Date: Sat, 2 May 2020 22:44:24 +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: r360570 - head/sys/kern Message-ID: <202005022244.042MiO0K041897@repo.freebsd.org>
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Author: glebius Date: Sat May 2 22:44:23 2020 New Revision: 360570 URL: https://svnweb.freebsd.org/changeset/base/360570 Log: In mb_unmapped_compress() we don't need mbuf structure to keep data, but we need buffer of MLEN bytes. This isn't just a simplification, but important fixup, because previous commit shrinked sizeof(struct mbuf) down below MSIZE, and instantiating an mbuf on stack no longer provides enough data. Reviewed by: gallatin Differential Revision: https://reviews.freebsd.org/D24598 Modified: head/sys/kern/kern_mbuf.c Modified: head/sys/kern/kern_mbuf.c ============================================================================== --- head/sys/kern/kern_mbuf.c Sat May 2 22:39:26 2020 (r360569) +++ head/sys/kern/kern_mbuf.c Sat May 2 22:44:23 2020 (r360570) @@ -853,7 +853,7 @@ int mb_unmapped_compress(struct mbuf *m) { volatile u_int *refcnt; - struct mbuf m_temp; + char buf[MLEN]; /* * Assert that 'm' does not have a packet header. If 'm' had @@ -876,12 +876,8 @@ mb_unmapped_compress(struct mbuf *m) if (*refcnt != 1) return (EBUSY); - m_init(&m_temp, M_NOWAIT, MT_DATA, 0); + m_copydata(m, 0, m->m_len, buf); - /* copy data out of old mbuf */ - m_copydata(m, 0, m->m_len, mtod(&m_temp, char *)); - m_temp.m_len = m->m_len; - /* Free the backing pages. */ m->m_ext.ext_free(m); @@ -889,8 +885,8 @@ mb_unmapped_compress(struct mbuf *m) m->m_flags &= ~(M_EXT | M_RDONLY | M_NOMAP); m->m_data = m->m_dat; - /* copy data back into m */ - m_copydata(&m_temp, 0, m_temp.m_len, mtod(m, char *)); + /* Copy data back into m. */ + bcopy(buf, mtod(m, char *), m->m_len); return (0); }
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