[PATCH] Third version of signal changes for thread groups

During the course of developing our pthread library (the NGPT pthread
library) it became clear we needed some kernel support for handling
signals.  This patch helps the library by redirecting all signals sent
to tasks in a thread group to the thread group leader.  It also defines
the tkill() system call so the library can signal a specific task if
necessary. 

Given that as far as I know NGPT is the only user of thread groups, and
that this change would benefit any other user of thread groups, I'm
submitting this for inclusion in the 2.5 kernel.

Note that this patch also adds support for sys_gettid() for the
architectures that don't have it.  While this could have been split into a
spearate patch, it would create conflicts since this patch also adds
sys_tkill(), so I felt it was cleaner to leave them together.

Dave McCracken

======================================================================
Dave McCracken          IBM Linux Base Kernel Team      1-512-838-3059
dmccr@us.ibm.com                                        T/L   678-3059

arch/alpha/kernel/entry.S

@@ -1148,3 +1148,4 @@ sys_call_table:
 	.quad sys_gettid
 	.quad sys_readahead
 	.quad sys_ni_syscall			/* 380, sys_security */
+	.quad sys_tkill

arch/alpha/kernel/signal.c

@@ -717,9 +717,7 @@ do_signal(sigset_t *oldset, struct pt_regs * regs, struct switch_stack * sw,
 
 			default:
 				lock_kernel();
-				sigaddset(&current->pending.signal, signr);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 			continue;

arch/arm/kernel/calls.S

@@ -236,6 +236,8 @@ __syscall_start:
 		.long	SYMBOL_NAME(sys_mincore)
 /* 220 */	.long	SYMBOL_NAME(sys_madvise)
 		.long	SYMBOL_NAME(sys_fcntl64)
+		.long	SYMBOL_NAME(sys_gettid)
+		.long	SYMBOL_NAME(sys_tkill)
 __syscall_end:
 
 		.rept	NR_syscalls - (__syscall_end - __syscall_start) / 4

arch/arm/kernel/signal.c

@@ -637,10 +637,7 @@ asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
 				/* FALLTHRU */
 
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/cris/kernel/entry.S

@@ -1015,6 +1015,7 @@ sys_call_table:
         .long SYMBOL_NAME(sys_ni_syscall)       /* Reserved for Security */
         .long SYMBOL_NAME(sys_gettid)
         .long SYMBOL_NAME(sys_readahead)        /* 225 */
+        .long SYMBOL_NAME(sys_tkill)
 
         /*
          * NOTE!! This doesn't have to be exact - we just have

arch/cris/kernel/signal.c

@@ -679,10 +679,7 @@ int do_signal(int canrestart, sigset_t *oldset, struct pt_regs *regs)
 
 			default:
 				lock_kernel();
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/i386/kernel/entry.S

@@ -667,6 +667,7 @@ ENTRY(sys_call_table)
 	.long SYMBOL_NAME(sys_removexattr)	/* 235 */
 	.long SYMBOL_NAME(sys_lremovexattr)
 	.long SYMBOL_NAME(sys_fremovexattr)
+ 	.long SYMBOL_NAME(sys_tkill)
 
 	.rept NR_syscalls-(.-sys_call_table)/4
 		.long SYMBOL_NAME(sys_ni_syscall)

arch/i386/kernel/signal.c

@@ -683,10 +683,7 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 				/* FALLTHRU */
 
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/ia64/kernel/entry.S

@@ -1130,6 +1130,7 @@ sys_call_table:
 	data8 sys_getdents64
 	data8 sys_getunwind			// 1215
 	data8 sys_readahead
+	data8 sys_tkill
 	data8 ia64_ni_syscall
 	data8 ia64_ni_syscall
 	data8 ia64_ni_syscall

arch/ia64/kernel/signal.c

@@ -578,10 +578,7 @@ ia64_do_signal (sigset_t *oldset, struct sigscratch *scr, long in_syscall)
 				/* FALLTHRU */
 
 			      default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/m68k/kernel/entry.S

@@ -646,6 +646,8 @@ SYMBOL_NAME_LABEL(sys_call_table)
 	.long SYMBOL_NAME(sys_ni_syscall)
 	.long SYMBOL_NAME(sys_ni_syscall)
 	.long SYMBOL_NAME(sys_getdents64)	/* 220 */
+	.long SYMBOL_NAME(sys_gettid)
+	.long SYMBOL_NAME(sys_tkill)
 
