Date: Fri, 01 Dec 2000 16:01:41 -0800 From: David Greenman <dg@root.com> To: Andrew Gallatin <gallatin@cs.duke.edu>, Bosko Milekic <bmilekic@technokratis.com>, "Kenneth D. Merry" <ken@kdm.org>, arch@FreeBSD.ORG, alfred@FreeBSD.ORG Subject: Re: zero copy code review Message-ID: <200012020001.QAA14320@implode.root.com> In-Reply-To: Your message of "Fri, 01 Dec 2000 15:26:19 PST." <200012012326.PAA14154@implode.root.com>
next in thread | previous in thread | raw e-mail | index | archive | help
>> > In your code, you do deal with the possibility of the MGETHDR >> > returning NULL (you check for it) and you set ENOBUFS in that case and >> > jump to the "errorpath" label. But, before using MGETHDR, you allocate an >> > sf_buf (in sf) and it just so happens that the code beyond "errorpath" >> > does not take care of freeing the sf_buf you allocated before even >> > trying to allocate the mbuf. >> >>I see your point. This was copied, (bug for bug ;-), from sendfile itself. >>Look at line 1700 or so of kern/uipc_syscalls.c.. This bug should >>probaby be fixed there too.. > > Oops. The original assumption (and code that I wrote) was that M_WAIT >_cannot_ return a NULL pointer. This was changed in FreeBSD recently, and >as you mentioned, the code added in rev 1.65 that now checks for it in >sendfile doesn't do complete cleanup in this case. It definately should >be fixed so that the sf_buf is freed as well. Followup...the attached patch should fix the problem. -DG David Greenman Co-founder, The FreeBSD Project - http://www.freebsd.org President, TeraSolutions, Inc. - http://www.terasolutions.com Pave the road of life with opportunities. Index: uipc_syscalls.c =================================================================== RCS file: /home/ncvs/src/sys/kern/uipc_syscalls.c,v retrieving revision 1.65.2.3 diff -c -r1.65.2.3 uipc_syscalls.c *** uipc_syscalls.c 2000/08/16 19:20:31 1.65.2.3 --- uipc_syscalls.c 2000/12/01 23:54:19 *************** *** 1628,1633 **** --- 1630,1636 ---- MGETHDR(m, M_WAIT, MT_DATA); if (m == NULL) { error = ENOBUFS; + sf_buf_free((void *)sf->kva, PAGE_SIZE); goto done; } m->m_ext.ext_free = sf_buf_free; To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200012020001.QAA14320>