cancelIo fix - cancellation sqe should be sent to the same ring as the original sqe

[qkrorlqr]

Otherwise cancellation returns ENOENT

ut added

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[Copilot]

Pull request overview

This PR fixes cross-fiber I/O cancellation with io_uring by ensuring the cancel SQE is submitted to the same per-CPU ring that originally holds the operation’s SQE, preventing -ENOENT cancels that can leave waiters blocked indefinitely.

Changes:

• Track which processor/ring an IoFuture was submitted to (IoFuture::submitProcessor).
• Route cancelIo() submissions to the recorded ring and, when cancelling remotely, force-submit and wake the target processor thread.
• Add a regression test that cancels a POLL_ADD from a different fiber (likely on a different CPU due to work-stealing).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
src/fibers/fiber.cpp	Records SQE submit ring and routes cancel SQEs to the correct per-CPU io_uring ring.
include/silk/fibers/fiber.h	Extends IoFuture with submitProcessor to support correct cancel routing.
src/fibers/tests/fiber-test.cpp	Adds a cross-fiber cancellation regression test for poll()/cancel().

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.