 	.rept NR_syscalls-(.-SYMBOL_NAME(sys_call_table))/4
 		.long SYMBOL_NAME(sys_ni_syscall)

arch/m68k/kernel/signal.c

@@ -1135,10 +1135,7 @@ asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs)
 				/* FALLTHRU */
 
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/mips/kernel/signal.c

@@ -661,10 +661,7 @@ asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs)
 				/* FALLTHRU */
 
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/mips/kernel/syscalls.h

@@ -235,3 +235,5 @@ SYS(sys_mincore, 3)
 SYS(sys_madvise, 3)
 SYS(sys_getdents64, 3)
 SYS(sys_fcntl64, 3)				/* 4220 */
+SYS(sys_gettid, 0)
+SYS(sys_tkill, 2)

arch/mips64/kernel/scall_64.S

@@ -347,3 +347,5 @@ sys_call_table:
 	PTR	sys_mincore
 	PTR	sys_madvise
 	PTR	sys_getdents64
+	PTR	sys_gettid
+	PTR	sys_tkill

arch/mips64/kernel/scall_o32.S

@@ -454,6 +454,8 @@ illegal_syscall:
 	sys	sys_madvise	3
 	sys	sys_getdents64	3
 	sys	sys32_fcntl64	3			/* 4220 */
+	sys	sys32_gettid	0
+	sys	sys32_tkill	2
 	.endm
 
 	.macro	sys function, nargs

arch/mips64/kernel/signal.c

@@ -685,10 +685,7 @@ asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs)
 				/* FALLTHRU */
 
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/mips64/kernel/signal32.c

@@ -757,10 +757,7 @@ asmlinkage int do_signal32(sigset_t *oldset, struct pt_regs *regs)
 				/* FALLTHRU */
 
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/parisc/kernel/signal.c

@@ -581,11 +581,7 @@ do_signal(sigset_t *oldset, struct pt_regs *regs, int in_syscall)
 				/* FALLTHRU */
 
 			default:
-				lock_kernel();
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/parisc/kernel/syscall.S

@@ -552,6 +552,8 @@ sys_call_table:
 	ENTRY_UHOH(shmctl)		/* 195 */
 	ENTRY_SAME(ni_syscall)		/* streams1 */
 	ENTRY_SAME(ni_syscall)		/* streams2 */
+	ENTRY_SAME(gettid)
+	ENTRY_SAME(tkill)
 
 .end
 

arch/ppc/kernel/misc.S

@@ -1121,6 +1121,7 @@ _GLOBAL(sys_call_table)
 	.long sys_madvise	/* 205 */
 	.long sys_mincore
 	.long sys_gettid
+	.long sys_tkill
 	.rept NR_syscalls-(.-sys_call_table)/4
 		.long sys_ni_syscall
 	.endr

arch/ppc/kernel/signal.c

@@ -641,10 +641,7 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
 				/* FALLTHRU */
 
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/s390/kernel/entry.S

@@ -602,6 +602,8 @@ sys_call_table:
 	.long  sys_ni_syscall		 /* 224 - reserved for posix_acl */
 	.rept  255-224
 	.long  sys_ni_syscall
+	.long  sys_gettid		/* 226 */
+	.long  sys_tkill		/* 227 */
 	.endr
 
 /*

arch/s390/kernel/signal.c

@@ -563,10 +563,7 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
                                 /* FALLTHRU */
 
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/s390x/kernel/entry.S

@@ -635,6 +635,8 @@ sys_call_table:
 	.long  SYSCALL(sys_ni_syscall,sys_ni_syscall) /* 224 - reserved for posix_acl */
         .rept  255-224
 	.long  SYSCALL(sys_ni_syscall,sys_ni_syscall)
+	.long  SYSCALL(sys_gettid,sys_gettid)
+	.long  SYSCALL(sys_tkill,sys_tkill)
 	.endr
 
 /*

arch/s390x/kernel/signal.c

@@ -569,10 +569,7 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
                                 /* FALLTHRU */
 
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/s390x/kernel/signal32.c

@@ -699,10 +699,7 @@ int do_signal32(struct pt_regs *regs, sigset_t *oldset)
                                 /* FALLTHRU */
 
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/sh/kernel/entry.S

@@ -1195,6 +1195,8 @@ ENTRY(sys_call_table)
 	.long SYMBOL_NAME(sys_madvise)
 	.long SYMBOL_NAME(sys_getdents64)	/* 220 */
 	.long SYMBOL_NAME(sys_fcntl64)
+	.long SYMBOL_NAME(sys_gettid)
+	.long SYMBOL_NAME(sys_tkill)
 
