From: Rao Shoaib <rao.shoaib@oracle.com>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>,
linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com,
brouer@redhat.com, linux-mm@kvack.org
Subject: Re: [PATCH 1/2] Move kfree_call_rcu() to slab_common.c
Date: Thu, 4 Jan 2018 13:27:49 -0800 [thread overview]
Message-ID: <64ca3929-4044-9393-a6ca-70c0a2589a35@oracle.com> (raw)
In-Reply-To: <be1abd24-56c8-45bc-fecc-3f0c5b978678@oracle.com>
On 01/04/2018 12:35 PM, Rao Shoaib wrote:
> Hi Boqun,
>
> Thanks a lot for all your guidance and for catching the cut and paster
> error. Please see inline.
>
>
> On 01/03/2018 05:38 PM, Boqun Feng wrote:
>>
>> But you introduced a bug here, you should use rcu_state_p instead of
>> &rcu_sched_state as the third parameter for __call_rcu().
>>
>> Please re-read:
>>
>> https://marc.info/?l=linux-mm&m=151390529209639
>>
>> , and there are other comments, which you still haven't resolved in this
>> version. You may want to write a better commit log to explain the
>> reasons of each modifcation and fix bugs or typos in your previous
>> version. That's how review process works ;-)
>>
>> Regards,
>> Boqun
>>
> This is definitely a serious error. Thanks for catching this.
>
> As far as your previous comments are concerned, only the following one
> has not been addressed. Can you please elaborate as I do not
> understand the comment. The code was expanded because the new macro
> expansion check fails. Based on Matthew Wilcox's comment I have
> reverted rcu_head_name back to rcu_head.
It turns out I did not remember the real reason for the change. With the
macro rewritten, using rcu_head as a macro argument does not work
because it conflicts with the name of the type 'struct rcu_head' used in
the macro. I have renamed the macro argument to rcu_name.
Shoaib
>
>> +#define kfree_rcu(ptr, rcu_head_name) \
>> + do { \
>> + typeof(ptr) __ptr = ptr; \
>> + unsigned long __off = offsetof(typeof(*(__ptr)), \
>> + rcu_head_name); \
>> + struct rcu_head *__rptr = (void *)__ptr + __off; \
>> + __kfree_rcu(__rptr, __off); \
>> + } while (0)
>
> why do you want to open code this?
>
> Does the following text for the commit log looks better.
>
> kfree_rcu() should use the new kfree_bulk() interface for freeing rcu
> structures
>
> The newly implemented kfree_bulk() interfaces are more efficient,
> using the interfaces for freeing rcu structures has shown performance
> improvements in synthetic benchmarks that allocate and free rcu
> structures at a high rate.
>
> Shoaib
>
> --
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next prev parent reply other threads:[~2018-01-04 21:33 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-02 20:11 [PATCH 1/2] Move kfree_call_rcu() to slab_common.c rao.shoaib
2018-01-02 20:11 ` [PATCH 2/2] kfree_rcu() should use the new kfree_bulk() interface for freeing rcu structures rao.shoaib
2018-01-02 22:23 ` [PATCH 1/2] Move kfree_call_rcu() to slab_common.c Matthew Wilcox
2018-01-02 22:49 ` Rao Shoaib
2018-01-04 1:38 ` Boqun Feng
2018-01-04 20:35 ` Rao Shoaib
2018-01-04 21:27 ` Rao Shoaib [this message]
2018-01-04 21:46 ` Matthew Wilcox
2018-01-04 22:18 ` Rao Shoaib
2018-01-04 23:13 ` Matthew Wilcox
2018-01-04 23:47 ` Paul E. McKenney
2018-01-05 0:07 ` Matthew Wilcox
2018-01-05 2:14 ` Rao Shoaib
2018-01-05 6:46 ` Joe Perches
2018-03-27 1:56 ` Rao Shoaib
2018-03-27 2:06 ` Joe Perches
2018-04-02 5:31 [PATCH 0/2] Move kfree_rcu out of rcu code and use kfree_bulk rao.shoaib
2018-04-02 5:31 ` [PATCH 1/2] Move kfree_call_rcu() to slab_common.c rao.shoaib
2018-04-02 7:59 ` kbuild test robot
2018-04-02 9:45 ` kbuild test robot
2018-04-02 15:43 ` Paul E. McKenney
2018-04-03 17:22 [PATCH 0/2] Move kfree_rcu out of rcu code and use kfree_bulk rao.shoaib
2018-04-03 17:22 ` [PATCH 1/2] Move kfree_call_rcu() to slab_common.c rao.shoaib
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