Fix a race between VBP_Remove() and vbp_thread() #3957
Merged
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
Suppose the following happens: vbp_task() finishes with vt->running = 0 and a heap insert. The vbp_cond is signaled under the lock, but now instead of vbp_thread() waking up first, VBP_Remove() gets the lock and reaches assert(vt->heap_idx == VBH_NOIDX) before the racing vbp_thread() deleted the heap. This is unlikely to happen with static backends, because for those, the probe is stopped via the vcl temperature before they get removed. Fixes nigoroll/libvmod-dynamic#100
nigoroll
force-pushed
the
dynamic100_vbp_remove_race
branch
from
9cda30a
to
6a3775f
Compare
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Outdated suggestions cannot be applied.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.
Suppose the following happens:
vbp_task()finishes withvt->running = 0and a heap insert. Thevbp_condis signaled under the lock, but now instead ofvbp_thread()waking up first,VBP_Remove()gets the lock and reachesassert(vt->heap_idx == VBH_NOIDX);before the racingvbp_thread()deleted the heap.This is unlikely to happen with static backends, because for those, the probe is stopped via the vcl temperature before they get removed.
Fixes nigoroll/libvmod-dynamic#100