[PATCH] uml: Turn literal numbers into symbolic constants

So, there I was, looking at my own code, wondering what the magic setjmp
return values did.  This patch turns the constants that are used to make
requests of the initial thread into meaningful symbols.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/kernel/skas/process.c

@@ -201,6 +201,11 @@ void userspace(union uml_pt_regs *regs)
 		}
 	}
 }
+#define INIT_JMP_NEW_THREAD 0
+#define INIT_JMP_REMOVE_SIGSTACK 1
+#define INIT_JMP_CALLBACK 2
+#define INIT_JMP_HALT 3
+#define INIT_JMP_REBOOT 4
 
 void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
 		void (*handler)(int))
@@ -236,7 +241,7 @@ void thread_wait(void *sw, void *fb)
 	*switch_buf = &buf;
 	fork_buf = fb;
 	if(sigsetjmp(buf, 1) == 0)
-		siglongjmp(*fork_buf, 1);
+		siglongjmp(*fork_buf, INIT_JMP_REMOVE_SIGSTACK);
 }
 
 void switch_threads(void *me, void *next)
@@ -266,21 +271,25 @@ int start_idle_thread(void *stack, void *switch_buf_ptr, void **fork_buf_ptr)
 
 	*fork_buf_ptr = &initial_jmpbuf;
 	n = sigsetjmp(initial_jmpbuf, 1);
-	if(n == 0)
-		new_thread_proc((void *) stack, new_thread_handler);
-	else if(n == 1)
-		remove_sigstack();
-	else if(n == 2){
+        switch(n){
+        case INIT_JMP_NEW_THREAD:
+                new_thread_proc((void *) stack, new_thread_handler);
+                break;
+        case INIT_JMP_REMOVE_SIGSTACK:
+                remove_sigstack();
+                break;
+        case INIT_JMP_CALLBACK:
 		(*cb_proc)(cb_arg);
 		siglongjmp(*cb_back, 1);
-	}
-	else if(n == 3){
+                break;
+        case INIT_JMP_HALT:
 		kmalloc_ok = 0;
 		return(0);
-	}
-	else if(n == 4){
+        case INIT_JMP_REBOOT:
 		kmalloc_ok = 0;
 		return(1);
+        default:
+                panic("Bad sigsetjmp return in start_idle_thread - %d\n", n);
 	}
 	siglongjmp(**switch_buf, 1);
 }
@@ -305,7 +314,7 @@ void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 
 	block_signals();
 	if(sigsetjmp(here, 1) == 0)
-		siglongjmp(initial_jmpbuf, 2);
+		siglongjmp(initial_jmpbuf, INIT_JMP_CALLBACK);
 	unblock_signals();
 
 	cb_proc = NULL;
@@ -316,13 +325,13 @@ void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 void halt_skas(void)
 {
 	block_signals();
-	siglongjmp(initial_jmpbuf, 3);
+	siglongjmp(initial_jmpbuf, INIT_JMP_HALT);
 }
 
 void reboot_skas(void)
 {
 	block_signals();
-	siglongjmp(initial_jmpbuf, 4);
+	siglongjmp(initial_jmpbuf, INIT_JMP_REBOOT);
 }
 
 void switch_mm_skas(int mm_fd)