[daandemeyer]

IORING_OP_CONNECT on a non-blocking AF_UNIX socket whose listener has a
full backlog retries the connect 128 times, then punts it to an io-wq
worker, and still completes with -EAGAIN. The new connect-backlog test
checks that the request completes with -EAGAIN without starting an io-wq
worker. It also checks that a blocking connect waits until accept()
makes room, and that a non-blocking TCP connect that gets -EINPROGRESS
waits for the handshake to complete.

The non-blocking case fails on kernels without the kernel patch
"io_uring/net: don't retry a non-blocking connect() that fails with
-EAGAIN".

---

git request-pull output:

The following changes since commit a33a770d8379978660036251e14710c6ee8a3d34:

  Merge branch 'ringbuf-read-fname-bound' of https://github.com/rootvector2/liburing (2026-05-28 06:43:37 -0600)

are available in the Git repository at:

  https://github.com/DaanDeMeyer/liburing connect-backlog

for you to fetch changes up to 220aa1eb5c568e04ef43f6e0dd4bd96eb63f14f7:

  test: add connect-backlog test (2026-10-27 14:56:58 +0100)

----------------------------------------------------------------
Daan De Meyer (1):
      test: add connect-backlog test

 test/Makefile          |   1 +
 test/connect-backlog.c | 444 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 445 insertions(+)
 create mode 100644 test/connect-backlog.c

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Fixes: https://github.com/axboe/liburing/issues/402
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[daandemeyer]

Might be a bit excessive to add a test for this, can always close this if it's too much

[axboe]

I think adding weird corner cases is the best use of a test case, I'll pull it in. Yes it's not the most important thing, but may as well check for it.