From 1dfa9ab8735324b683e437551bc3829f83c6e8f0 Mon Sep 17 00:00:00 2001 From: trociny Date: Sun, 29 May 2011 18:00:50 +0000 Subject: In soreceive_generic(), if MSG_WAITALL is set but the request is larger than the receive buffer, we have to receive in sections. When notifying the protocol that some data has been drained the lock is released for a moment. Returning we block waiting for the rest of data. There is a race, when data could arrive while the lock was released and then the connection stalls in sbwait. Fix this by checking for data before blocking and skip blocking if there are some. PR: kern/154504 Reported by: Andrey Simonenko Tested by: Andrey Simonenko Reviewed by: rwatson Approved by: kib (co-mentor) MFC after: 2 weeks --- sys/kern/uipc_socket.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'sys/kern/uipc_socket.c') diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c index 54a050f..3334fc2 100644 --- a/sys/kern/uipc_socket.c +++ b/sys/kern/uipc_socket.c @@ -1845,10 +1845,16 @@ dontblock: } SBLASTRECORDCHK(&so->so_rcv); SBLASTMBUFCHK(&so->so_rcv); - error = sbwait(&so->so_rcv); - if (error) { - SOCKBUF_UNLOCK(&so->so_rcv); - goto release; + /* + * We could receive some data while was notifying + * the protocol. Skip blocking in this case. + */ + if (so->so_rcv.sb_mb == NULL) { + error = sbwait(&so->so_rcv); + if (error) { + SOCKBUF_UNLOCK(&so->so_rcv); + goto release; + } } m = so->so_rcv.sb_mb; if (m != NULL) -- cgit v1.1