[PATCH] net/dns_resolver: dns_query Modify parameter checking to avoid dead code

[nixiaoming]

After commit 1a4240f4764a ("DNS: Separate out CIFS DNS Resolver code")
a dead code exists in function dns_query

code show as below:
        if (!name || namelen == 0)
                return -EINVAL;
        /*Now the value of "namelen" cannot be equal to 0*/
        ....
        if (!namelen) /*The condition "!namelen"" cannot be true*/
                namelen = strnlen(name, 256); /*deadcode*/

Modify parameter checking to avoid dead code

Signed-off-by: nixiaoming <nixiaom...@huawei.com>
---
 net/dns_resolver/dns_query.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/net/dns_resolver/dns_query.c b/net/dns_resolver/dns_query.c
index 49da670..f2acee2 100644
--- a/net/dns_resolver/dns_query.c
+++ b/net/dns_resolver/dns_query.c
@@ -81,7 +81,9 @@ int dns_query(const char *type, const char *name, size_t 
namelen,
        kenter("%s,%*.*s,%zu,%s",
               type, (int)namelen, (int)namelen, name, namelen, options);
 
-       if (!name || namelen == 0)
+       if (!name || namelen < 3 || namelen > 255)
+               return -EINVAL;
+       if (namelen > strnlen(name, 256)) /*maybe only need part of name*/
                return -EINVAL;
 
        /* construct the query key description as "[<type>:]<name>" */
@@ -94,10 +96,6 @@ int dns_query(const char *type, const char *name, size_t 
namelen,
                desclen += typelen + 1;
        }
 
-       if (!namelen)
-               namelen = strnlen(name, 256);
-       if (namelen < 3 || namelen > 255)
-               return -EINVAL;
        desclen += namelen + 1;
 
        desc = kmalloc(desclen, GFP_KERNEL);
-- 
2.10.1