[libvirt] [PATCH 1/6] port allocator: make used port bitmap global

[Michal Privoznik]

On 12/20/2017 07:35 AM, Nikolay Shirokovskiy wrote:
> Host tcp4/tcp6 ports is a global resource thus we need to make
> port accounting also global or we have issues described in [1] when
> port allocator ranges of different instances are overlapped (which
> is by default for qemu for example).
> 
> Let's have only one global port allocator object that take care
> of the entire ports range (0 - 65535) and introduce port range object
> for clients to specify desired auto allocation band.
> 
> [1] https://www.redhat.com/archives/libvir-list/2017-December/msg00600.html
> ---
>  src/bhyve/bhyve_driver.c       |   4 +-
>  src/bhyve/bhyve_utils.h        |   2 +-
>  src/libvirt_private.syms       |   3 +-
>  src/libxl/libxl_conf.c         |   8 +--
>  src/libxl/libxl_conf.h         |   8 +--
>  src/libxl/libxl_driver.c       |  18 +++---
>  src/qemu/qemu_conf.h           |   6 +-
>  src/qemu/qemu_driver.c         |  30 +++++-----
>  src/util/virportallocator.c    | 125 ++++++++++++++++++++++++++++-------------
>  src/util/virportallocator.h    |  20 ++++---
>  tests/bhyvexml2argvtest.c      |   6 +-
>  tests/libxlxml2domconfigtest.c |   8 +--
>  tests/virportallocatortest.c   |  48 ++++++++++------
>  13 files changed, 175 insertions(+), 111 deletions(-)
> 

> diff --git a/src/util/virportallocator.c b/src/util/virportallocator.c
> index fcd4f74..cd64356 100644
> --- a/src/util/virportallocator.c
> +++ b/src/util/virportallocator.c
> @@ -35,10 +35,14 @@
>  
>  #define VIR_FROM_THIS VIR_FROM_NONE
>  
> +typedef struct _virPortAllocator virPortAllocator;
> +typedef virPortAllocator *virPortAllocatorPtr;
>  struct _virPortAllocator {
>      virObjectLockable parent;
>      virBitmapPtr bitmap;
> +};
>  
> +struct _virPortRange {
>      char *name;
>  
>      unsigned short start;
> @@ -48,6 +52,7 @@ struct _virPortAllocator {
>  };
>  
>  static virClassPtr virPortAllocatorClass;
> +static virPortAllocatorPtr virPortAllocatorInstance;

I wonder if this is the way to go. I mean, this virPortAllocatorInstance
is going to be a global variable that will never be freed (even if we
wanted to). I mean, if virPortRange had a pointer to virPortAllocator
and ref/unref it in virPortRangeNew() and virPortRangeFree() then we're
good. To break this down, leave the global variable, have
virPortRangeNew() call:

virPortRangePtr
virPortRangeNew(const char *name,
                unsigned short start,
                unsigned short end,
                unsigned int flags)
{

  virPortAllocatorInitialize();

  range->pa = virObjectRef(virPortAllocatorInstance);
  ...
}

Also, virPortAllocatorDispose() would set the virPortAllocatorInstance
pointer to NULL.

This is also the root cause of libxlxml2domconfigtest failing for me. So
even though you construct virPortRange fresh new for each
testCompareXMLToDomConfig() run, the underlying virPortAllocatorInstance
stays through different runs. So a port allocated in one run stays
allocated in the second run too. Yeah, virPortAllocatorRelease() is
never called from this test.


Oh, and one BIG problem although complier doesn't complain: there
already is virPortRange in src/util/virsocketaddr.h and it looks
slightly different. So you need to rename your type.
virPortAllocatorRange maybe?


Michal