Date: Wed, 16 Jun 1999 17:49:12 +0200 (CEST) From: dirk.meyer@dinoex.sub.org To: FreeBSD-gnats-submit@freebsd.org Subject: kern/12247: userlevel program let kernel hang Message-ID: <199906161549.RAA00552@home.dinoex.sub.org>
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>Number: 12247
>Category: kern
>Synopsis: userlevel program let kernel hang
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Jun 16 09:20:01 PDT 1999
>Closed-Date:
>Last-Modified:
>Originator: Dirk Meyer
>Release: FreeBSD 3.2-RELEASE i386
>Organization:
privat
>Environment:
FreeBSD 3.2-RELEASE i386
FreeBSD 2.2.8-RELEASE i386
KERNEL.GENERIC and my custom KERNELS
/usr/bin/gdb
>Description:
while debugging a userlevel program
The user can hang the system,
no other processes seem to work.
>How-To-Repeat:
(sync all data first)
extract this shar file,
create the executable with "gmake"
and run the script "hangme.sh"
Send a signal <CTRL>+<C> to the debugger
# This is a shell archive. Save it in a file, remove anything before
# this line, and then unpack it by entering "sh file". Note, it may
# create directories; files and directories will be owned by you and
# have default permissions.
#
# This archive contains:
#
# hangme
# hangme/hangme.c
# hangme/hangme.sh
# hangme/GNUmakefile
#
echo c - hangme
mkdir -p hangme > /dev/null 2>&1
echo x - hangme/hangme.c
sed 's/^X//' >hangme/hangme.c << 'END-of-hangme/hangme.c'
X/******************************************************************
X* HANGME.C
X******************************************************************/
X
X/******************************************************************
X*
X* This Programm should test a problem with locking
X*
X* Copyright (c) 1992,1993,1994,1995,1996,1997,1998,1999
X* by Dirk Meyer, All rights reserved.
X* Im Grund 4, 34317 Habichtswald, Germany
X* Email: dirk.meyer@dinoex.sub.org
X*
X******************************************************************/
X
X#include <stdio.h>
X#include <stdlib.h>
X#include <string.h>
X
X#include <unistd.h>
X#include <fcntl.h>
X#include <signal.h>
X#include <errno.h>
X
X/******************************************************************
X******************************************************************/
X
Xtypedef int lockhandle_t;
X
Xconst char *const *Argv;
X
Xpid_t Session_gpid;
X
Xconst char *Logfile = "logfile";
X
Xvolatile int Hang_up;
X
X/******************************************************************
X******************************************************************/
X
Xvoid lock_handle( lockhandle_t handle, const char *datei )
X{
X int st;
X
X if ( datei == NULL )
X return;
X
X /* CONSTANTCONDITION */
X while ( 1 ) {
X st = flock( handle, LOCK_EX | LOCK_NB );
X if ( st == 0 )
X break;
X if ( errno == EWOULDBLOCK ) {
X printf( "blocked by <%s>\n", datei );
X break;
X };
X fprintf( stderr,
X "lock <%s> returns %d: %s", datei, st,
X strerror( errno ) );
X if ( errno == ENOLCK ) {
X sleep( 20 );
X continue;
X };
X return;
X };
X /* CONSTANTCONDITION */
X while ( 1 ) {
X st = flock( handle, LOCK_EX );
X if ( st == 0 )
X break;
X fprintf( stderr,
X "lock <%s> returns %d: %s", datei, st,
X strerror( errno ) );
X if ( errno == ENOLCK ) {
X sleep( 20 );
X continue;
X };
X return;
X }
X}
X
X/******************************************************************
X******************************************************************/
X
XFILE *file_open( const char *datei, const char *mode )
