I'm not planning to review this patch, but could you please reformat
the commit message in a more standard way? I.E. something like:
poll-loop: <short description>\n
\n
<longer description>
The current formatting doesn't play nicely with git send email.
Ethan
On Fri, Dec 6, 2013 at 4:41 PM, Linda Sun <l...@vmware.com> wrote:
> Can you elaborate which cases have duplicate fds?
>
> I've already used closesocket instead of close handle for sockets. I'll send
> a separate patch with the stream related changes. E.g. Replace read/write on
> socket with send/recv.
>
> Linda
> ----- Original Message -----
> From: Eitan Eliahu <elia...@vmware.com>
> To: Ben Pfaff <b...@nicira.com>
> Cc: dev@openvswitch.org, Linda Sun <l...@vmware.com>
> Sent: Fri, 06 Dec 2013 16:18:51 -0800 (PST)
> Subject: Re: [ovs-dev] [PATCH] Use WaitForMultipleObjects for polling on
> windows. This works on all kinds of objects, e.g. sockets, files, especially
> ioctl calls to the kernel. One additional paramater is passed down in
> poll_fd_wait() to help WaitForMultipleObjects. latch is signaled with event,
> to be waited/polled by WaitForMultipleObjects() as well.
>
>
> Ben and Linda,
> It seems that the first two comments could be addressed (by removing NULL
> events and duplicates handles.
>
> In regards to the third comments, if these handles are Sockets (which I
> believe they are) these handles should never be closed by calling
> CloseHandle(). For these socket handles closesocket() should be used and
> therefore the resources associated with these handles will be freed and
> WaitForMultipleObjects will return with an error.
>
> Thanks,
> Eitan
>
>
>
> ----- Original Message -----
> From: "Ben Pfaff" <b...@nicira.com>
> To: "Linda Sun" <l...@vmware.com>
> Cc: dev@openvswitch.org
> Sent: Friday, December 6, 2013 3:57:03 PM
> Subject: Re: [ovs-dev] [PATCH] Use WaitForMultipleObjects for polling on
> windows. This works on all kinds of objects, e.g. sockets, files, especially
> ioctl calls to the kernel. One additional paramater is passed down in
> poll_fd_wait() to help WaitForMultipleObjects. latch is signaled with event,
> to be waited/polled by WaitForMultipleObjects() as well.
>
> On Fri, Dec 06, 2013 at 02:47:29PM -0800, Linda Sun wrote:
>> Signed-off-by: Linda Sun <l...@vmware.com>
>
> Hi Linda. Thanks for sending this along so that we can start figuring
> out how to work Windows into the poll loop.
>
> Looking at the documentation for WaitForMultipleObjects, I see a few
> possible issues.
>
> One is that it looks like we add a lot of null pointers to the wevents
> array (most of the poll_fd_wait() calls pass NULL). I don't see
> documentation for what WaitForMultipleObjects does with null pointers.
>
> WaitForMultipleObjects also forbids duplicates in its handles array.
> OVS calls poll with duplicates sometimes.
>
> WaitForMultipleObjects documentation says: "If one of these handles is
> closed while the wait is still pending, the function's behavior is
> undefined." OVS might sometimes close a file descriptor from one
> thread that some other thread is waiting for, since Unix has
> well-defined semantics for that. I'm not sure how to audit the code
> for this, or what the consequences for getting it wrong are.
> ("Undefined" sounds bad, but what happens in practice?)
>
> Thanks,
>
> Ben.
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