Date: Sat, 20 Dec 2014 22:12:04 +0000 (UTC) From: Gleb Smirnoff <glebius@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r275968 - head/sys/kern Message-ID: <201412202212.sBKMC4FI089033@svn.freebsd.org>
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Author: glebius Date: Sat Dec 20 22:12:04 2014 New Revision: 275968 URL: https://svnweb.freebsd.org/changeset/base/275968 Log: Revert r274494, r274712, r275955 and provide extra comments explaining why there could appear a zero-sized mbufs in socket buffers. A proper fix would be to divorce record socket buffers and stream socket buffers, and divorce pru_send that accepts normal data from pru_send that accepts control data. Modified: head/sys/kern/uipc_sockbuf.c head/sys/kern/uipc_socket.c Modified: head/sys/kern/uipc_sockbuf.c ============================================================================== --- head/sys/kern/uipc_sockbuf.c Sat Dec 20 21:17:28 2014 (r275967) +++ head/sys/kern/uipc_sockbuf.c Sat Dec 20 22:12:04 2014 (r275968) @@ -640,9 +640,6 @@ sbappendstream_locked(struct sockbuf *sb { SOCKBUF_LOCK_ASSERT(sb); - if (m == NULL) - return; - KASSERT(m->m_nextpkt == NULL,("sbappendstream 0")); KASSERT(sb->sb_mb == sb->sb_lastrecord,("sbappendstream 1")); @@ -1065,6 +1062,21 @@ sbcut_internal(struct sockbuf *sb, int l m = n; } } + /* + * Free any zero-length mbufs from the buffer. + * For SOCK_DGRAM sockets such mbufs represent empty records. + * XXX: For SOCK_STREAM sockets such mbufs can appear in the buffer, + * when sosend_generic() needs to send only control data. + */ + while (m && m->m_len == 0) { + struct mbuf *n; + + sbfree(sb, m); + n = m->m_next; + m->m_next = mfree; + mfree = m; + m = n; + } if (m) { sb->sb_mb = m; m->m_nextpkt = next; Modified: head/sys/kern/uipc_socket.c ============================================================================== --- head/sys/kern/uipc_socket.c Sat Dec 20 21:17:28 2014 (r275967) +++ head/sys/kern/uipc_socket.c Sat Dec 20 22:12:04 2014 (r275968) @@ -1310,11 +1310,14 @@ restart: resid = 0; if (flags & MSG_EOR) top->m_flags |= M_EOR; - } else if (resid > 0) { + } else { /* * Copy the data from userland into a mbuf - * chain. If no data is to be copied in, - * a single empty mbuf is returned. + * chain. If resid is 0, which can happen + * only if we have control to send, then + * a single empty mbuf is returned. This + * is a workaround to prevent protocol send + * methods to panic. */ top = m_uiotombuf(uio, M_WAITOK, space, (atomic ? max_hdr : 0),
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