 	/*
 	 * NOTE!! This doesn't have to be exact - we just have

arch/sh/kernel/signal.c

@@ -673,10 +673,7 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 				/* FALLTHRU */
 
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOTREACHED */
 			}
 		}

arch/sparc/kernel/signal.c

@@ -1280,10 +1280,7 @@ asmlinkage int do_signal(sigset_t *oldset, struct pt_regs * regs,
 #endif
 				/* fall through */
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOT REACHED */
 			}
 		}

arch/sparc/kernel/systbls.S

@@ -70,7 +70,7 @@ sys_call_table:
 /*240*/	.long sys_munlockall, sys_sched_setparam, sys_sched_getparam, sys_sched_setscheduler, sys_sched_getscheduler
 /*245*/	.long sys_sched_yield, sys_sched_get_priority_max, sys_sched_get_priority_min, sys_sched_rr_get_interval, sys_nanosleep
 /*250*/	.long sparc_mremap, sys_sysctl, sys_getsid, sys_fdatasync, sys_nfsservctl
-/*255*/	.long sys_nis_syscall, sys_nis_syscall
+/*255*/	.long sys_nis_syscall, sys_nis_syscall, sys_tkill
 
 #ifdef CONFIG_SUNOS_EMUL
 	/* Now the SunOS syscall table. */

arch/sparc64/kernel/signal.c

@@ -807,10 +807,7 @@ static int do_signal(sigset_t *oldset, struct pt_regs * regs,
 #endif
 				/* fall through */
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOT REACHED */
 			}
 		}

arch/sparc64/kernel/signal32.c

@@ -1479,10 +1479,7 @@ int do_signal32(sigset_t *oldset, struct pt_regs * regs,
 #endif
 				/* fall through */
 			default:
-				sigaddset(&current->pending.signal, signr);
-				recalc_sigpending(current);
-				current->flags |= PF_SIGNALED;
-				do_exit(exit_code);
+				sig_exit(signr, exit_code, &info);
 				/* NOT REACHED */
 			}
 		}

arch/sparc64/kernel/systbls.S

@@ -70,7 +70,7 @@ sys_call_table32:
 /*240*/	.word sys_munlockall, sys_sched_setparam, sys_sched_getparam, sys_sched_setscheduler, sys_sched_getscheduler
 	.word sys_sched_yield, sys_sched_get_priority_max, sys_sched_get_priority_min, sys32_sched_rr_get_interval, sys32_nanosleep
 /*250*/	.word sys32_mremap, sys32_sysctl, sys_getsid, sys_fdatasync, sys32_nfsservctl
-	.word sys_aplib
+	.word sys_aplib, sys_tkill
 
 	/* Now the 64-bit native Linux syscall table. */
 
@@ -129,7 +129,7 @@ sys_call_table:
 /*240*/	.word sys_munlockall, sys_sched_setparam, sys_sched_getparam, sys_sched_setscheduler, sys_sched_getscheduler
 	.word sys_sched_yield, sys_sched_get_priority_max, sys_sched_get_priority_min, sys_sched_rr_get_interval, sys_nanosleep
 /*250*/	.word sys64_mremap, sys_sysctl, sys_getsid, sys_fdatasync, sys_nfsservctl
-	.word sys_aplib
+	.word sys_aplib, sys_tkill
 
 #if defined(CONFIG_SUNOS_EMUL) || defined(CONFIG_SOLARIS_EMUL) || \
     defined(CONFIG_SOLARIS_EMUL_MODULE)

include/asm-alpha/siginfo.h

@@ -107,6 +107,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3		/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4		/* sent by AIO completion */
 #define SI_SIGIO	-5		/* sent by queued SIGIO */
+#define SI_TKILL	-6		/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-alpha/unistd.h

@@ -318,6 +318,7 @@
 #define __NR_gettid			378
 #define __NR_readahead			379
 #define __NR_security			380 /* syscall for security modules */
+#define __NR_tkill			381
 
 #if defined(__GNUC__)
 

include/asm-arm/siginfo.h

@@ -107,6 +107,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3		/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4		/* sent by AIO completion */
 #define SI_SIGIO	-5		/* sent by queued SIGIO */
+#define SI_TKILL        -6              /* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-cris/siginfo.h

@@ -107,6 +107,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3		/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4		/* sent by AIO completion */
 #define SI_SIGIO	-5		/* sent by queued SIGIO */
+#define SI_TKILL	-6		/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-cris/unistd.h

