Re: [Qemu-devel] [PATCH v3 0/5] Automatic RCU read unlock

[Paolo Bonzini]

On 25/09/19 17:28, Dr. David Alan Gilbert wrote:
> * Paolo Bonzini (address@hidden) wrote:
>> On 25/09/19 15:13, Dr. David Alan Gilbert wrote:
>>> * Dr. David Alan Gilbert (git) (address@hidden) wrote:
>>>> From: "Dr. David Alan Gilbert" <address@hidden>
>>>>
>>>> This patch uses glib's g_auto mechanism to automatically free
>>>> rcu_read_lock's at the end of the block.  Given that humans
>>>> have a habit of forgetting an error path somewhere it's
>>>> best to leave it to the compiler.
>>>
>>> I've had to unqueue this - clang doesn't like the apparently unused
>>> auto variable; we need to find a way to make that happy.
>>
>> __attribute__((unused))?
> 
> I worry that if I do that, then it'll optimise it out.

It cannot, since the function passed to the cleanup attribute can have
side effects.

Paolo

> 
> Dave
> 
>> Paolo
>>
>>> Dave
>>>
>>>> v3
>>>>   Add block-head version of macro
>>>>   Rename
>>>>   Add docs
>>>>   Convert more cases using the block-head version
>>>>
>>>> Dr. David Alan Gilbert (5):
>>>>   rcu: Add automatically released rcu_read_lock variants
>>>>   migration: Fix missing rcu_read_unlock
>>>>   migration: Use automatic rcu_read unlock in ram.c
>>>>   migration: Use automatic rcu_read unlock in rdma.c
>>>>   rcu: Use automatic rc_read unlock in core memory/exec code
>>>>
>>>>  docs/devel/rcu.txt      |  16 +++
>>>>  exec.c                  | 120 +++++++---------
>>>>  include/exec/ram_addr.h | 138 +++++++++----------
>>>>  include/qemu/rcu.h      |  25 ++++
>>>>  memory.c                |  15 +-
>>>>  migration/ram.c         | 295 +++++++++++++++++++---------------------
>>>>  migration/rdma.c        |  57 ++------
>>>>  7 files changed, 310 insertions(+), 356 deletions(-)
>>>>
>>>> -- 
>>>> 2.21.0
>>>>
>>>>
>>> --
>>> Dr. David Alan Gilbert / address@hidden / Manchester, UK
>>>
>>
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK
>