Re: [PATCH v2 09/10] libxl: Fix libxl_set_memory_target return value

From: Paulina Szubarczyk <paulinaszubarczyk@gmail.com>
To: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: "Wei Liu" <wei.liu2@citrix.com>,
	"Ian Campbell" <ian.campbell@citrix.com>,
	"Dario Faggioli" <dario.faggioli@citrix.com>,
	"Ian Jackson" <ian.jackson@eu.citrix.com>,
	xen-devel <xen-devel@lists.xenproject.org>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH v2 09/10] libxl: Fix libxl_set_memory_target return value
Date: Wed, 06 Apr 2016 15:21:21 +0200	[thread overview]
Message-ID: <1459948881.21096.9.camel@localhost> (raw)
In-Reply-To: <CAFLBxZa=D37X7AX78DrAWdH_GHZoit2B8yBwvrAUfWs4FEV2NA@mail.gmail.com>

On Wed, 2016-04-06 at 13:54 +0100, George Dunlap wrote:
> On Wed, Apr 6, 2016 at 12:46 PM, Paulina Szubarczyk
> <paulinaszubarczyk@gmail.com> wrote:
> > From: George Dunlap <George.Dunlap@eu.citrix.com>
> >
> > libxl_set_memory_target seems to have the following return values:
> >
> > * 1 on failure, if the failure happens because of a xenstore error *or*
> > * invalid target
> >
> > * -1 if the setmaxmem hypercall
> >
> > * -errno if the set_pod_target hypercall target fails
> >
> > * 0 on success
> >
> > Make it consistently return ERROR_FAIL on failure, unless the
> > parameters were invalid, in which case return ERROR_INVAL.
> >
> > In accordance with CODING_SYTLE:
> >
> > 1. Leave rc uninitialized, and set when an error is detected
> >
> > 2. Use 'r' for return values to functions whose return values are a
> > different error space (like xc_domain_setmaxmem and
> > xc_domain_set_pod_target)
> >
> > ---
> > Changed since v1:
> >
> > 3. Use 'lrc' for return values to local functions libxl__*
> > where a failure means retry, rather than fail the whole function
> > (libxl__fill_dom0_memory_info), to reduce the risk of that.
> >
> > Signed-off-by: George Dunlap <George.Dunlap@eu.citrix.com>
> > Signed-off-by: Paulina Szubarczyk <paulinaszubarczyk@gmail.com>
> 
> FYI everything after the "---" will be discarded on commit; so you
> need all the tags (signed-off-by, acked-by, &c) to be before that.
> 
>  -George
> 
I did not know that. Thank you. I was suggested by the wiki page,
where the example resend comments starts after the "---" but 
the tags you mentioned are earlier. 

But that confused me a bit, so after that "---" there should be comments
for reviewers rather then information about changes.

Should I re-send it now or may I do it with the changes after review?

