[new PATCH] Re: 8139too: defunct threads

Manfred Spraul
2001-04-15T13:08:00Z

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I found the problem:

* init uses waitpid(-1,,), thus the __WALL flag is not set
* without __WALL, only processes with exit_signal == SIGCHLD are reaped
* it's impossible for user space processes to die with another
exit_signal, forget_original_parent changes the exit_signal back to
SIGCHLD ("We dont want people slaying init"), and init itself doesn't
use clone.
* kernel threads can die with an arbitrary exit_signal.

Alan, which fix would you prefer:
* init could use wait3 and set __WALL.
* all kernel thread users could set SIGCHLD. Some already do that
(__call_usermodehelper).
* the kernel_thread implementations could force the exit signal to
SIGCHLD.

I'd prefer the last version.
The attached patch is tested with i386. The alpha, parisc and ppc
assember changes are guessed.

--
Manfred

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diff -ur 2.4/arch/alpha/kernel/entry.S build-2.4/arch/alpha/kernel/entry.S
--- 2.4/arch/alpha/kernel/entry.S Sun Sep 3 20:36:45 2000
+++ build-2.4/arch/alpha/kernel/entry.S Sun Apr 15 14:58:01 2001
@@ -242,12 +242,12 @@
subq $30,4*8,$30
stq $10,16($30)
stq $9,8($30)
- lda $0,CLONE_VM
+ lda $0,CLONE_VM|SIGCHLD
stq $26,0($30)
.prologue 1
mov $16,$9 /* save fn */
mov $17,$10 /* save arg */
- or $18,$0,$16 /* shuffle flags to front; add CLONE_VM. */
+ or $18,$0,$16 /* shuffle flags to front; add CLONE_VM|SIGCHLD. */
bsr $26,kernel_clone
bne $20,1f /* $20 is non-zero in child */
ldq $26,0($30)
diff -ur 2.4/arch/arm/kernel/process.c build-2.4/arch/arm/kernel/process.c
--- 2.4/arch/arm/kernel/process.c Thu Feb 22 22:28:51 2001
+++ build-2.4/arch/arm/kernel/process.c Sun Apr 15 14:51:08 2001
@@ -368,6 +368,8 @@
{
pid_t __ret;

+ flags |= SIGCHLD;
+
__asm__ __volatile__(
"orr r0, %1, %2 @ kernel_thread sys_clone
mov r1, #0
diff -ur 2.4/arch/cris/kernel/process.c build-2.4/arch/cris/kernel/process.c
--- 2.4/arch/cris/kernel/process.c Sat Apr 7 22:01:49 2001
+++ build-2.4/arch/cris/kernel/process.c Sun Apr 15 14:51:16 2001
@@ -127,6 +127,8 @@
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
register long __a __asm__ ("r10");
+
+ flags |= SIGCHLD;

__asm__ __volatile__
("movu.w %1,r9\n\t" /* r9 contains syscall number, to sys_clone */
diff -ur 2.4/arch/i386/kernel/process.c build-2.4/arch/i386/kernel/process.c
--- 2.4/arch/i386/kernel/process.c Thu Feb 22 22:28:52 2001
+++ build-2.4/arch/i386/kernel/process.c Sun Apr 15 14:40:43 2001
@@ -440,6 +440,8 @@
{
long retval, d0;

+ flags |= SIGCHLD;
+
__asm__ __volatile__(
"movl %%esp,%%esi\n\t"
"int $0x80\n\t" /* Linux/i386 system call */
diff -ur 2.4/arch/ia64/kernel/process.c build-2.4/arch/ia64/kernel/process.c
--- 2.4/arch/ia64/kernel/process.c Thu Jan 4 21:50:17 2001
+++ build-2.4/arch/ia64/kernel/process.c Sun Apr 15 14:51:44 2001
@@ -500,7 +500,7 @@
struct task_struct *parent = current;
int result, tid;

- tid = clone(flags | CLONE_VM, 0);
+ tid = clone(flags | CLONE_VM | SIGCHLD, 0);
if (parent != current) {
result = (*fn)(arg);
_exit(result);
diff -ur 2.4/arch/m68k/kernel/process.c build-2.4/arch/m68k/kernel/process.c
--- 2.4/arch/m68k/kernel/process.c Thu Feb 22 22:28:54 2001
+++ build-2.4/arch/m68k/kernel/process.c Sun Apr 15 14:51:58 2001
@@ -135,7 +135,7 @@

{
register long retval __asm__ ("d0");
- register long clone_arg __asm__ ("d1") = flags | CLONE_VM;
+ register long clone_arg __asm__ ("d1") = flags | CLONE_VM | SIGCHLD;

__asm__ __volatile__
("clrl %%d2\n\t"
diff -ur 2.4/arch/mips/kernel/process.c build-2.4/arch/mips/kernel/process.c
--- 2.4/arch/mips/kernel/process.c Sat Apr 7 22:01:56 2001
+++ build-2.4/arch/mips/kernel/process.c Sun Apr 15 14:52:12 2001
@@ -161,6 +161,8 @@
{
long retval;

