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ipc,msg: drop dst nil validation in copy_msg

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d0edd85283 ("ipc: convert invalid scenarios to use WARN_ON") relaxed the
nil dst parameter check, originally being a full BUG_ON.  However, this
check seems quite unnecessary when the only purpose is for
ceckpoint/restore (MSG_COPY flag):

o The copy variable is set initially to nil, apparently as a way of
  ensuring that prepare_copy is previously called.  Which is in fact done,
  unconditionally at the beginning of do_msgrcv.

o There is no concurrency with 'copy' (stack allocated in do_msgrcv).

Furthermore, any errors in 'copy' (and thus prepare_copy/copy_msg) should
always handled by IS_ERR() family.  Therefore remove this check altogether
as it can never occur with the current users.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Davidlohr Bueso 2015-11-06 16:33:04 -08:00 committed by Linus Torvalds
parent cb7ae262e2
commit 5f2a2d5d42
1 changed files with 0 additions and 1 deletions
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ipc/msgutil.c
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@ -123,7 +123,6 @@ struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
size_t len = src->m_ts;
size_t alen;
WARN_ON(dst == NULL);
if (src->m_ts > dst->m_ts)
return ERR_PTR(-EINVAL);