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