On 08/17/2012 09:17 AM, Herton Ronaldo Krzesinski wrote:
On Wed, Aug 15, 2012 at 03:47:33PM -0400, Paul Gortmaker wrote:
From: John Stultz <john.stu...@linaro.org>
-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------
commit 6b43ae8a619d17c4935c3320d2ef9e92bdeed05d upstream.
This should have been backported when it was commited, but I
mistook the problem as requiring the ntp_lock changes
that landed in 3.4 in order for it to occur.
Unfortunately the same issue can happen (with only one cpu)
as follows:
do_adjtimex()
write_seqlock_irq(&xtime_lock);
process_adjtimex_modes()
process_adj_status()
ntp_start_leap_timer()
hrtimer_start()
hrtimer_reprogram()
tick_program_event()
clockevents_program_event()
ktime_get()
seq = req_seqbegin(xtime_lock); [DEADLOCK]
This deadlock will no always occur, as it requires the
leap_timer to force a hrtimer_reprogram which only happens
if its set and there's no sooner timer to expire.
[...]
I remember this came through the leapsecond deadlock & hrtimer/futex
issue fixes. But I noted now commit 6b1859dba01c7d512b72d77e3fd7da8354235189
("ntp: Fix STA_INS/DEL clearing bug") was not included, and its changelog
says it fixes a problem introduced with this. Wouldn't it be worth/right to
also include it in 2.6.34? I didn't test etc., just detected through the
changelog/description but would expect it would be affected too. I also
noted it is missing from 3.2.y and 2.6.32.y stables, and perhaps should be
scheduled for inclusion in their cases too.
Yes. I also have another change pending in -tip that I've marked for
stable. Once that lands I'm planning on reviewing the current stable
trees to check that they have all the needed changes.
thanks
-john
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
