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lockdep: fix kernel crash on module unload 

Michael Wu noticed in his lkml post at

    http://marc.info/?l=linux-kernel&m=119396182726091&w=2

that certain wireless drivers ended up having their name in module
memory, which would then crash the kernel on module unload.

The patch he proposed was a bit clumsy in that it increased the size of
a lockdep entry significantly; the patch below tries another approach,
it checks, on module teardown, if the name of a class is in module space
and then zaps the class.  This is very similar to what we already do
with keys that are in module space.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Arjan van de Ven 2008-01-24 07:00:45 +01:00 committed by Linus Torvalds
parent 4784b11c4f
commit fabe874a48
1 changed files with 5 additions and 2 deletions
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7
kernel/lockdep.c
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@ -2932,7 +2932,7 @@ static void zap_class(struct lock_class *class)
} }
static inline int within(void *addr, void *start, unsigned long size) static inline int within(const void *addr, void *start, unsigned long size)
{ {
return addr >= start && addr < start + size; return addr >= start && addr < start + size;
} }
@ -2955,9 +2955,12 @@ void lockdep_free_key_range(void *start, unsigned long size)
head = classhash_table + i; head = classhash_table + i;
if (list_empty(head)) if (list_empty(head))
continue; continue;
list_for_each_entry_safe(class, next, head, hash_entry) list_for_each_entry_safe(class, next, head, hash_entry) {
if (within(class->key, start, size)) if (within(class->key, start, size))
zap_class(class); zap_class(class);
else if (within(class->name, start, size))
zap_class(class);
}
} }
if (locked) if (locked)