On Fri, 10 Jul 2015 13:12:17 +0800
Minfei Huang <mnfhu...@gmail.com> wrote:

> For some arch, kexec shall map the reserved pages, then use them, when
> we try to start the kdump service.
> 
> Now kexec will never unmap the reserved pages, once it fails to continue
> starting the kdump service. So we make a pair of map/unmap reserved
> pages whatever kexec fails or not in code path.
> 
> In order to make code readable, wrap a new function __kexec_load which
> contains all of the logic to deal with the image loading.
> 
> Signed-off-by: Minfei Huang <mnfhu...@gmail.com>
> ---
> v3:
> - reconstruct the patch, wrap a new function to deal with the code logic, 
> based on Vivek and Michael's patch
> v2:
> - replace the "failure" label with "fail_unmap_pages"
> v1:
> - reconstruct the patch code
> ---
>  kernel/kexec.c | 112 
> ++++++++++++++++++++++++++++++++-------------------------
>  1 file changed, 63 insertions(+), 49 deletions(-)
> 
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index a785c10..2232c90 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -1247,10 +1247,71 @@ int kexec_load_disabled;
> 
>  static DEFINE_MUTEX(kexec_mutex);
> 
> +static int __kexec_load(unsigned long entry, unsigned long nr_segments,
> +                     struct kexec_segment __user *segments,
> +                     unsigned long flags)
> +{
> +     int result = 0;
> +     struct kimage **dest_image, *image;
> +
> +     dest_image = &kexec_image;
> +
> +     if (flags & KEXEC_ON_CRASH)
> +             dest_image = &kexec_crash_image;
> +
> +     if (nr_segments == 0) {
> +             /* Install the new kernel, and  Uninstall the old */
> +             image = xchg(dest_image, image);
> +             kimage_free(image);

Well this is wrong and should probably be:

        if (nr_segments == 0) {
                /* Uninstall image */
                image = xchg(dest_image, NULL);
                kimage_free(image);

> +     } else {
> +             unsigned long i;
> +
> +             if (flags & KEXEC_ON_CRASH) {
> +                     /*

[snip]

> +                     result = kimage_load_segment(image, &image->segment[i]);
> +                     if (result)
> +                             goto failure_unmap_mem;
> +             }
> +
> +             kimage_terminate(image);
> +
> +             /* Install the new kernel, and  Uninstall the old */

Perhaps fix the comment: Remove superfluous blank and lowercase "uninstall"?

> +             image = xchg(dest_image, image);
> +
> +failure_unmap_mem:
> +             if (flags & KEXEC_ON_CRASH)
> +                     crash_unmap_reserved_pages();
> +             kimage_free(image);

Here the update patch:
---
diff --git a/kernel/kexec.c b/kernel/kexec.c
index e686a39..2f5b4aa 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1249,8 +1249,8 @@ static int __kexec_load(unsigned long entry, unsigned 
long nr_segments,
                dest_image = &kexec_crash_image;
 
        if (nr_segments == 0) {
-               /* Install the new kernel, and  Uninstall the old */
-               image = xchg(dest_image, image);
+               /* Uninstall image */
+               image = xchg(dest_image, NULL);
                kimage_free(image);
        } else {
                unsigned long i;
@@ -1287,7 +1287,7 @@ static int __kexec_load(unsigned long entry, unsigned 
long nr_segments,
 
                kimage_terminate(image);
 
-               /* Install the new kernel, and  Uninstall the old */
+               /* Install the new kernel, and uninstall the old */
                image = xchg(dest_image, image);
 
 failure_unmap_mem:

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