > +        if ((ret = dump_input_buffered_data(fp, req->in, &len)))
> > +            return ret;
> >       }
> > +    if (c->in && (ret = dump_input_buffered_data(fp, c->in, &len)))
> > +        return ret;
> > +
> >       if (sc) {
> >           sc->data_in_len = len;
> >           sc->data_resp_len = 0;
> Juergen
Cheers,

--
Julien Grall