Re: [PATCH 1/1] wait: using uninitialized member of wait queue

Michał Nazarewicz
2010-10-05T10:39:46Z

On Tue, 05 Oct 2010 10:47:57 +0200, Evgeny Kuznetsov <EXT-Eugeny.Kuznetsov@nokia.com> wrote:
> Member "flags" of "wait_queue_t" struct is used in several places in
> kernel code without beeing initialized. "flags" is used in bitwise operations.
^^^^^^ -- "being"

> If "flags" not initialized then unexpected behaviour may have place.
> Incorrect flags maybe used later in code.
> Struct "wait_queue_t" is initialized in function "init_wait()". But
> "init_wait()" do not initialize "flag" member.
^^ -- does ^^^^ -- "flags"

> Added initialization of "wait_queue_t.flags" with zero value into "init_wait".

> diff --git a/include/linux/wait.h b/include/linux/wait.h
> index 0836ccc..3efc9f3 100644
> --- a/include/linux/wait.h
> +++ b/include/linux/wait.h
> @@ -614,6 +614,7 @@ int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
> (wait)->private = current; \
> (wait)->func = autoremove_wake_function; \
> INIT_LIST_HEAD(&(wait)->task_list); \
> + (wait)->flags = 0; \
> } while (0)
> /**

I'd turn init_wait() into a static inline. Otherwise looks good to me.
(Interestingly, init_wait() is used only in 3 places in the kernel and
none uses flags.)

--
Best regards, _ _
| Humble Liege of Serenely Enlightened Majesty of o' \,=./ `o
| Computer Science, Michał "mina86" Nazarewicz (o o)
+----[mina86*mina86.com]---[mina86*jabber.org]----ooO--(_)--Ooo--