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  • Anton Anton anjo
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  1. Aug 04, 2011
    • Amit Shah's avatar
      balloon: Separate out stat and balloon handling · 30fb2ca6
      Amit Shah authored 
      
Passing on '0' as ballooning target to indicate retrieval of stats is
bad API.  It also makes 'balloon 0' in the monitor cause a segfault.
Have two different functions handle the different functionality instead.

Detailed explanation from Markus's review:

1. do_info_balloon() is an info_async() method.  It receives a callback
   with argument, to be called exactly once (callback frees the
   argument).  It passes the callback via qemu_balloon_status() and
   indirectly through qemu_balloon_event to virtio_balloon_to_target().

   virtio_balloon_to_target() executes its balloon stats half.  It
   stores the callback in the device state.

   If it can't send a stats request, it resets stats and calls the
   callback right away.

   Else, it sends a stats request.  The device model runs the callback
   when it receives the answer.

   Works.

2. do_balloon() is a cmd_async() method.  It receives a callback with
   argument, to be called when the command completes.  do_balloon()
   calls it right before it succeeds.  Odd, but should work.

   Nevertheless, it passes the callback on via qemu_ballon() and
   indirectly through qemu_balloon_event to virtio_balloon_to_target().

   a. If the argument is non-zero, virtio_balloon_to_target() executes
      its balloon half, which doesn't use the callback in any way.

      Odd, but works.

   b. If the argument is zero, virtio_balloon_to_target() executes its
      balloon stats half, just like in 1.  It either calls the callback
      right away, or arranges for it to be called later.

      Thus, the callback runs twice: use after free and double free.

Test case: start with -S -device virtio-balloon, execute "balloon 0" in
human monitor.  Runs the callback first from virtio_balloon_to_target(),
then again from do_balloon().

Reported-by: default avatarMike Cao <bcao@redhat.com>
Signed-off-by: default avatarAmit Shah <amit.shah@redhat.com>
Reviewed-by: default avatarMarkus Armbruster <armbru@redhat.com>
      30fb2ca6
    • Amit Shah's avatar
      virtio-balloon: Separate status handling into separate function · dce911c7
      Amit Shah authored 
      
Separate out the code to retrieve balloon info from the code that sets
balloon values.

This will be used to separate the two callbacks from balloon.c and help
cope with 'balloon 0' on the monitor.  Currently, 'balloon 0' causes a
segfault in monitor_resume().

Signed-off-by: default avatarAmit Shah <amit.shah@redhat.com>
Reviewed-by: default avatarMarkus Armbruster <armbru@redhat.com>
      dce911c7
    • Amit Shah's avatar
      balloon: Simplify code flow · 182b9203
      Amit Shah authored 
      
Replace:
  if (foo) {
    ...
  } else {
    return 0;
  }

by

  if (!foo) {
    return 0;
  }
  ...

Signed-off-by: default avatarAmit Shah <amit.shah@redhat.com>
Reviewed-by: default avatarMarkus Armbruster <armbru@redhat.com>
      182b9203
    • Amit Shah's avatar
      balloon: Add braces around if statements · b80bc1dd
      Amit Shah authored 
      
Signed-off-by: default avatarAmit Shah <amit.shah@redhat.com>
Reviewed-by: default avatarMarkus Armbruster <armbru@redhat.com>
      b80bc1dd
    • Amit Shah's avatar
      balloon: Make functions, local vars static · 0a2a30d5
      Amit Shah authored 
      
balloon.h had function declarations for a couple of functions that are
local to balloon.c.  Make them static.

Drop the 'qemu_' prefix for balloon.c-local variables, and make them
static.

Signed-off-by: default avatarAmit Shah <amit.shah@redhat.com>
Reviewed-by: default avatarMarkus Armbruster <armbru@redhat.com>
      0a2a30d5
  3. Aug 03, 2011
  5. Aug 01, 2011
  7. Jul 31, 2011
  9. Jul 30, 2011
  11. Jul 29, 2011