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Re: [v2] locking/percpu-rwsem: Optimize readers and reduce global impact

From Guenter Roeck <linux@roeck-us.net>
Newsgroups linux.kernel
Subject Re: [v2] locking/percpu-rwsem: Optimize readers and reduce global impact
Date 2016-08-31 15:50 +0200
Message-ID <sce3U-31q-3@gated-at.bofh.it> (permalink)
References <s4bZf-5Sz-15@gated-at.bofh.it> <sc6g1-6Gh-5@gated-at.bofh.it> <sc8Ux-8n3-7@gated-at.bofh.it> <sce3U-31q-5@gated-at.bofh.it>
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On 08/31/2016 06:41 AM, Guenter Roeck wrote:
> On 08/31/2016 01:09 AM, Peter Zijlstra wrote:
>> On Tue, Aug 30, 2016 at 10:21:02PM -0700, Guenter Roeck wrote:
>>> Peter,
>>>
>>> The call to rcu_sync_is_idle() causes the following build error when building
>>> x86_64:allmodconfig.
>>>
>>> ERROR: "rcu_sync_lockdep_assert" [kernel/locking/locktorture.ko] undefined!
>>> ERROR: "rcu_sync_lockdep_assert" [fs/ext4/ext4.ko] undefined!
>>>
>>> I think this was also reported by the 0-day build bot.
>>>
>>> The simple fix would of course be to export rcu_sync_lockdep_assert. Before I
>>> apply that change to the Android code (where the patch has been aplied and
>>> the problem is seen) - do you by any chance have a better solution in mind ?
>>
>> Nope, that's exactly what Ingo did when he ran into this. If you look at
>> commit 80127a39681b ("locking/percpu-rwsem: Optimize readers and reduce
>> global impact"), you'll notice the last hunk:
>>
> Ah, I missed that, and didn't realize that it is already upstream. Thanks a lot!
>

Wait, it isn't ... I must have fetched a branch with 80127a39681b. Ignore the noise
I am making until after I had another coffee.

Guenter

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Thread

Re: [v2] locking/percpu-rwsem: Optimize readers and reduce global  impact Guenter Roeck <linux@roeck-us.net> - 2016-08-31 07:30 +0200
  Re: [v2] locking/percpu-rwsem: Optimize readers and reduce global  impact Peter Zijlstra <peterz@infradead.org> - 2016-08-31 10:20 +0200
    Re: [v2] locking/percpu-rwsem: Optimize readers and reduce global  impact Guenter Roeck <linux@roeck-us.net> - 2016-08-31 15:50 +0200
    Re: [v2] locking/percpu-rwsem: Optimize readers and reduce global  impact Guenter Roeck <linux@roeck-us.net> - 2016-08-31 15:50 +0200

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