[JAUNTY SRU] UBUNTU: SAUCE: added memory barrier to prevent a reference counter leak.
manoj.iyer at canonical.com
manoj.iyer at canonical.com
Thu Jul 23 20:29:07 UTC 2009
smb,
The lock used to be there before they used lock bitops to get the desired
memory ordering. But this memory barrier was removed after 2.6.27 when
BH_Lock was introduced in the code. smp_mb__before_clear_bit(); was
removed and smp_mb__after_clear_bit() was kept after clear_bit_unlock()
call. Not sure is this introduced a regression, which shows up in some
cases.
The following shaid removed the above mentioned smp_mb__before_clear_bit()
memory barrier.
SHAID: 51b07fc3c5c830bb49c80fc5eac041e1f66a72e7
Like I mentioned in the patch this seems to be only in the RH errata and
some custom kernels based on RHEL4, and not mentioned in lkml.
Cheers
--- manjo
On Thu, 23 Jul 2009, Stefan Bader wrote:
> I think this should be save to add without causing regressions. And I think
> you said some problems were solved by that. Just for general understanding,
> if this really addresses one of the problems, what is the reason this is only
> a Redhad erata and not gone upstream?
>
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