• Doug Ledford's avatar
    ipc/mqueue: correct mq_attr_ok test · 2c12ea49
    Doug Ledford authored
    While working on the other parts of the mqueue stuff, I noticed that the
    calculation for overflow in mq_attr_ok didn't actually match reality (this
    is especially true since my last patch which changed how we account memory
    slightly).
    
    In particular, we used to test for overflow using:
      msgs * msgsize + msgs * sizeof(struct msg_msg *)
    
    That was never really correct because each message we allocate via
    load_msg() is actually a struct msg_msg followed by the data for the
    message (and if struct msg_msg + data exceeds PAGE_SIZE we end up
    allocating struct msg_msgseg structs too, but accounting for them would
    get really tedious, so let's ignore those...they're only a pointer in size
    anyway).  This patch updates the calculation to be more accurate in
    regards to maximum possible memory consumption by the mqueue.
    
    [akpm@linux-foundation.org: add a local to simplify overflow-checking expression]
    Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
    Cc: Stephen Rothwell <sfr@canb.auug.org.au>
    Cc: Manfred Spraul <manfred@colorfullife.com>
    Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    2c12ea49
mqueue.c 33.9 KB