[Qemu-devel] [PATCH] slirp: reorder include to fix FreeBSD build failure

[Qemu-devel] [PATCH] slirp: reorder include to fix FreeBSD build failure

[Ed Maste]

Signed-off-by: Ed Maste <emaste@freebsd.org>
---
The issue comes from slirp/mbuf.h #defining m_flags, which conflicts with
a header included via <semaphore.h> on FreeBSD.

I'm not sure exactly when this broke; I assume that it used to work because
something previously caused the conflicting header to be included earlier,
and that has now been removed.

 slirp/slirp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/slirp/slirp.c b/slirp/slirp.c
index 80b28ea..231afc8 100644
--- a/slirp/slirp.c
+++ b/slirp/slirp.c
@@ -24,8 +24,8 @@
 #include "qemu-common.h"
 #include "qemu/timer.h"
 #include "sysemu/char.h"
-#include "slirp.h"
 #include "hw/hw.h"
+#include "slirp.h"
 
 /* host loopback address */
 struct in_addr loopback_addr;
-- 
1.7.11.5

Re: [Qemu-devel] [Qemu-trivial] [PATCH] slirp: reorder include to fix FreeBSD build failure

[Michael Tokarev]

[-- Attachment #1: Type: text/plain, Size: 1732 bytes --]

13.07.2013 00:29, Ed Maste wrote:
> Signed-off-by: Ed Maste <emaste@freebsd.org>
> ---
> The issue comes from slirp/mbuf.h #defining m_flags, which conflicts with
> a header included via <semaphore.h> on FreeBSD.

Umgh.  How.. disgusting... :(

Here's the code in question.


/* header at beginning of each mbuf: */
struct m_hdr {
        struct  mbuf *mh_next;          /* Linked list of mbufs */
        struct  mbuf *mh_prev;
        struct  mbuf *mh_nextpkt;       /* Next packet in queue/record */
        struct  mbuf *mh_prevpkt; /* Flags aren't used in the output queue */
        int     mh_flags;         /* Misc flags */
...
};

struct mbuf {
        struct  m_hdr m_hdr;
        Slirp *slirp;
        bool    arp_requested;
...
};

#define m_next          m_hdr.mh_next
#define m_prev          m_hdr.mh_prev
#define m_nextpkt       m_hdr.mh_nextpkt
#define m_prevpkt       m_hdr.mh_prevpkt
#define m_flags         m_hdr.mh_flags
...

It looks to me that we should just get rid of all this.
struct m_hdr isn't used anywhere else so all its
members can be included directly into struct mbuf,
removing a good portion of those disgusting #defines.

Remaining:

struct mbuf {
        union M_dat {
                char    m_dat_[1]; /* ANSI don't like 0 sized arrays */
                char    *m_ext_;
        } M_dat;
};

#define m_dat           M_dat.m_dat_
#define m_ext           M_dat.m_ext_

This can be done by using an unnamed union, ie, by omitting
M_dat.

And since the code almost everywhere uses those m_* defines, it
is trivial to fix this for real.

Something like the attached.

Maybe we should get rid of the rest of indirections here too,
ifq_prev ifs_prev etc, but i'm not sure about these.

Thanks,

/mjt

[-- Attachment #2: slirp-remove-mbuf-m_hdr-m_dat-indirection.patch --]
[-- Type: text/x-patch, Size: 5606 bytes --]

>From ca96db1db67a6d244ce983450929a0c32c26a9cd Mon Sep 17 00:00:00 2001
From: Michael Tokarev <mjt@tls.msk.ru>
Date: Sat, 13 Jul 2013 13:10:05 +0400
Subject: [PATCH] slirp: remove mbuf(m_hdr,m_dat) indirection

Signed-off-By: Michael Tokarev <mjt@tls.msk.ru>
---
 slirp/mbuf.h     |   51 ++++++++++++++++++---------------------------------
 slirp/tcp_subr.c |   12 ++++++------
 2 files changed, 24 insertions(+), 39 deletions(-)

diff --git a/slirp/mbuf.h b/slirp/mbuf.h
index 3f3ab09..b144f1c 100644
--- a/slirp/mbuf.h
+++ b/slirp/mbuf.h
@@ -49,22 +49,6 @@
  * free the m_ext.  This is inefficient memory-wise, but who cares.
  */
 
