Add "restart" system call, allowing system calls to restart after signal

handling.

Update x86 to use the new infrastructure.

arch/i386/kernel/cpu/intel.c

@@ -3,8 +3,9 @@
 #include <linux/string.h>
 #include <linux/bitops.h>
 #include <linux/smp.h>
+#include <linux/thread_info.h>
+
 #include <asm/processor.h>
-#include <asm/thread_info.h>
 #include <asm/msr.h>
 #include <asm/uaccess.h>
 

arch/i386/kernel/cpu/mcheck/mce.c

@@ -7,9 +7,10 @@
 #include <linux/kernel.h>
 #include <linux/config.h>
 #include <linux/smp.h>
+#include <linux/thread_info.h>
+
 #include <asm/processor.h> 
 #include <asm/system.h>
-#include <asm/thread_info.h>
 
 #include "mce.h"
 

arch/i386/kernel/entry.S

@@ -484,7 +484,7 @@ ENTRY(spurious_interrupt_bug)
 
 .data
 ENTRY(sys_call_table)
-	.long sys_ni_syscall	/* 0 - old "setup()" system call*/
+	.long sys_restart_syscall	/* 0 - old "setup()" system call, used for restarting */
 	.long sys_exit
 	.long sys_fork
 	.long sys_read

arch/i386/kernel/signal.c

@@ -506,6 +506,8 @@ handle_signal(unsigned long sig, siginfo_t *info, sigset_t *oldset,
 	if (regs->orig_eax >= 0) {
 		/* If so, check system call restarting.. */
 		switch (regs->eax) {
+		        case -ERESTART_RESTARTBLOCK:
+				current_thread_info()->restart_block.fn = do_no_restart_syscall;
 			case -ERESTARTNOHAND:
 				regs->eax = -EINTR;
 				break;
@@ -591,6 +593,10 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 			regs->eax = regs->orig_eax;
 			regs->eip -= 2;
 		}
+		if (regs->eax == -ERESTART_RESTARTBLOCK){
+			regs->eax = __NR_restart_syscall;
+			regs->eip -= 2;
+		}
 	}
 	return 0;
 }

arch/i386/oprofile/nmi_int.c

@@ -13,7 +13,7 @@
 #include <linux/smp.h>
 #include <linux/oprofile.h>
 #include <linux/pm.h>
-#include <asm/thread_info.h>
+#include <linux/thread_info.h>
 #include <asm/nmi.h>
 #include <asm/ptrace.h>
 #include <asm/msr.h>

include/asm-i386/current.h

 #ifndef _I386_CURRENT_H
 #define _I386_CURRENT_H
 
-#include <asm/thread_info.h>
+#include <linux/thread_info.h>
 
 struct task_struct;
 

include/asm-i386/thread_info.h

@@ -20,6 +20,7 @@
  * - if the contents of this structure are changed, the assembly constants must also be changed
  */
 #ifndef __ASSEMBLY__
+
 struct thread_info {
 	struct task_struct	*task;		/* main task structure */
 	struct exec_domain	*exec_domain;	/* execution domain */
@@ -31,6 +32,7 @@ struct thread_info {
 					 	   0-0xBFFFFFFF for user-thead
 						   0-0xFFFFFFFF for kernel-thread
 						*/
+	struct restart_block    restart_block;
 
 	__u8			supervisor_stack[0];
 };
@@ -44,6 +46,7 @@ struct thread_info {
 #define TI_CPU		0x0000000C
 #define TI_PRE_COUNT	0x00000010
 #define TI_ADDR_LIMIT	0x00000014
+#define TI_RESTART_BLOCK 0x0000018
 
 #endif
 
@@ -55,6 +58,7 @@ struct thread_info {
  * preempt_count needs to be 1 initially, until the scheduler is functional.
  */
 #ifndef __ASSEMBLY__
+
 #define INIT_THREAD_INFO(tsk)			\
 {						\
 	.task		= &tsk,			\
@@ -63,6 +67,9 @@ struct thread_info {
 	.cpu		= 0,			\
 	.preempt_count	= 1,			\
 	.addr_limit	= KERNEL_DS,		\
+	.restart_block = {			\
+		.fn = do_no_restart_syscall,	\
+	},					\
 }
 
 #define init_thread_info	(init_thread_union.thread_info)

include/asm-i386/unistd.h

@@ -5,6 +5,7 @@
  * This file contains the system call numbers.
  */
 
+#define __NR_restart_syscall      0
 #define __NR_exit		  1
 #define __NR_fork		  2
 #define __NR_read		  3

include/linux/errno.h

@@ -10,6 +10,7 @@
 #define ERESTARTNOINTR	513
 #define ERESTARTNOHAND	514	/* restart if no handler.. */
 #define ENOIOCTLCMD	515	/* No ioctl command */
+#define ERESTART_RESTARTBLOCK 516 /* restart by calling sys_restart_syscall */
 
 /* Defined for the NFSv3 protocol */
 #define EBADHANDLE	521	/* Illegal NFS file handle */

include/linux/thread_info.h

@@ -7,6 +7,16 @@
 #ifndef _LINUX_THREAD_INFO_H
 #define _LINUX_THREAD_INFO_H
 
+/*
+ * System call restart block. 
+ */
+struct restart_block {
+	long (*fn)(struct restart_block *);
+	unsigned long arg0, arg1, arg2;
+};
+
+extern long do_no_restart_syscall(struct restart_block *parm);
+
 #include <linux/bitops.h>
 #include <asm/thread_info.h>
 

kernel/signal.c

@@ -1351,6 +1351,18 @@ EXPORT_SYMBOL(unblock_all_signals);
  * System call entry points.
  */
 
+asmlinkage long sys_restart_syscall(void)
+{
+	struct thread_info *thread = current_thread_info();
+	return thread->restart_block.fn(&thread->restart_block);
+}
+
+long do_no_restart_syscall(struct restart_block *param)
+{
+	return -EINTR;
+}
+
+
 /*
  * We don't need to get the kernel lock - this is all local to this
  * particular thread.. (and that's good, because this is _heavily_