On Tue, 19 Oct 2010, Christoph Egger wrote:
> On Monday 18 October 2010 14:50:35 Christoph Egger wrote:
> > Hi!
> >
> > I cannot start a guest with 'xl create' due to an endless loop in libxl.c,
> > function libxl__get_free_memory_slack():
> >
> > There is this code snippet:
> >
> > retry:
> > free_mem_slack_s = libxl__xs_read(gc, XBT_NULL, free_mem_slack_path);
> > if (!free_mem_slack_s) {
> > rc = libxl__fill_dom0_memory_info(gc, &target_memkb);
> > if (rc < 0)
> > return rc;
> > goto retry;
> > } else {
> >
> >
> > libxl__xs_read() returns 0 and libxl__fill_dom0_memory_info() also returns
> > 0. So there's a loop of retries.
>
> Attached patch fixes the endless loop.
>
> Signed-off-by: Christoph Egger <Christoph.Egger@xxxxxxx>
thanks for the patch but this cannot possibly be the right fix:
diff -r 9d8d6b93114e tools/libxl/libxl.c
--- a/tools/libxl/libxl.c Mon Oct 18 15:24:39 2010 +0200
+++ b/tools/libxl/libxl.c Tue Oct 19 10:29:00 2010 +0200
@@ -2836,7 +2836,7 @@ retry:
free_mem_slack_s = libxl__xs_read(gc, XBT_NULL, free_mem_slack_path);
if (!free_mem_slack_s) {
rc = libxl__fill_dom0_memory_info(gc, &target_memkb);
- if (rc < 0)
+ if (rc <= 0)
return rc;
goto retry;
} else {
the idea is that libxl__fill_dom0_memory_info should fill the missing
informations in xenstore so that we can go ahead and try to read them
again and the second time should be successful.
Libxl__fill_dom0_memory_info returns 0 on success, so it is correct to
goto retry in that case.
The bug must be in libxl__fill_dom0_memory_info that doesn't return
error when it should.
Does the appended patch works for you?
---
diff -r 00b92112b055 tools/libxl/libxl.c
--- a/tools/libxl/libxl.c Wed Oct 20 17:26:51 2010 +0100
+++ b/tools/libxl/libxl.c Thu Oct 21 15:08:29 2010 +0100
@@ -2793,11 +2793,11 @@ retry_transaction:
rc = libxl_domain_info(ctx, &info, 0);
if (rc < 0)
- return rc;
+ goto out;
rc = libxl_get_physinfo(ctx, &physinfo);
if (rc < 0)
- return rc;
+ goto out;
libxl__xs_write(gc, t, target_path, "%"PRIu32,
(uint32_t) info.current_memkb);
@@ -2816,9 +2816,12 @@ retry_transaction:
rc = 0;
out:
- if (!xs_transaction_end(ctx->xsh, t, 0))
+ if (!xs_transaction_end(ctx->xsh, t, 0)) {
if (errno == EAGAIN)
goto retry_transaction;
+ else
+ rc = ERROR_FAIL;
+ }
return rc;
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