CVSROOT: /cvs
Module name: src
Changes by: m...@cvs.openbsd.org 2024/04/15 15:31:29
Modified files:
sys/kern : uipc_socket.c
Log message:
Don't take solock() in soreceive() for udp(4) sockets.
These sockets are not connection oriented, they don't call pru_rcvd(),
but they have splicing ability and they set `so_error'.
Splicing ability is the most problem. However, we can hold `sb_mtx'
around `ssp_socket' modifications together with solock(). So the
`sb_mtx' is pretty enough to isspiced() check in soreceive(). The
unlocked `so_sp' dereference is fine, because we set it only once for
the whole socket life-time and we do this before `ssp_socket'
assignment.
We also need to take sblock() before splice sockets, so the sosplice()
and soreceive() are both serialized. Since `sb_mtx' required to unsplice
sockets too, it also serializes somove() with soreceive() regardless on
somove() caller.
The sosplice() was reworked to accept standalone sblock() for udp(4)
sockets.
soreceive() performs unlocked `so_error' check and modification.
Previously, we have no ability to predict which concurrent soreceive()
or sosend() thread will fail and clean `so_error'. With this unlocked
access we could have sosend() and soreceive() threads which fails
together.
`so_error' stored to local `error2' variable because `so_error' could be
overwritten by concurrent sosend() thread.
Tested and ok bluhm
