uml: install panic notifier earlier

It turns out that if there's a panic early enough, UML will just sit there in
the LED-blinking loop because the panic notifier hadn't been installed yet.

This patch installs it earlier.

It also fixes the problem which exposed the hang, namely that if you give UML
a zero-sized initrd, it will ask alloc_bootmem for zero bytes, and that will
cause the panic.

While I was in initrd.c, I gave it a style makeover.

Prompted by checkpatch, I moved a couple extern declarations of uml_exitcode
to kern_util.h.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/um/include/kern_util.h b/arch/um/include/kern_util.h
index 625ca29..715ffb5 100644 (file)
--- a/arch/um/include/kern_util.h
+++ b/arch/um/include/kern_util.h
@@ -9,6 +9,8 @@
 #include "sysdep/ptrace.h"
 #include "sysdep/faultinfo.h"
 
+extern int uml_exitcode;
+
 extern int ncpus;
 extern int kmalloc_ok;
 extern int nsyscalls;

diff --git a/arch/um/kernel/initrd.c b/arch/um/kernel/initrd.c
index ae31c62..fa01556 100644 (file)
--- a/arch/um/kernel/initrd.c
+++ b/arch/um/kernel/initrd.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
 
@@ -20,18 +20,27 @@ static int __init read_initrd(void)
        long long size;
        int err;
 
-       if(initrd == NULL)
+       if (initrd == NULL)
                return 0;
 
        err = os_file_size(initrd, &size);
-       if(err)
+       if (err)
                return 0;
 
+       /*
+        * This is necessary because alloc_bootmem craps out if you
+        * ask for no memory.
+        */
+       if (size == 0) {
+               printk(KERN_ERR "\"%\" is a zero-size initrd\n");
+               return 0;
+       }
+
        area = alloc_bootmem(size);
-       if(area == NULL)
+       if (area == NULL)
                return 0;
 
-       if(load_initrd(initrd, area, size) == -1)
+       if (load_initrd(initrd, area, size) == -1)
                return 0;
 
        initrd_start = (unsigned long) area;
@@ -58,13 +67,15 @@ int load_initrd(char *filename, void *buf, int size)
        int fd, n;
 
        fd = os_open_file(filename, of_read(OPENFLAGS()), 0);
-       if(fd < 0){
-               printk("Opening '%s' failed - err = %d\n", filename, -fd);
+       if (fd < 0) {
+               printk(KERN_ERR "Opening '%s' failed - err = %d\n", filename,
+                      -fd);
                return -1;
        }
        n = os_read_file(fd, buf, size);
-       if(n != size){
-               printk("Read of %d bytes from '%s' failed, err = %d\n", size,
+       if (n != size) {
+               printk(KERN_ERR "Read of %d bytes from '%s' failed, "
+                      "err = %d\n", size,
                       filename, -n);
                return -1;
        }

diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 9ba39ab..cb7eef8 100644 (file)
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -223,6 +223,23 @@ static void __init uml_postsetup(void)
        return;
 }
 
+static int panic_exit(struct notifier_block *self, unsigned long unused1,
+                     void *unused2)
+{
+       bust_spinlocks(1);
+       show_regs(&(current->thread.regs));
+       bust_spinlocks(0);
+       uml_exitcode = 1;
+       os_dump_core();
+       return 0;
+}
+
+static struct notifier_block panic_exit_notifier = {
+       .notifier_call          = panic_exit,
+       .next                   = NULL,
+       .priority               = 0
+};
+
 /* Set during early boot */
 unsigned long brk_start;
 unsigned long end_iomem;
@@ -327,6 +344,9 @@ int __init linux_main(int argc, char **argv)
                printf("Kernel virtual memory size shrunk to %lu bytes\n",
                       virtmem_size);
 
+       atomic_notifier_chain_register(&panic_notifier_list,
+                                      &panic_exit_notifier);
+
        uml_postsetup();
 
        stack_protections((unsigned long) &init_thread_info);
@@ -335,29 +355,8 @@ int __init linux_main(int argc, char **argv)
        return start_uml();
 }
 
-extern int uml_exitcode;
-
-static int panic_exit(struct notifier_block *self, unsigned long unused1,
-                     void *unused2)
-{
-       bust_spinlocks(1);
-       show_regs(&(current->thread.regs));
-       bust_spinlocks(0);
-       uml_exitcode = 1;
-       os_dump_core();
-       return 0;
-}
-
-static struct notifier_block panic_exit_notifier = {
-       .notifier_call          = panic_exit,
-       .next                   = NULL,
-       .priority               = 0
-};
-
 void __init setup_arch(char **cmdline_p)
 {
-       atomic_notifier_chain_register(&panic_notifier_list,
-                       &panic_exit_notifier);
        paging_init();
        strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
        *cmdline_p = command_line;

diff --git a/arch/um/os-Linux/main.c b/arch/um/os-Linux/main.c
index de664e7..abb9b0f 100644 (file)
--- a/arch/um/os-Linux/main.c
+++ b/arch/um/os-Linux/main.c
@@ -111,8 +111,6 @@ static void setup_env_path(void)
        }
 }
 
-extern int uml_exitcode;
-
 extern void scan_elf_aux( char **envp);
 
 int __init main(int argc, char **argv, char **envp)