On Thu, Mar 17, 2022 at 02:09:39PM +0100, Mark Kettenis wrote:
> I fear the fundamental problem is that we should not expose data
> structures internal to the kernel to userland. What I don't
> understand though is how that happens. The sysctl code doesn't seem
> to export "struct inpcb" instances directly, but instead it exports
> selected members through "struct kinfo_file". So why is "struct
> inpcb" exposed to userland at all?
A few tools use it. One thing is post mortem analysis of kernel
core dumps. Sometimes I get dumps sent from customers. They don't
have WITNESS.
Some traditional network debugging tools use these strutures.
lib/libkvm
sbin/sysctl
usr.bin/netstat
usr.bin/tcpbench
usr.sbin/trpt
As you need sysctl kern.allowkmem=1 for them this is only useful
on debugging machines. Ob course they can be rewritten using sysctl.
A drawback is that you have to write a lot of copy code and post
mortem analysis code gets out of sync. I see tools with -M -N
breaking over time.
The question is how to proceed. For MP in the network stack I need
mutex in structs. And I don't want to rewrite all tools before
making progress.
bluhm
> > Index: sys/netinet/in_pcb.h
> > ===================================================================
> > RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/in_pcb.h,v
> > retrieving revision 1.125
> > diff -u -p -r1.125 in_pcb.h
> > --- sys/netinet/in_pcb.h 14 Mar 2022 22:38:43 -0000 1.125
> > +++ sys/netinet/in_pcb.h 17 Mar 2022 00:44:54 -0000
> > @@ -65,6 +65,7 @@
> > #define _NETINET_IN_PCB_H_
> >
> > #include <sys/queue.h>
> > +#include <sys/mutex.h>
> > #include <sys/refcnt.h>
> > #include <netinet/ip6.h>
> > #include <netinet6/ip6_var.h>
> > Index: sys/sys/mutex.h
> > ===================================================================
> > RCS file: /data/mirror/openbsd/cvs/src/sys/sys/mutex.h,v
> > retrieving revision 1.18
> > diff -u -p -r1.18 mutex.h
> > --- sys/sys/mutex.h 23 Apr 2019 13:35:12 -0000 1.18
> > +++ sys/sys/mutex.h 17 Mar 2022 00:44:23 -0000
> > @@ -48,6 +48,8 @@ struct mutex {
> > #endif
> > };
> >
> > +#ifdef _KERNEL
> > +
> > /*
> > * To prevent lock ordering problems with the kernel lock, we need to
> > * make sure we block all interrupts that can grab the kernel lock.
> > @@ -148,7 +150,7 @@ void _mtx_init_flags(struct mutex *, int
> >
> > #endif /* WITNESS */
> >
> > -#if defined(_KERNEL) && defined(DDB)
> > +#ifdef DDB
> >
> > struct db_mutex {
> > struct cpu_info *mtx_owner;
> > @@ -160,6 +162,8 @@ struct db_mutex {
> > void db_mtx_enter(struct db_mutex *);
> > void db_mtx_leave(struct db_mutex *);
> >
> > -#endif /* _KERNEL && DDB */
> > +#endif /* DDB */
> > +
> > +#endif /* _KERNEL */
> >
> > #endif
> >
> >
