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Groups > linux.kernel > #1542801
| From | Colin Ian King <colin.king@canonical.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() |
| Date | 2016-12-15 16:00 +0100 |
| Message-ID | <sOFFM-72d-15@gated-at.bofh.it> (permalink) |
| References | <sOuhj-8sr-5@gated-at.bofh.it> <sOuhj-8sr-9@gated-at.bofh.it> <sOD1g-5AK-23@gated-at.bofh.it> <sOFw6-6Xv-15@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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On 15/12/16 14:42, Boqun Feng wrote:
> On Thu, Dec 15, 2016 at 12:04:59PM +0000, Mark Rutland wrote:
>> On Thu, Dec 15, 2016 at 10:42:03AM +0800, Boqun Feng wrote:
>>> ->qsmask of an RCU leaf node is usually more sparse than the
>>> corresponding cpu_possible_mask. So replace the
>>> for_each_leaf_node_possible_cpu() in force_qs_rnp() with
>>> for_each_leaf_node_cpu() to save several checks.
>>>
>>> [Note we need to use "1UL << bit" instead of "1 << bit" to generate the
>>> corresponding mask for a bit because @mask is unsigned long, this was
>>> spotted by Colin Ian King <colin.king@canonical.com> and CoverityScan in
>>> a previous version of this patch.]
>>
>> Nit: This note can go now that we use leaf_node_cpu_bit(). ;)
>>
>
> I kinda keep this here for honoring the effort of finding out this bug
> from Colin, but yes, it's no longer needed here for the current code.
Yep, remove it.
>
> Regards,
> Boqun
>
>> Thanks,
>> Mark.
>>
>>> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
>>> ---
>>> kernel/rcu/tree.c | 12 +++++-------
>>> 1 file changed, 5 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
>>> index 4e5b81c843de..1ef13e63bc95 100644
>>> --- a/kernel/rcu/tree.c
>>> +++ b/kernel/rcu/tree.c
>>> @@ -3046,13 +3046,11 @@ static void force_qs_rnp(struct rcu_state *rsp,
>>> continue;
>>> }
>>> }
>>> - for_each_leaf_node_possible_cpu(rnp, cpu) {
>>> - unsigned long bit = leaf_node_cpu_bit(rnp, cpu);
>>> - if ((rnp->qsmask & bit) != 0) {
>>> - if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj))
>>> - mask |= bit;
>>> - }
>>> - }
>>> +
>>> + for_each_leaf_node_cpu(rnp, rnp->qsmask, cpu)
>>> + if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj))
>>> + mask |= leaf_node_cpu_bit(rnp, cpu);
>>> +
>>> if (mask != 0) {
>>> /* Idle/offline CPUs, report (releases rnp->lock. */
>>> rcu_report_qs_rnp(mask, rsp, rnp, rnp->gpnum, flags);
>>> --
>>> 2.10.2
>>>
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[RFC v2 0/5] rcu: Introduce for_each_leaf_node_cpu() Boqun Feng <boqun.feng@gmail.com> - 2016-12-15 03:50 +0100
[RFC v2 1/5] rcu: Introduce for_each_leaf_node_cpu() Boqun Feng <boqun.feng@gmail.com> - 2016-12-15 03:50 +0100
Re: [RFC v2 1/5] rcu: Introduce for_each_leaf_node_cpu() Mark Rutland <mark.rutland@arm.com> - 2016-12-15 12:50 +0100
Re: [RFC v2 1/5] rcu: Introduce for_each_leaf_node_cpu() Boqun Feng <boqun.feng@gmail.com> - 2016-12-15 15:40 +0100
Re: [RFC v2 1/5] rcu: Introduce for_each_leaf_node_cpu() Boqun Feng <boqun.feng@gmail.com> - 2016-12-15 16:20 +0100
Re: [RFC v2 1/5] rcu: Introduce for_each_leaf_node_cpu() Mark Rutland <mark.rutland@arm.com> - 2016-12-15 16:20 +0100
[RFC v2.1 1/5] rcu: Introduce for_each_leaf_node_cpu() Boqun Feng <boqun.feng@gmail.com> - 2016-12-15 16:30 +0100
Re: [RFC v2.1 1/5] rcu: Introduce for_each_leaf_node_cpu() Mark Rutland <mark.rutland@arm.com> - 2016-12-15 16:40 +0100
[RFC v2 2/5] rcu: Use for_each_leaf_node_cpu() in RCU stall checking Boqun Feng <boqun.feng@gmail.com> - 2016-12-15 03:50 +0100
[RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() Boqun Feng <boqun.feng@gmail.com> - 2016-12-15 03:50 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() Mark Rutland <mark.rutland@arm.com> - 2016-12-15 13:10 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() Boqun Feng <boqun.feng@gmail.com> - 2016-12-15 15:50 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() Colin Ian King <colin.king@canonical.com> - 2016-12-15 16:00 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() Boqun Feng <boqun.feng@gmail.com> - 2016-12-19 16:20 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-20 06:10 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() Boqun Feng <boqun.feng@gmail.com> - 2016-12-20 07:00 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() Boqun Feng <boqun.feng@gmail.com> - 2016-12-20 09:20 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-20 16:40 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-20 16:30 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() Boqun Feng <boqun.feng@gmail.com> - 2016-12-21 03:40 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-21 04:50 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() Boqun Feng <boqun.feng@gmail.com> - 2016-12-21 05:20 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-21 17:50 +0100
Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() Boqun Feng <boqun.feng@gmail.com> - 2016-12-22 02:10 +0100
[RFC v2 5/5] rcu: Use for_each_leaf_node_cpu() in online CPU iteration Boqun Feng <boqun.feng@gmail.com> - 2016-12-15 03:50 +0100
[RFC v2 3/5] rcu: Use for_each_leaf_node_cpu() in ->expmask iteration Boqun Feng <boqun.feng@gmail.com> - 2016-12-15 03:50 +0100
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