Master unbusy race #2986
Merged
Master unbusy race #2986
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
When an object is ready for delivery, HSH_Unbusy was called before calling ObjSetState([BOS_STREAM|BOS_FINISHED]). The HSH_Unbusy() call does the waitinglist rushing, but HSH_Lookup() wanted to look at the boc->state and if BOS_STREAM had been reached. This could cause requests woken to find that the stream state still hadn't been reached (ObjSetState still hadn't executed), and go back on the waitinglist. To fix this, this patch reverts commit 0375791, and goes back to considering OC_F_BUSY as the gate keeper for HSH_Lookup. This eliminates the race, because HSH_Unbusy and HSH_Lookup then uses the same mutex. That change opens up the possiblity that req code after HSH_Lookup() sees an object that has not yet reached BOS_STREAM. In order to not have to add new ObjWaitState() calls (with the additional locking cost that would bring) to wait for BOS_STREAM, the order of events is changed throughout, and calls ObjSetState([BOS_STREAM|BOS_FINISHED]) before HSH_Unbusy(). That way, an object returned from HSH_Lookup() is guaranteed to be at least BOS_STREAM.
This reverts some of the previous attempts to get these test cases stable, as those attempts actually prevented the testing of the desired code paths. Also make the test cases wait until the required requests are on the waitinglist before continuing.
|
Looks good to me and passes mild torture on 32&64 bit FreeBSD. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Resolve race on waitinglist rushing between OC_F_BUSY and boc->state …
When an object is ready for delivery, HSH_Unbusy was called before calling
ObjSetState([BOS_STREAM|BOS_FINISHED]). The HSH_Unbusy() call does the
waitinglist rushing, but HSH_Lookup() wanted to look at the boc->state and
if BOS_STREAM had been reached. This could cause requests woken to find
that the stream state still hadn't been reached (ObjSetState still hadn't
executed), and go back on the waitinglist.
To fix this, this patch reverts commit 0375791, and goes back to considering
OC_F_BUSY as the gate keeper for HSH_Lookup. This eliminates the race,
because HSH_Unbusy and HSH_Lookup then uses the same mutex.
That change opens up the possiblity that req code after HSH_Lookup() sees
an object that has not yet reached BOS_STREAM. In order to not have to add
new ObjWaitState() calls (with the additional locking cost that would
bring) to wait for BOS_STREAM, the order of events is changed throughout,
and calls ObjSetState([BOS_STREAM|BOS_FINISHED]) before HSH_Unbusy(). That
way, an object returned from HSH_Lookup() is guaranteed to be at least
BOS_STREAM.