X{
X FILE *handle;
X
X if ( datei == NULL )
X return ( NULL );
X
X handle = fopen( datei, mode );
X if ( handle == NULL )
X fprintf( stderr,
X "Fatal: Datei '%s' nicht verfuegbar", datei );
X if ( mode[ 0 ] != 'r' )
X lock_handle( fileno( handle ), datei );
X return ( handle );
X}
X
Xvoid file_close( FILE *handle )
X{
X int status;
X
X status = fclose( handle );
X if ( status != 0 ) {
X fprintf( stderr,
X "Fatal: Fehler %d beim Schliessen der Datei",
X status );
X }
X}
X
X/******************************************************************
X******************************************************************/
X
X#ifdef __FreeBSD__
X#undef SIG_DFL
X#define SIG_DFL (void (*)(int))0
X#undef SIG_IGN
X#define SIG_IGN (void (*)(int))1
X#endif
X
Xvoid my_appl_exit( void );
Xvoid my_appl_exit( void )
X{
X signal( SIGHUP, SIG_DFL );
X signal( SIGQUIT, SIG_DFL );
X}
X
Xvoid onquit( int test );
X/* ARGSUSED */
Xvoid onquit( int test )
X{
X fprintf( stderr, "QUIT-Signal\n" );
X signal( SIGQUIT, onquit );
X
X signal( SIGHUP, SIG_IGN );
X signal( SIGTERM, SIG_IGN );
X if ( Session_gpid > 1 )
X (void)kill( -Session_gpid, SIGHUP );
X if ( Session_gpid > 1 )
X (void)kill( -Session_gpid, SIGTERM );
X my_appl_exit();
X execv( Argv[ 0 ], (char *const *)Argv );
X}
X
Xvoid onhangup( int test );
X/* ARGSUSED */
Xvoid onhangup( int test )
X{
X FILE *flog;
X
X fprintf( stderr, "HANGUP-Signal\n" );
X if ( Hang_up == 0 ) {
X signal( SIGHUP, SIG_IGN );
X if ( Session_gpid > 1 ) {
X (void)kill( -Session_gpid, SIGHUP );
X }
X };
X Hang_up = 1;
X signal( SIGHUP, onhangup );
X
X /* deadlock */
X flog = file_open( Logfile, "ab" );
X file_close( flog );
X}
X
Xvoid my_appl_init( void );
Xvoid my_appl_init( void )
X{
X#ifdef __FreeBSD__
X int error;
X#endif
X
X atexit( my_appl_exit );
X#ifdef __FreeBSD__
X error = setpgid( 0, getppid() );
X if ( error < 0 ) {
X fprintf( stderr,
X "!!! Fehler %d in "
X "'setpgid( ppid=%ld )' :%s",
X error, (long)getppid(),
X strerror( errno ) );
X };
X Session_gpid = setsid();
X if ( Session_gpid < (pid_t)0 ) {
X fprintf( stderr,
X "!!! Fehler %d in "
X "'setsid()' :%s", error,
X strerror( errno ) );
X };
X#else
X Session_gpid = 0;
X#endif
X signal( SIGHUP, onhangup );
X signal( SIGQUIT, onquit );
X}
X
Xvoid main( int argc, const char *const *argv );
Xvoid main( int argc, const char *const *argv )
X{
X FILE *flog;
X
X Hang_up = 0;
X Argv = argv;
X my_appl_init();
X flog = file_open( Logfile, "ab" );
X fputs( "main\n", flog );
X while ( Hang_up == 0 )
X ;
X file_close( flog );
X exit( 0 );
X}
X
X/******************************************************************
X* END OF FILE HANGUP.C
X******************************************************************/
END-of-hangme/hangme.c
echo x - hangme/hangme.sh
sed 's/^X//' >hangme/hangme.sh << 'END-of-hangme/hangme.sh'
X#!/bin/sh
X#
X# (c) 1994-99, Dirk Meyer, Im Grund 4, 34317 Habichtswald
X#
Xnpid="$$"
X./hangme &
Xsleep 1
Xnpid=`expr ${npid} + 1`
Xecho "${npid}"
Xkillall -1 hangme
Xsleep 1
Xgdb ./hangme "${npid}" << 'EOF'
Xq
XEOF
Xgdb ./hangme "${npid}" << 'EOF'
Xq
XEOF
Xkillall -9 hangme
X#
X# eof
END-of-hangme/hangme.sh
echo x - hangme/GNUmakefile
sed 's/^X//' >hangme/GNUmakefile << 'END-of-hangme/GNUmakefile'
X
XCPPFLAGS+= -Wall
XCFLAGS+= -g
XLDLAGS+= -g
X
Xall: hangme
X
END-of-hangme/GNUmakefile
exit
>Fix:
none found
>Release-Note:
>Audit-Trail:
>Unformatted:
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