From: Claudio Jeker Subject: Re: ddb mbuf chains To: Alexander Bluhm Cc: tech@openbsd.org Date: Thu, 5 Sep 2024 07:20:42 +0200 On Thu, Sep 05, 2024 at 12:38:41AM +0200, Alexander Bluhm wrote: > On Thu, Aug 29, 2024 at 09:15:54PM +0200, Alexander Bluhm wrote: > > On Wed, Aug 28, 2024 at 10:43:16PM +0200, Alexander Bluhm wrote: > > > I want to print the layout of mbuf chains in ddb. For debugging > > > hardware offloading, DMA requirements and bounce buffers, I need > > > to know the layout of the mbuf chain by m_next and m_nextpkt pointer. > > > So I implemented /c and /p modifiers for ddb show mbuf. > > > > > > ddb> show mbuf /pc 0xfffffd8006fd5100 > > > > Additionally we can print mbuf type and offset. Then a UDP receive > > socket buffer looks like this: > > > > ++- mbuf 0xfffffd806dcddd00, nam, off 0, len 16 > > |+- mbuf 0xfffffd806dcddf00, dat, off 52, len 1472, pktlen 2049, clsize 2048 > > |+- mbuf 0xfffffd806dcdd400, dat, off 44, len 577, clsize 2048 > > |\- total chain 3, len 2065, size 4320 > > ++- mbuf 0xfffffd806dcdde00, nam, off 0, len 16 > > |+- mbuf 0xfffffd806dcdd800, dat, off 52, len 4, pktlen 4, clsize 2048 > > |\- total chain 2, len 20, size 2272 > > \-- total packets 2 > > A m->m_type >= 0 check was missing. One could wonder why m_type is a short? > > ok? > > Anyone? OK claudio@ > bluhm > > > Index: sys/ddb/db_command.c > =================================================================== > RCS file: /data/mirror/openbsd/cvs/src/sys/ddb/db_command.c,v > diff -u -p -r1.101 db_command.c > --- sys/ddb/db_command.c 13 May 2024 01:15:50 -0000 1.101 > +++ sys/ddb/db_command.c 29 Aug 2024 17:57:18 -0000 > @@ -340,7 +340,15 @@ db_malloc_print_cmd(db_expr_t addr, int > void > db_mbuf_print_cmd(db_expr_t addr, int have_addr, db_expr_t count, char *modif) > { > - m_print((void *)addr, db_printf); > + if ((modif[0] == 'c' && modif[1] == 'p') || > + (modif[0] == 'p' && modif[1] == 'c')) > + m_print_packet((void *)addr, 1, db_printf); > + else if (modif[0] == 'c') > + m_print_chain((void *)addr, 0, db_printf); > + else if (modif[0] == 'p') > + m_print_packet((void *)addr, 0, db_printf); > + else > + m_print((void *)addr, db_printf); > } > > void > Index: sys/ddb/db_interface.h > =================================================================== > RCS file: /data/mirror/openbsd/cvs/src/sys/ddb/db_interface.h,v > diff -u -p -r1.27 db_interface.h > --- sys/ddb/db_interface.h 3 Feb 2024 18:51:58 -0000 1.27 > +++ sys/ddb/db_interface.h 29 Aug 2024 17:57:18 -0000 > @@ -61,6 +61,8 @@ void db_show_all_pools(db_expr_t, int, d > > /* kern/uipc_mbuf.c */ > void m_print(void *, int (*)(const char *, ...)); > +void m_print_chain(void *, int, int (*)(const char *, ...)); > +void m_print_packet(void *, int, int (*)(const char *, ...)); > > /* kern/uipc_socket.c */ > void so_print(void *, int (*)(const char *, ...)); > Index: sys/kern/uipc_mbuf.c > =================================================================== > RCS file: /data/mirror/openbsd/cvs/src/sys/kern/uipc_mbuf.c,v > diff -u -p -r1.291 uipc_mbuf.c > --- sys/kern/uipc_mbuf.c 29 Aug 2024 10:44:40 -0000 1.291 > +++ sys/kern/uipc_mbuf.c 29 Aug 2024 19:18:25 -0000 > @@ -1533,6 +1533,80 @@ m_print(void *v, > > } > } > + > +const char *m_types[MT_NTYPES] = { > + "fre", > + "dat", > + "hdr", > + "nam", > + "opt", > + "ftb", > + "ctl", > + "oob", > +}; > + > +void > +m_print_chain(void *v, int deep, > + int (*pr)(const char *, ...) __attribute__((__format__(__kprintf__,1,2)))) > +{ > + struct mbuf *m; > + const char *indent = deep ? "++-" : "-+-"; > + size_t chain = 0, len = 0, size = 0; > + > + for (m = v; m != NULL; m = m->m_next) { > + const char *type; > + > + chain++; > + len += m->m_len; > + size += M_SIZE(m); > + type = (m->m_type >= 0 && m->m_type < MT_NTYPES) ? > + m_types[m->m_type] : "???"; > + (*pr)("%s mbuf %p, %s, off %zd, len %u", indent, m, type, > + m->m_data - M_DATABUF(m), m->m_len); > + if (m->m_flags & M_PKTHDR) > + (*pr)(", pktlen %d", m->m_pkthdr.len); > + if (m->m_flags & M_EXT) > + (*pr)(", clsize %u", m->m_ext.ext_size); > + (*pr)("\n"); > + indent = deep ? "|+-" : " +-"; > + } > + indent = deep ? "|\\-" : " \\-"; > + if (v != NULL) { > + (*pr)("%s total chain %zu, len %zu, size %zu\n", > + indent, chain, len, size); > + } > +} > + > +void > +m_print_packet(void *v, int deep, > + int (*pr)(const char *, ...) __attribute__((__format__(__kprintf__,1,2)))) > +{ > + struct mbuf *m, *n; > + const char *indent = "+--"; > + size_t pkts = 0; > + > + for (m = v; m != NULL; m = m->m_nextpkt) { > + size_t chain = 0, len = 0, size = 0; > + > + pkts++; > + if (deep) { > + m_print_chain(m, deep, pr); > + continue; > + } > + for (n = m; n != NULL; n = n->m_next) { > + chain++; > + len += n->m_len; > + size += M_SIZE(n); > + } > + (*pr)("%s mbuf %p, chain %zu", indent, m, chain); > + if (m->m_flags & M_PKTHDR) > + (*pr)(", pktlen %d", m->m_pkthdr.len); > + (*pr)(", len %zu, size %zu\n", len, size); > + } > + indent = "\\--"; > + if (v != NULL) > + (*pr)("%s total packets %zu\n", indent, pkts); > +} > #endif > > /* > Index: share/man/man4/ddb.4 > =================================================================== > RCS file: /data/mirror/openbsd/cvs/src/share/man/man4/ddb.4,v > diff -u -p -r1.107 ddb.4 > --- share/man/man4/ddb.4 5 Feb 2024 21:33:00 -0000 1.107 > +++ share/man/man4/ddb.4 28 Aug 2024 19:51:26 -0000 > @@ -658,7 +658,11 @@ If the > .Cm /f > modifier is specified, the complete map is printed. > .\" -------------------- > -.It Ic show mbuf Ar addr > +.It Xo > +.Ic show mbuf > +.Op Cm /cp > +.Ar addr > +.Xc > Prints the > .Vt struct mbuf > header at > @@ -668,6 +672,13 @@ Depending on the mbuf flags > and > .Vt struct m_ext > are printed as well. > +If the > +.Cm /c > +modifier is specified, print the mbuf chain linked with the m_next > +pointer. > +.Cm /p > +does the same using m_nextpkt. > +Both can be combined. > .\" -------------------- > .It Xo > .Ic show mount > -- :wq Claudio