Paulina
> > ---
> >  tools/libxl/libxl.c | 28 ++++++++++++++++++----------
> >  1 file changed, 18 insertions(+), 10 deletions(-)
> >
> > diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> > index 75f00be..057366e 100644
> > --- a/tools/libxl/libxl.c
> > +++ b/tools/libxl/libxl.c
> > @@ -4824,7 +4824,7 @@ int libxl_set_memory_target(libxl_ctx *ctx, uint32_t domid,
> >          int32_t target_memkb, int relative, int enforce)
> >  {
> >      GC_INIT(ctx);
> > -    int rc = 1, abort_transaction = 0;
> > +    int rc, r, lrc, abort_transaction = 0;
> >      uint64_t memorykb;
> >      uint32_t videoram = 0;
> >      uint32_t current_target_memkb = 0, new_target_memkb = 0;
> > @@ -4852,15 +4852,15 @@ retry_transaction:
> >      if (!target && !domid) {
> >          if (!xs_transaction_end(ctx->xsh, t, 1))
> >              goto out_no_transaction;
> > -        rc = libxl__fill_dom0_memory_info(gc, &current_target_memkb,
> > +        lrc = libxl__fill_dom0_memory_info(gc, &current_target_memkb,
> >                                            &current_max_memkb);
> > -        if (rc < 0)
> > -            goto out_no_transaction;
> > +        if (lrc < 0) { rc = ERROR_FAIL; goto out_no_transaction; }
> >          goto retry_transaction;
> >      } else if (!target) {
> >          LOGE(ERROR, "cannot get target memory info from %s/memory/target",
> >               dompath);
> >          abort_transaction = 1;
> > +        rc = ERROR_FAIL;
> >          goto out;
> >      } else {
> >          current_target_memkb = strtoul(target, &endptr, 10);
> > @@ -4868,6 +4868,7 @@ retry_transaction:
> >              LOGE(ERROR, "invalid memory target %s from %s/memory/target\n",
> >                   target, dompath);
> >              abort_transaction = 1;
> > +            rc = ERROR_FAIL;
> >              goto out;
> >          }
> >      }
> > @@ -4876,6 +4877,7 @@ retry_transaction:
> >          LOGE(ERROR, "cannot get memory info from %s/memory/static-max",
> >               dompath);
> >          abort_transaction = 1;
> > +        rc = ERROR_FAIL;
> >          goto out;
> >      }
> >      memorykb = strtoul(memmax, &endptr, 10);
> > @@ -4883,6 +4885,7 @@ retry_transaction:
> >          LOGE(ERROR, "invalid max memory %s from %s/memory/static-max\n",
> >               memmax, dompath);
> >          abort_transaction = 1;
> > +        rc = ERROR_FAIL;
> >          goto out;
> >      }
> >
> > @@ -4902,6 +4905,7 @@ retry_transaction:
> >              "memory_dynamic_max must be less than or equal to"
> >              " memory_static_max\n");
> >          abort_transaction = 1;
> > +        rc = ERROR_INVAL;
> >          goto out;
> >      }
> >
> > @@ -4909,33 +4913,36 @@ retry_transaction:
> >          LOG(ERROR, "new target %d for dom0 is below the minimum threshold",
> >              new_target_memkb);
> >          abort_transaction = 1;
> > +        rc = ERROR_INVAL;
> >          goto out;
> >      }
> >
> >      if (enforce) {
> >          memorykb = new_target_memkb + videoram;
> > -        rc = xc_domain_setmaxmem(ctx->xch, domid, memorykb +
> > +        r = xc_domain_setmaxmem(ctx->xch, domid, memorykb +
> >                  LIBXL_MAXMEM_CONSTANT);
> > -        if (rc != 0) {
> > +        if (r != 0) {
> >              LOGE(ERROR,
> >                   "xc_domain_setmaxmem domid=%u memkb=%"PRIu64" failed ""rc=%d\n",
> >                   domid,
> >                   memorykb + LIBXL_MAXMEM_CONSTANT,
> > -                 rc);
> > +                 r);
> >              abort_transaction = 1;
> > +            rc = ERROR_FAIL;
> >              goto out;
> >          }
> >      }
> >
> > -    rc = xc_domain_set_pod_target(ctx->xch, domid,
> > +    r = xc_domain_set_pod_target(ctx->xch, domid,
> >              (new_target_memkb + LIBXL_MAXMEM_CONSTANT) / 4, NULL, NULL, NULL);
> > -    if (rc != 0) {
> > +    if (r != 0) {
> >          LOGE(ERROR,
> >               "xc_domain_set_pod_target domid=%d, memkb=%d ""failed rc=%d\n",
> >               domid,
> >               new_target_memkb / 4,
> > -             rc);
> > +             r);
> >          abort_transaction = 1;
> > +        rc = ERROR_FAIL;
> >          goto out;
> >      }
> >
> > @@ -4949,6 +4956,7 @@ retry_transaction:
> >                       "%"PRIu32, new_target_memkb / 1024);
> >      libxl_dominfo_dispose(&ptr);
> >
> > +    rc = 0;
> >  out:
> >      if (!xs_transaction_end(ctx->xsh, t, abort_transaction)
> >          && !abort_transaction)
> > --
> > 1.9.1
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xen.org
> > http://lists.xen.org/xen-devel

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