-/* XXX should union some of these! */
-/* header at beginning of each mbuf: */
-struct m_hdr {
-	struct	mbuf *mh_next;		/* Linked list of mbufs */
-	struct	mbuf *mh_prev;
-	struct	mbuf *mh_nextpkt;	/* Next packet in queue/record */
-	struct	mbuf *mh_prevpkt; /* Flags aren't used in the output queue */
-	int	mh_flags;	  /* Misc flags */
-
-	int	mh_size;		/* Size of data */
-	struct	socket *mh_so;
-
-	caddr_t	mh_data;		/* Location of data */
-	int	mh_len;			/* Amount of data in this mbuf */
-};
-
 /*
  * How much room is in the mbuf, from m_data to the end of the mbuf
  */
@@ -80,29 +64,30 @@ struct m_hdr {
 #define M_TRAILINGSPACE M_FREEROOM
 
 struct mbuf {
-	struct	m_hdr m_hdr;
+	/* XXX should union some of these! */
+	/* header at beginning of each mbuf: */
+	struct	mbuf *m_next;		/* Linked list of mbufs */
+	struct	mbuf *m_prev;
+	struct	mbuf *m_nextpkt;	/* Next packet in queue/record */
+	struct	mbuf *m_prevpkt;	/* Flags aren't used in the output queue */
+	int	m_flags;		/* Misc flags */
+
+	int	m_size;			/* Size of data */
+	struct	socket *m_so;
+
+	caddr_t	m_data;			/* Location of data */
+	int	m_len;			/* Amount of data in this mbuf */
+
 	Slirp *slirp;
 	bool	arp_requested;
 	uint64_t expiration_date;
 	/* start of dynamic buffer area, must be last element */
-	union M_dat {
-		char	m_dat_[1]; /* ANSI don't like 0 sized arrays */
-		char	*m_ext_;
-	} M_dat;
+	union {
+		char	m_dat[1]; /* ANSI don't like 0 sized arrays */
+		char	*m_ext;
+	};
 };
 
-#define m_next		m_hdr.mh_next
-#define m_prev		m_hdr.mh_prev
-#define m_nextpkt	m_hdr.mh_nextpkt
-#define m_prevpkt	m_hdr.mh_prevpkt
-#define m_flags		m_hdr.mh_flags
-#define	m_len		m_hdr.mh_len
-#define	m_data		m_hdr.mh_data
-#define m_size		m_hdr.mh_size
-#define m_dat		M_dat.m_dat_
-#define m_ext		M_dat.m_ext_
-#define m_so		m_hdr.mh_so
-
 #define ifq_prev m_prev
 #define ifq_next m_next
 #define ifs_prev m_prevpkt
diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
index e98ce1a..043f28f 100644
--- a/slirp/tcp_subr.c
+++ b/slirp/tcp_subr.c
@@ -647,7 +647,7 @@ tcp_emu(struct socket *so, struct mbuf *m)
 			n4 =  (laddr & 0xff);
 
 			m->m_len = bptr - m->m_data; /* Adjust length */
-                        m->m_len += snprintf(bptr, m->m_hdr.mh_size - m->m_len,
+                        m->m_len += snprintf(bptr, m->m_size - m->m_len,
                                              "ORT %d,%d,%d,%d,%d,%d\r\n%s",
                                              n1, n2, n3, n4, n5, n6, x==7?buff:"");
 			return 1;
@@ -680,7 +680,7 @@ tcp_emu(struct socket *so, struct mbuf *m)
 			n4 =  (laddr & 0xff);
 
 			m->m_len = bptr - m->m_data; /* Adjust length */
-			m->m_len += snprintf(bptr, m->m_hdr.mh_size - m->m_len,
+			m->m_len += snprintf(bptr, m->m_size - m->m_len,
                                              "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
                                              n1, n2, n3, n4, n5, n6, x==7?buff:"");
 
@@ -706,7 +706,7 @@ tcp_emu(struct socket *so, struct mbuf *m)
 		if (m->m_data[m->m_len-1] == '\0' && lport != 0 &&
 		    (so = tcp_listen(slirp, INADDR_ANY, 0, so->so_laddr.s_addr,
 		                     htons(lport), SS_FACCEPTONCE)) != NULL)
-                    m->m_len = snprintf(m->m_data, m->m_hdr.mh_size, "%d",
+                    m->m_len = snprintf(m->m_data, m->m_size, "%d",
                                         ntohs(so->so_fport)) + 1;
 		return 1;
 
