Closed Bug 1212308 Opened 9 years ago Closed 8 years ago

Possible issue with nested intr messages.

Categories

(Core :: IPC, defect)

Product:
Core
Component:
IPC
Platform:
All
Windows
Type:
defect
Priority:
Not set
Severity:
normal

Tracking

()

Status:
RESOLVED INVALID

People

(Reporter: bobowen, Unassigned)

Details

While looking into bug 1209464, I found what looked like a potential problem with nested intr messages.

Aaron found that it was a different bug that was causing the nested intr messages in the first place.
But as we seem to have the machinery set up for nested intr messages, maybe the problem I was seeing could happen in different circumstances.

In summary:
If we have the following:
* nested intr messages in the parent
* a sync message from the child
* all the replies for the intr and the sync request come into the parent's pending messages before the intr wait event is notified

Then if the last intr reply (i.e. the one we are waiting for) is before the sync request, then the reply is processed and we end up in the wait loop for previous intr, but nothing will notify the event, unless we get a message in from something else.

Bug 1209464 comment 7 to 10 have the details with links.
This may be nothing as the original bug has a fix, but Jim thought you might want to take a look at it.
Flags: needinfo?(wmccloskey)
From looking at this a bit more I suspect that the nesting will never happen at this part of the loop any more, but I'm not sure.

Either way round I think the idea in bug 1209464 comment 10 might still be a good one.
Hi Bob,
I've looked at this bug several times since you filed it. Each time I didn't understand it and I got distracted. Can you try to explain it a little more if you still remember? What I don't understand is how the nesting of the interrupt messages works. Can you describe a concrete situation showing which side sent each message and reply?
Thanks,
Bill
Flags: needinfo?(wmccloskey) → needinfo?(bobowen.code)
I'll need to remember the details myself, but yes I'll try and explain this better. :-)
We spoke about this in London and it looks like this is not an issue.
Status: NEW → RESOLVED
Closed: 8 years ago
Flags: needinfo?(bobowencode)
Resolution: --- → INVALID
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