On Tue, 7 Jul 2015 17:18:40 -0400
Vivek Goyal <vgo...@redhat.com> wrote:

> On Thu, Jul 02, 2015 at 09:45:52AM +0800, Minfei Huang wrote:

[snip]

> I am thinking of moving kernel loading code in a separate function to
> make things little simpler. Right now it is confusing.
> 
> Can you please test attached patch. I have only compile tested it. This
> is primarily doing what you are doing but in a separate function. It
> seems more readable now.

The patch looks good to me. What about the following patch on top
to make things even more readable?
---
 kernel/kexec.c |   50 +++++++++++++++++---------------------------------
 1 file changed, 17 insertions(+), 33 deletions(-)

--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1236,14 +1236,18 @@ int kexec_load_disabled;
 
 static DEFINE_MUTEX(kexec_mutex);
 
-static int __kexec_load(struct kimage **rimage, unsigned long entry,
-                       unsigned long nr_segments,
+static int __kexec_load(unsigned long entry, unsigned long nr_segments,
                        struct kexec_segment __user * segments,
                        unsigned long flags)
 {
+       struct kimage *image, **dest_image;
        unsigned long i;
        int result;
-       struct kimage *image;
+
+       dest_image = (flags & KEXEC_ON_CRASH) ? &kexec_crash_image : 
&kexec_image;
+
+       if (nr_segments == 0)
+               return 0;
 
        if (flags & KEXEC_ON_CRASH) {
                /*
@@ -1251,7 +1255,6 @@ static int __kexec_load(struct kimage **
                 * crashes.  Free any current crash dump kernel before
                 * we corrupt it.
                 */
-
                kimage_free(xchg(&kexec_crash_image, NULL));
        }
 
@@ -1267,30 +1270,29 @@ static int __kexec_load(struct kimage **
 
        result = machine_kexec_prepare(image);
        if (result)
-               goto out;
+               goto fail;
 
        for (i = 0; i < nr_segments; i++) {
                result = kimage_load_segment(image, &image->segment[i]);
                if (result)
-                       goto out;
+                       goto fail;
        }
-
        kimage_terminate(image);
-       *rimage = image;
-out:
+       /* Install the new kernel, and  uninstall the old */
+       kimage_free(xchg(dest_image, image));
        if (flags & KEXEC_ON_CRASH)
                crash_unmap_reserved_pages();
-
-       /* Free image if there was an error */
-       if (result)
-               kimage_free(image);
+       return 0;
+fail:
+       if (flags & KEXEC_ON_CRASH)
+               crash_unmap_reserved_pages();
+       kimage_free(image);
        return result;
 }
 
 SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
                struct kexec_segment __user *, segments, unsigned long, flags)
 {
-       struct kimage **dest_image, *image;
        int result;
 
        /* We only trust the superuser with rebooting the system. */
@@ -1315,9 +1317,6 @@ SYSCALL_DEFINE4(kexec_load, unsigned lon
        if (nr_segments > KEXEC_SEGMENT_MAX)
                return -EINVAL;
 
-       image = NULL;
-       result = 0;
-
        /* Because we write directly to the reserved memory
         * region when loading crash kernels we need a mutex here to
         * prevent multiple crash  kernels from attempting to load
@@ -1329,24 +1328,9 @@ SYSCALL_DEFINE4(kexec_load, unsigned lon
        if (!mutex_trylock(&kexec_mutex))
                return -EBUSY;
 
-       dest_image = &kexec_image;
-       if (flags & KEXEC_ON_CRASH)
-               dest_image = &kexec_crash_image;
-
        /* Load new kernel */
-       if (nr_segments > 0) {
-               result = __kexec_load(&image, entry, nr_segments, segments,
-                                     flags);
-               if (result)
-                       goto out;
-       }
-
-       /* Install the new kernel, and  Uninstall the old */
-       image = xchg(dest_image, image);
-
-out:
+       result = __kexec_load(entry, nr_segments, segments, flags);
        mutex_unlock(&kexec_mutex);
-       kimage_free(image);
 
        return result;
 }

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