@@ -230,6 +230,7 @@
 #define __NR_security           223     /* syscall for security modules */
 #define __NR_gettid             224
 #define __NR_readahead          225
+#define __NR_tkill              226
 
 /* XXX - _foo needs to be __foo, while __NR_bar could be _NR_bar. */
 #define _syscall0(type,name) \

include/asm-i386/siginfo.h

@@ -107,6 +107,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3		/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4		/* sent by AIO completion */
 #define SI_SIGIO	-5		/* sent by queued SIGIO */
+#define SI_TKILL	-6		/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-i386/unistd.h

@@ -242,6 +242,7 @@
 #define __NR_removexattr	235
 #define __NR_lremovexattr	236
 #define __NR_fremovexattr	237
+#define __NR_tkill		238
 
 /* user-visible error numbers are in the range -1 - -124: see <asm-i386/errno.h> */
 

include/asm-ia64/siginfo.h

@@ -124,6 +124,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3		/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4		/* sent by AIO completion */
 #define SI_SIGIO	-5		/* sent by queued SIGIO */
+#define SI_TKILL	-6		/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-ia64/unistd.h

@@ -206,6 +206,7 @@
 #define __NR_getdents64			1214
 #define __NR_getunwind			1215
 #define __NR_readahead			1216
+#define __NR_tkill			1217
 
 #if !defined(__ASSEMBLY__) && !defined(ASSEMBLER)
 

include/asm-m68k/siginfo.h

@@ -117,6 +117,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3		/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4		/* sent by AIO completion */
 #define SI_SIGIO	-5		/* sent by queued SIGIO */
+#define SI_TKILL	-6		/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-m68k/unistd.h

@@ -222,6 +222,8 @@
 #define __NR_setfsuid32		215
 #define __NR_setfsgid32		216
 #define __NR_getdents64		220
+#define __NR_gettid		221
+#define __NR_tkill		222
 
 /* user-visible error numbers are in the range -1 - -122: see
    <asm-m68k/errno.h> */

include/asm-mips/siginfo.h

@@ -127,6 +127,7 @@ typedef struct siginfo {
 #define SI_TIMER __SI_CODE(__SI_TIMER,-3) /* sent by timer expiration */
 #define SI_MESGQ	-4	/* sent by real time mesq state change */
 #define SI_SIGIO	-5	/* sent by queued SIGIO */
+#define SI_TKILL	-6	/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-mips/unistd.h

@@ -233,6 +233,8 @@
 #define __NR_madvise			(__NR_Linux + 218)
 #define __NR_getdents64			(__NR_Linux + 219)
 #define __NR_fcntl64			(__NR_Linux + 220)
+#define __NR_gettid			(__NR_Linux + 221)
+#define __NR_tkill			(__NR_Linux + 222)
 
 /*
  * Offset of the last Linux flavoured syscall

include/asm-mips64/siginfo.h

@@ -127,6 +127,7 @@ typedef struct siginfo {
 #define SI_TIMER __SI_CODE(__SI_TIMER,-3) /* sent by timer expiration */
 #define SI_MESGQ	-4	/* sent by real time mesq state change */
 #define SI_SIGIO	-5	/* sent by queued SIGIO */
+#define SI_TKILL	-6	/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-mips64/unistd.h

@@ -461,11 +461,13 @@
 #define __NR_mincore			(__NR_Linux + 211)
 #define __NR_madvise			(__NR_Linux + 212)
 #define __NR_getdents64			(__NR_Linux + 213)
+#define __NR_gettid			(__NR_Linux + 214)
+#define __NR_tkill			(__NR_Linux + 215)
 
 /*
  * Offset of the last Linux flavoured syscall
  */
-#define __NR_Linux_syscalls		213
+#define __NR_Linux_syscalls		215
 
 #ifndef _LANGUAGE_ASSEMBLY
 

include/asm-parisc/siginfo.h

@@ -107,6 +107,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3		/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4		/* sent by AIO completion */
 #define SI_SIGIO	-5		/* sent by queued SIGIO */
+#define SI_TKILL	-6		/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-parisc/unistd.h

@@ -689,8 +689,10 @@
 
 #define __NR_getpmsg            (__NR_Linux + 196)      /* some people actually want streams */
 #define __NR_putpmsg            (__NR_Linux + 197)      /* some people actually want streams */
+#define __NR_gettid             (__NR_Linux + 198)
+#define __NR_tkill              (__NR_Linux + 199)
 
