[50/65] netns: Fail conspicously if someone uses net_generic at an inappropriate time.

From: Greg KH
Date: Wed Feb 01 2012 - 16:09:00 EST

3.0-stable review patch. If anyone has any objections, please let me know.


From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>

[ Upstream commit 5ee4433efe99b9f39f6eff5052a177bbcfe72cea ]

By definition net_generic should never be called when it can return
NULL. Fail conspicously with a BUG_ON to make it clear when people mess
up that a NULL return should never happen.

Recently there was a bug in the CAIF subsystem where it was registered
with register_pernet_device instead of register_pernet_subsys. It was
erroneously concluded that net_generic could validly return NULL and
that net_assign_generic was buggy (when it was just inefficient).
Hopefully this BUG_ON will prevent people to coming to similar erroneous
conclusions in the futrue.

Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Tested-by: Sasha Levin <levinsasha928@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
include/net/netns/generic.h | 1 +
1 file changed, 1 insertion(+)

--- a/include/net/netns/generic.h
+++ b/include/net/netns/generic.h
@@ -41,6 +41,7 @@ static inline void *net_generic(const st
ptr = ng->ptr[id - 1];

+ BUG_ON(!ptr);
return ptr;

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