@@ -726,7 +726,7 @@ tcp_emu(struct socket *so, struct mbuf *m)
 				return 1;
 			}
 			m->m_len = bptr - m->m_data; /* Adjust length */
-                        m->m_len += snprintf(bptr, m->m_hdr.mh_size,
+                        m->m_len += snprintf(bptr, m->m_size,
                                              "DCC CHAT chat %lu %u%c\n",
                                              (unsigned long)ntohl(so->so_faddr.s_addr),
                                              ntohs(so->so_fport), 1);
@@ -737,7 +737,7 @@ tcp_emu(struct socket *so, struct mbuf *m)
 				return 1;
 			}
 			m->m_len = bptr - m->m_data; /* Adjust length */
-                        m->m_len += snprintf(bptr, m->m_hdr.mh_size,
+                        m->m_len += snprintf(bptr, m->m_size,
                                              "DCC SEND %s %lu %u %u%c\n", buff,
                                              (unsigned long)ntohl(so->so_faddr.s_addr),
                                              ntohs(so->so_fport), n1, 1);
@@ -748,7 +748,7 @@ tcp_emu(struct socket *so, struct mbuf *m)
 				return 1;
 			}
 			m->m_len = bptr - m->m_data; /* Adjust length */
-                        m->m_len += snprintf(bptr, m->m_hdr.mh_size,
+                        m->m_len += snprintf(bptr, m->m_size,
                                              "DCC MOVE %s %lu %u %u%c\n", buff,
                                              (unsigned long)ntohl(so->so_faddr.s_addr),
                                              ntohs(so->so_fport), n1, 1);
-- 
1.7.10.4

Re: [Qemu-devel] [Qemu-trivial] [PATCH] slirp: reorder include to fix FreeBSD build failure

[Ed Maste]

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On 13 July 2013 05:12, Michael Tokarev <mjt@tls.msk.ru> wrote:

> Remaining:
>
> struct mbuf {
>         union M_dat {
>                 char    m_dat_[1]; /* ANSI don't like 0 sized arrays */
>                 char    *m_ext_;
>         } M_dat;
> };
>
> #define m_dat           M_dat.m_dat_
> #define m_ext           M_dat.m_ext_
>
> This can be done by using an unnamed union, ie, by omitting
>

Yeah, struct mbuf and those #defines date back to the beginning of BSD
networking.

I think we're probably unconcerned with a slirp upstream at this point, so
such a change seems reasonable.  I'm not sure that anonymous union support
is universal across all compilers used to build QEMU though - do you know?

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Re: [Qemu-devel] [Qemu-trivial] [PATCH] slirp: reorder include to fix FreeBSD build failure

[Peter Maydell]

On 13 July 2013 23:35, Ed Maste <emaste@freebsd.org> wrote:
> I'm not sure that anonymous union support is universal across
> all compilers used to build QEMU though - do you know?

A quick grep shows we already use anonymous unions in
a few places, so it must be OK.

-- PMM

Re: [Qemu-devel] [Qemu-trivial] [PATCH] slirp: reorder include to fix FreeBSD build failure

[Jan Kiszka]

On 2013-07-14 00:35, Ed Maste wrote:
> On 13 July 2013 05:12, Michael Tokarev <mjt@tls.msk.ru<mailto:mjt@tls.msk.ru>> wrote:
> Remaining:
> 
> struct mbuf {
>         union M_dat {
>                 char    m_dat_[1]; /* ANSI don't like 0 sized arrays */
>                 char    *m_ext_;
>         } M_dat;
> };
> 
> #define m_dat           M_dat.m_dat_
> #define m_ext           M_dat.m_ext_
> 
> This can be done by using an unnamed union, ie, by omitting
> 
> Yeah, struct mbuf and those #defines date back to the beginning of BSD networking.
> 
> I think we're probably unconcerned with a slirp upstream at this point, so such a change seems reasonable. 

Indeed, they are always welcome. There is no point in tracking upstream
anymore.

> I'm not sure that anonymous union support is universal across all compilers used to build QEMU though - do you know?

No problem, as Peter already said. Please provide an according patch.

Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux

Re: [Qemu-devel] [Qemu-trivial] [PATCH] slirp: reorder include to fix FreeBSD build failure

[Michael Tokarev]

17.07.2013 12:32, Jan Kiszka wrote:
> No problem, as Peter already said. Please provide an according patch.

http://thread.gmane.org/gmane.comp.emulators.qemu/221949/focus=221975
 (an attachtment there)
http://git.corpit.ru/?p=qemu.git;a=commitdiff;h=2915c3b20260b1a653fced3b584d0c2b012880dc

Thanks,

/mjt

Re: [Qemu-devel] [Qemu-trivial] [PATCH] slirp: reorder include to fix FreeBSD build failure

[Ed Maste]

On 17 July 2013 04:54, Michael Tokarev <mjt@tls.msk.ru> wrote:
> 17.07.2013 12:32, Jan Kiszka wrote:
>> No problem, as Peter already said. Please provide an according patch.
>
> http://thread.gmane.org/gmane.comp.emulators.qemu/221949/focus=221975
>  (an attachtment there)
> http://git.corpit.ru/?p=qemu.git;a=commitdiff;h=2915c3b20260b1a653fced3b584d0c2b012880dc

I'm happy with Michael's patch.