-#define __NR_Linux_syscalls     197
+#define __NR_Linux_syscalls     199
 
 #define HPUX_GATEWAY_ADDR       0xC0000004
 #define LINUX_GATEWAY_ADDR      0x100

include/asm-ppc/siginfo.h

@@ -108,6 +108,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3		/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4		/* sent by AIO completion */
 #define SI_SIGIO	-5		/* sent by queued SIGIO */
+#define SI_TKILL	-6		/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-ppc/unistd.h

@@ -215,6 +215,7 @@
 #define __NR_madvise		205
 #define __NR_mincore		206
 #define __NR_gettid		207
+#define __NR_tkill		208
 
 #define __NR(n)	#n
 

include/asm-s390/siginfo.h

@@ -115,6 +115,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3	/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4	/* sent by AIO completion */
 #define SI_SIGIO	-5	/* sent by queued SIGIO */
+#define SI_TKILL	-6	/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-s390/unistd.h

@@ -211,6 +211,8 @@
 #define __NR_mincore            218
 #define __NR_madvise            219
 #define __NR_getdents64		220
+#define __NR_gettid		226
+#define __NR_tkill		227
 
 
 /* user-visible error numbers are in the range -1 - -122: see <asm-s390/errno.h> */

include/asm-s390x/siginfo.h

@@ -115,6 +115,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3	/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4	/* sent by AIO completion */
 #define SI_SIGIO	-5	/* sent by queued SIGIO */
+#define SI_TKILL	-6	/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-s390x/unistd.h

@@ -181,6 +181,8 @@
 #define __NR_mincore            218
 #define __NR_madvise            219
 #define __NR_getdents64         220
+#define __NR_gettid		226
+#define __NR_tkill 	        227
 
 
 /* user-visible error numbers are in the range -1 - -122: see <asm-s390/errno.h> */

include/asm-sh/siginfo.h

@@ -107,6 +107,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3		/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4		/* sent by AIO completion */
 #define SI_SIGIO	-5		/* sent by queued SIGIO */
+#define SI_TKILL	-6		/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-sh/unistd.h

@@ -231,6 +231,8 @@
 #define __NR_madvise		219
 #define __NR_getdents64		220
 #define __NR_fcntl64		221
+#define __NR_gettid		222
+#define __NR_tkill		223
 
 /* user-visible error numbers are in the range -1 - -125: see <asm-sh/errno.h> */
 

include/asm-sparc/siginfo.h

@@ -112,6 +112,7 @@ typedef struct siginfo {
 #define SI_MESGQ	-3		/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4		/* sent by AIO completion */
 #define SI_SIGIO	-5		/* sent by queued SIGIO */
+#define SI_TKILL	-6		/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-sparc/unistd.h

@@ -271,6 +271,7 @@
 #define __NR_fdatasync          253
 #define __NR_nfsservctl         254
 #define __NR_aplib              255
+#define __NR_tkill              257
 
 #define _syscall0(type,name) \
 type name(void) \

include/asm-sparc64/siginfo.h

@@ -172,6 +172,7 @@ typedef struct siginfo32 {
 #define SI_MESGQ	-3		/* sent by real time mesq state change */
 #define SI_ASYNCIO	-4		/* sent by AIO completion */
 #define SI_SIGIO	-5		/* sent by queued SIGIO */
+#define SI_TKILL	-6		/* sent by tkill system call */
 
 #define SI_FROMUSER(siptr)	((siptr)->si_code <= 0)
 #define SI_FROMKERNEL(siptr)	((siptr)->si_code > 0)

include/asm-sparc64/unistd.h

@@ -273,6 +273,7 @@
 #define __NR_fdatasync          253
 #define __NR_nfsservctl         254
 #define __NR_aplib              255
+#define __NR_tkill              256
 
 #define _syscall0(type,name) \
 type name(void) \

include/linux/sched.h

@@ -564,6 +564,7 @@ extern int in_egroup_p(gid_t);
 extern void proc_caches_init(void);
 extern void flush_signals(struct task_struct *);
 extern void flush_signal_handlers(struct task_struct *);
+extern void sig_exit(int, int, struct siginfo *);
 extern int dequeue_signal(sigset_t *, siginfo_t *);
 extern void block_all_signals(int (*notifier)(void *priv), void *priv,
 			      sigset_t *mask);
@@ -839,9 +840,14 @@ do {									\
 #define for_each_task(p) \
 	for (p = &init_task ; (p = p->next_task) != &init_task ; )
 
+#define for_each_thread(task) \
+	for (task = next_thread(current) ; task != current ; task = next_thread(task))
+
 #define next_thread(p) \
 	list_entry((p)->thread_group.next, struct task_struct, thread_group)
 
