When error occurs, need return the related error code to let upper
caller know about it.

ppc_md.nvram_size() can return the error code (e.g. core99_nvram_size()
in 'arch/powerpc/platforms/powermac/nvram.c').

And when '*ppos >= size', need return -ESPIPE (Illegal seek)

The original related patch: "f9ce299 [PATCH] powerpc: fix large nvram
access"


Signed-off-by: Chen Gang <gang.c...@asianux.com>
---
 arch/powerpc/kernel/nvram_64.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
index 48fbc2b..db2a636 100644
--- a/arch/powerpc/kernel/nvram_64.c
+++ b/arch/powerpc/kernel/nvram_64.c
@@ -88,10 +88,15 @@ static ssize_t dev_nvram_read(struct file *file, char 
__user *buf,
        if (!ppc_md.nvram_size)
                goto out;
 
-       ret = 0;
        size = ppc_md.nvram_size();
-       if (*ppos >= size || size < 0)
+       if (size < 0) {
+               ret = size;
                goto out;
+       }
+       if (*ppos >= size) {
+               ret = -ESPIPE;
+               goto out;
+       }
 
        count = min_t(size_t, count, size - *ppos);
        count = min(count, PAGE_SIZE);
-- 
1.7.7.6
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