+ flags |= SIGCHLD;
+
__asm__ __volatile__(
".set\tnoreorder\n\t"
"move\t$6,$sp\n\t"
diff -ur 2.4/arch/mips64/kernel/process.c build-2.4/arch/mips64/kernel/process.c
--- 2.4/arch/mips64/kernel/process.c Thu Feb 22 22:28:55 2001
+++ build-2.4/arch/mips64/kernel/process.c Sun Apr 15 14:52:21 2001
@@ -154,6 +154,8 @@
{
int retval;

+ flags |= SIGCHLD;
+
__asm__ __volatile__(
"move\t$6, $sp\n\t"
"move\t$4, %5\n\t"
diff -ur 2.4/arch/parisc/kernel/entry.S build-2.4/arch/parisc/kernel/entry.S
--- 2.4/arch/parisc/kernel/entry.S Sat Apr 7 22:01:58 2001
+++ build-2.4/arch/parisc/kernel/entry.S Sun Apr 15 14:56:58 2001
@@ -497,7 +497,7 @@
#endif
STREG %r26, PT_GR26(%r1) /* Store function & argument for child */
STREG %r25, PT_GR25(%r1)
- ldo CLONE_VM(%r0), %r26 /* Force CLONE_VM since only init_mm */
+ ldo SIGCHLD|CLONE_VM(%r0), %r26 /* Force CLONE_VM since only init_mm */
or %r26, %r24, %r26 /* will have kernel mappings. */
copy %r0, %r25
bl do_fork, %r2
diff -ur 2.4/arch/ppc/kernel/misc.S build-2.4/arch/ppc/kernel/misc.S
--- 2.4/arch/ppc/kernel/misc.S Sat Apr 7 22:01:59 2001
+++ build-2.4/arch/ppc/kernel/misc.S Sun Apr 15 14:56:17 2001
@@ -1080,7 +1080,7 @@
*/
_GLOBAL(kernel_thread)
mr r6,r3 /* function */
- ori r3,r5,CLONE_VM /* flags */
+ ori r3,r5,CLONE_VM|SIGCHLD /* flags */
li r0,__NR_clone
sc
cmpi 0,r3,0 /* parent or child? */
diff -ur 2.4/arch/s390/kernel/process.c build-2.4/arch/s390/kernel/process.c
--- 2.4/arch/s390/kernel/process.c Thu Feb 22 22:28:57 2001
+++ build-2.4/arch/s390/kernel/process.c Sun Apr 15 14:52:58 2001
@@ -242,7 +242,7 @@

int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
- int clone_arg = flags | CLONE_VM;
+ int clone_arg = flags | CLONE_VM | SIGCHLD;
int retval;

__asm__ __volatile__(
diff -ur 2.4/arch/s390x/kernel/process.c build-2.4/arch/s390x/kernel/process.c
--- 2.4/arch/s390x/kernel/process.c Thu Feb 22 22:28:57 2001
+++ build-2.4/arch/s390x/kernel/process.c Sun Apr 15 14:53:06 2001
@@ -242,7 +242,7 @@

int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
- int clone_arg = flags | CLONE_VM;
+ int clone_arg = flags | CLONE_VM | SIGCHLD;
int retval;

__asm__ __volatile__(
diff -ur 2.4/arch/sh/kernel/process.c build-2.4/arch/sh/kernel/process.c
--- 2.4/arch/sh/kernel/process.c Thu Feb 22 22:28:57 2001
+++ build-2.4/arch/sh/kernel/process.c Sun Apr 15 14:53:16 2001
@@ -148,7 +148,7 @@
{ /* Don't use this in BL=1(cli). Or else, CPU resets! */
register unsigned long __sc0 __asm__ ("r0");
register unsigned long __sc3 __asm__ ("r3") = __NR_clone;
- register unsigned long __sc4 __asm__ ("r4") = (long) flags | CLONE_VM;
+ register unsigned long __sc4 __asm__ ("r4") = (long) flags | CLONE_VM | SIGCHLD;
register unsigned long __sc5 __asm__ ("r5") = 0;
register unsigned long __sc8 __asm__ ("r8") = (long) arg;
register unsigned long __sc9 __asm__ ("r9") = (long) fn;
diff -ur 2.4/arch/sparc/kernel/process.c build-2.4/arch/sparc/kernel/process.c
--- 2.4/arch/sparc/kernel/process.c Thu Feb 22 22:28:57 2001
+++ build-2.4/arch/sparc/kernel/process.c Sun Apr 15 14:53:39 2001
@@ -678,6 +678,8 @@
{
long retval;

+ flags |= SIGCHLD;
+
__asm__ __volatile("mov %4, %%g2\n\t" /* Set aside fn ptr... */
"mov %5, %%g3\n\t" /* and arg. */
"mov %1, %%g1\n\t"
diff -ur 2.4/arch/sparc64/kernel/process.c build-2.4/arch/sparc64/kernel/process.c
--- 2.4/arch/sparc64/kernel/process.c Sat Mar 31 21:47:37 2001
+++ build-2.4/arch/sparc64/kernel/process.c Sun Apr 15 14:53:49 2001
@@ -647,6 +647,8 @@
{
long retval;

+ flags |= SIGCHLD;
+
/* If the parent runs before fn(arg) is called by the child,
* the input registers of this function can be clobbered.
* So we stash 'fn' and 'arg' into global registers which