+#define thread_group_leader(p)	(p->pid == p->tgid)
+
 static inline void unhash_process(struct task_struct *p)
 {
 	write_lock_irq(&tasklist_lock);

kernel/fork.c

@@ -724,10 +724,10 @@ int do_fork(unsigned long clone_flags, unsigned long stack_start,
 	/* Need tasklist lock for parent etc handling! */
 	write_lock_irq(&tasklist_lock);
 
-	/* CLONE_PARENT and CLONE_THREAD re-use the old parent */
+	/* CLONE_PARENT re-uses the old parent */
 	p->p_opptr = current->p_opptr;
 	p->p_pptr = current->p_pptr;
-	if (!(clone_flags & (CLONE_PARENT | CLONE_THREAD))) {
+	if (!(clone_flags & CLONE_PARENT)) {
 		p->p_opptr = current;
 		if (!(p->ptrace & PT_PTRACED))
 			p->p_pptr = current;

kernel/signal.c

@@ -142,6 +142,35 @@ flush_signal_handlers(struct task_struct *t)
 	}
 }
 
+/*
+ * sig_exit - cause the current task to exit due to a signal.
+ */
+
+void
+sig_exit(int sig, int exit_code, struct siginfo *info)
+{
+	struct task_struct *t;
+
+	sigaddset(&current->pending.signal, sig);
+	recalc_sigpending(current);
+	current->flags |= PF_SIGNALED;
+
+	/* Propagate the signal to all the tasks in
+	 *  our thread group
+	 */
+	if (info && (unsigned long)info != 1
+	    && info->si_code != SI_TKILL) {
+		read_lock(&tasklist_lock);
+		for_each_thread(t) {
+			force_sig_info(sig, info, t);
+		}
+		read_unlock(&tasklist_lock);
+	}
+
+	do_exit(exit_code);
+	/* NOTREACHED */
+}
+
 /* Notify the system that a driver wants to block all signals for this
  * process, and wants to be notified if any signals at all were to be
  * sent/acted upon.  If the notifier routine returns non-zero, then the
@@ -589,7 +618,7 @@ kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
 		retval = -ESRCH;
 		read_lock(&tasklist_lock);
 		for_each_task(p) {
-			if (p->pgrp == pgrp) {
+			if (p->pgrp == pgrp && thread_group_leader(p)) {
 				int err = send_sig_info(sig, info, p);
 				if (retval)
 					retval = err;
@@ -636,8 +665,15 @@ kill_proc_info(int sig, struct siginfo *info, pid_t pid)
 	read_lock(&tasklist_lock);
 	p = find_task_by_pid(pid);
 	error = -ESRCH;
-	if (p)
+	if (p) {
+		if (!thread_group_leader(p)) {
+                       struct task_struct *tg;
+                       tg = find_task_by_pid(p->tgid);
+                       if (tg)
+                               p = tg;
+                }
 		error = send_sig_info(sig, info, p);
+	}
 	read_unlock(&tasklist_lock);
 	return error;
 }
@@ -660,7 +696,7 @@ static int kill_something_info(int sig, struct siginfo *info, int pid)
 
 		read_lock(&tasklist_lock);
 		for_each_task(p) {
-			if (p->pid > 1 && p != current) {
+			if (p->pid > 1 && p != current && thread_group_leader(p)) {
 				int err = send_sig_info(sig, info, p);
 				++count;
 				if (err != -EPERM)
@@ -985,6 +1021,36 @@ sys_kill(int pid, int sig)
 	return kill_something_info(sig, &info, pid);
 }
 
+/*
+ *  Kill only one task, even if it's a CLONE_THREAD task.
+ */
+asmlinkage long
+sys_tkill(int pid, int sig)
+{
+       struct siginfo info;
+       int error;
+       struct task_struct *p;
+
+       /* This is only valid for single tasks */
+       if (pid <= 0)
+           return -EINVAL;
+
+       info.si_signo = sig;
+       info.si_errno = 0;
+       info.si_code = SI_TKILL;
+       info.si_pid = current->pid;
+       info.si_uid = current->uid;
+
+       read_lock(&tasklist_lock);
+       p = find_task_by_pid(pid);
+       error = -ESRCH;
+       if (p) {
+               error = send_sig_info(sig, &info, p);
+       }
+       read_unlock(&tasklist_lock);
+       return error;
+}
+
 asmlinkage long
 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t *uinfo)
 {