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Chuck Lever says: ==================== net/handshake: anchor request lifetime to a pinned file reference handshake_nl_accept_doit() has accumulated four follow-on fixes since3b3009ea8a("net/handshake: Create a NETLINK service for handling handshake requests"):7ea9c1ec66,7798b59409,fe67b063f6, anddabac51b81. Each was a local refcount or NULL-check correction; none moved where the file reference is owned, and the same code keeps producing the same class of bug. Reworking the ownership is what breaks the pattern. For the duration of a request, sock->file has no single owner. Submit publishes the request without taking a file reference; accept_doit acquires one inside the handler, after the request has already left the pending list. The consumer can drop its own reference at any time, including the moment between handshake_req_next() popping the request and accept_doit reaching get_file(). The submit-side sock_hold() pins only struct sock; struct socket and sock->file remain under the consumer's control via the file descriptor. This series places the file reference under unambiguous ownership. handshake_req_submit() pins it on the request and completion or cancel drops it (patches 4-5); the submit-side sock_hold() then becomes redundant, and dropping it also closes a publish-before-pin race the late sock_hold itself opened (patch 6). The handshake_complete() API and its consumers move to a uniform negative-errno sign convention (patch 3), with the matching sign correction in nvme-tcp (patch 2). Patch 1 hardens hn_lock for BH context, the netns-exit drain fix builds on the new file-pin infrastructure (patch 8), and new KUnit file-count assertions verify the refcount contract (patch 7). Three things in this restructuring want a careful look. In handshake_complete(), the fput() of the request's file reference has to come after hp_done() -- fput() can transitively run handshake_sk_destruct() and free the request, so the patch stashes hr_file in a local first. handshake_sk_destruct() itself is kept on purpose: it owns rhashtable removal and kfree, and remains the backstop if a consumer path bypasses handshake_complete() entirely. Third, handshake_req_next() now returns its request with an extra get_file() held under hn_lock; accept_doit must consume that reference (FD_PREPARE on success, explicit fput on the fdf.err path), and any future caller has to honor the same contract. v2: https://patch.msgid.link/20260521-handshake-file-pin-v2-0-b9dadc472840@oracle.com v1: https://patch.msgid.link/20260518-handshake-file-pin-v1-0-4bbcb7e62fda@oracle.com ==================== Link: https://patch.msgid.link/20260525-handshake-file-pin-v3-0-66c616906ead@oracle.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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