Date: Sat, 15 Mar 2025 01:48:11 +0000 From: bugzilla-noreply@freebsd.org To: net@FreeBSD.org Subject: [Bug 137145] [mbuf] Reference count computing isn't correct when more than one threads call function m_copypacket Message-ID: <bug-137145-7501-S3MmrJaMSf@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-137145-7501@https.bugs.freebsd.org/bugzilla/> References: <bug-137145-7501@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=137145 Zhenlei Huang <zlei@FreeBSD.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |glebius@FreeBSD.org, | |zlei@FreeBSD.org --- Comment #8 from Zhenlei Huang <zlei@FreeBSD.org> --- Gleb changed some logic of mb_dupcl(), the patch should be rebased. I think we still risk concurrent mb_dupcl(). ``` /* See if this is the mbuf that holds the embedded refcount. */ if (m->m_ext.ext_flags & EXT_FLAG_EMBREF) { refcnt = n->m_ext.ext_cnt = &m->m_ext.ext_count; n->m_ext.ext_flags &= ~EXT_FLAG_EMBREF; } else { KASSERT(m->m_ext.ext_cnt != NULL, ("%s: no refcounting pointer on %p", __func__, m)); refcnt = m->m_ext.ext_cnt; } if (*refcnt == 1) *refcnt += 1; /* XXX_ZL possible to lose update on concurrent mb_dupcl() */ else atomic_add_int(refcnt, 1); ``` also CC @Gleb -- You are receiving this mail because: You are the assignee for the bug.
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