On Fri, Feb 26, 2016 at 07:57:55PM +0800, Dave Young wrote:
> 2nd kernel hangs early because of a regression caused by below commit:
> commit 68262155d8c661586b809bc5301a7dff1c378137
> Author: Andrew Jones <drjones at redhat.com>
> Date: Fri Nov 20 12:31:53 2015 -0500
>
> kexec/fs2dt: cleanup pathname
>
> putnode() will add the trailing '/', avoid having two. Also
> pathstart is unused, get rid of it.
>
> Signed-off-by: Andrew Jones <drjones at redhat.com>
> Signed-off-by: Simon Horman <horms at verge.net.au>
>
> The actual purpose of the commit is to avoid double slash in pathname.
> But unfortunately in function putnode() we have below magics to get the node
> name:
> basename = strrchr(pathname,'/') + 1;
> ...
> strcpy((void *)dt, *basename ? basename : "");
> ...
> strcat(pathname, "/");
>
> We treat none zero basename as a node name, then concat a slash to open the
> directory for later property handling.
> pathname originally was "/proc/device-tree/" so for the first run of putnode
> it will cause double slashes. With the commit above mentioned there are no
> double slashes but we will copy "device-tree" to dt. Thus kexec kernel is not
> happy..
>
> Instead let's fix it by only concating slash when the basenanme is not empty
> and restore the initial value of pathname as "/proc/device-tree/"
>
> Note: I only reproduce the issue with loading older kernel like 3.10 in RHEL. I do
> not see the problem in new kernels in Fedora.
>
> Signed-off-by: Dave Young <dyoung at redhat.com>
Err.. sorry I missed that strrchr() for the basename.
Reviewed-by: Andrew Jones <drjones at redhat.com>
> ---
> kexec/fs2dt.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> --- kexec-tools.orig/kexec/fs2dt.c
> +++ kexec-tools/kexec/fs2dt.c
> @@ -577,7 +577,8 @@ static void putnode(void)
> strcpy((void *)dt, *basename ? basename : "");
> dt += ((plen + 4)/4);
>
> - strcat(pathname, "/");
> + if (*basename)
> + strcat(pathname, "/");
> dn = pathname + strlen(pathname);
>
> putprops(dn, namelist, numlist);
> @@ -804,7 +805,7 @@ static void add_boot_block(char **bufp,
>
> void create_flatten_tree(char **bufp, off_t *sizep, const char *cmdline)
> {
> - strcpy(pathname, "/proc/device-tree");
> + strcpy(pathname, "/proc/device-tree/");
>
> dt_cur_size = INIT_TREE_WORDS;
> dt_base = malloc(dt_cur_size*4);
