Re: [PATCH] - Fix memory ordering problem in wake_futex()

Again replying to myself, sorry:

Jack Steiner wrote:

On Fri, Dec 23, 2005 at 11:23:11PM +0100, Manfred Spraul wrote:

Bad race.
Unfortuantely the scenario that you describe is quite frequent:
- autoremove_wake_function()

Not a bug, but for very subtile reasons:

There are no writes to the wait_queue structure except the list_del_init(), and for list_del_init() no memory barriers are required because finish_wait() uses list_empty_careful(), i.e. the spin_lock() is only bypassed if both write operations from list_del_init() have completed.

- ipc/sem.c (search for IN_WAKEUP)

fixed in -rc7.


--
   Manfred
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

---

• References:
  • Re: [PATCH] - Fix memory ordering problem in wake_futex()
    • From: Manfred Spraul <[email protected]>
  • Re: [PATCH] - Fix memory ordering problem in wake_futex()
    • From: Jack Steiner <[email protected]>

• Prev by Date: Re: [EXPERIMENT] Add new "flush" option
• Next by Date: Re: read returns EAGAIN on a _blocking_ socket, but should not? (solved)
• Previous by thread: Re: [PATCH] - Fix memory ordering problem in wake_futex()
• Next by thread: Alert! New security features to all Commonwealth customers! ID# Yukon
• Index(es):
  • Date
  • Thread

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]