sock: optimise UDP sock_wfree() refcounting

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For non SOCK_USE_WRITE_QUEUE sockets, sock_wfree() (atomically) puts
->sk_wmem_alloc twice. It's needed to keep the socket alive while
calling ->sk_write_space() after the first put.

However, some sockets, such as UDP, are freed by RCU
(i.e. SOCK_RCU_FREE) and use already RCU-safe sock_def_write_space().
Carve a fast path for such sockets, put down all refs in one go before
calling sock_def_write_space() but guard the socket from being freed
by an RCU read section.

note: because TCP sockets are marked with SOCK_USE_WRITE_QUEUE it
doesn't add extra checks in its path.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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Pavel Begunkov 2022-04-28 11:58:18 +01:00 • committed by David S. Miller

parent 14bfee9b62

commit 052ada0968

1 changed files with 14 additions and 0 deletions

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net/core/sock.c

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