Date: Wed, 15 Jun 2011 20:34:41 +0000 (UTC) From: Mikolaj Golub <trociny@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org Subject: svn commit: r223119 - stable/8/sys/kern Message-ID: <201106152034.p5FKYfFR097295@svn.freebsd.org>
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Author: trociny Date: Wed Jun 15 20:34:40 2011 New Revision: 223119 URL: http://svn.freebsd.org/changeset/base/223119 Log: MFC r222454: 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 <simon@comsys.ntu-kpi.kiev.ua> Tested by: Andrey Simonenko <simon@comsys.ntu-kpi.kiev.ua> Reviewed by: rwatson Approved by: pjd (mentor) Modified: stable/8/sys/kern/uipc_socket.c Directory Properties: stable/8/sys/ (props changed) stable/8/sys/amd64/include/xen/ (props changed) stable/8/sys/cddl/contrib/opensolaris/ (props changed) stable/8/sys/contrib/dev/acpica/ (props changed) stable/8/sys/contrib/pf/ (props changed) Modified: stable/8/sys/kern/uipc_socket.c ============================================================================== --- stable/8/sys/kern/uipc_socket.c Wed Jun 15 19:53:08 2011 (r223118) +++ stable/8/sys/kern/uipc_socket.c Wed Jun 15 20:34:40 2011 (r223119) @@ -1836,10 +1836,16 @@ 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)
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