powerpc/nvram64: Need return the related error code on failure occurs

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').

Also set ret value when only need it, so can save structions for normal
cases.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
index 48fbc2b..8213ee1 100644 (file)
--- a/arch/powerpc/kernel/nvram_64.c
+++ b/arch/powerpc/kernel/nvram_64.c
@@ -84,22 +84,30 @@ static ssize_t dev_nvram_read(struct file *file, char __user *buf,
        char *tmp = NULL;
        ssize_t size;
 
-       ret = -ENODEV;
-       if (!ppc_md.nvram_size)
+       if (!ppc_md.nvram_size) {
+               ret = -ENODEV;
                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 = 0;
                goto out;
+       }
 
        count = min_t(size_t, count, size - *ppos);
        count = min(count, PAGE_SIZE);
 
-       ret = -ENOMEM;
        tmp = kmalloc(count, GFP_KERNEL);
-       if (!tmp)
+       if (!tmp) {
+               ret = -ENOMEM;
                goto out;
+       }
 
        ret = ppc_md.nvram_read(tmp, count, ppos);
        if (ret <= 0)