From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Julien Grall <julien.grall@arm.com>, xen-devel@lists.xen.org
Cc: sstabellini@kernel.org, wei.liu2@citrix.com,
George.Dunlap@eu.citrix.com, andrew.cooper3@citrix.com,
ian.jackson@eu.citrix.com, tim@xen.org, jbeulich@suse.com
Subject: Re: [PATCH v7 6/9] spinlock: Introduce spin_lock_cb()
Date: Mon, 14 Aug 2017 10:39:10 -0400 [thread overview]
Message-ID: <77fcdcda-b0fa-cdda-2fee-24eace93c011@oracle.com> (raw)
In-Reply-To: <766310e2-aabd-7b23-0bae-1cd8b74a5119@arm.com>
>>
>> +#define spin_lock_kick(l) \
>> +({ \to understand why
>> you need a stronger one here
>> + smp_mb(); \
>
> arch_lock_signal() has already a barrier for ARM. So we have a double
> barrier now.
>
> However, the barrier is slightly weaker (smp_wmb()). I am not sure why
> you need to use a stronger barrier here. What you care is the write to
> be done before signaling, read does not much matter. Did I miss anything?
Yes, smp_wmb() should be sufficient.
Should I then add arch_lock_signal_wmb() --- defined as
arch_lock_signal() for ARM and smp_wmb() for x86?
-boris
>
> Cheers,
>
>> + arch_lock_signal(); \
>> +})
>> +
>> /* Ensure a lock is quiescent between two critical operations. */
>> #define spin_barrier(l) _spin_barrier(l)
>>
>>
>
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next prev parent reply other threads:[~2017-08-14 14:39 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-08 21:44 [PATCH v7 0/9] Memory scrubbing from idle loop Boris Ostrovsky
2017-08-08 21:44 ` [PATCH v7 1/9] mm: Clean up free_heap_pages() Boris Ostrovsky
2017-08-10 12:21 ` Wei Liu
2017-08-14 10:30 ` Jan Beulich
2017-08-08 21:45 ` [PATCH v7 2/9] mm: Place unscrubbed pages at the end of pagelist Boris Ostrovsky
2017-08-14 10:37 ` Jan Beulich
2017-08-14 14:29 ` Boris Ostrovsky
2017-08-15 8:18 ` Jan Beulich
2017-08-15 14:41 ` Boris Ostrovsky
2017-08-15 14:51 ` Jan Beulich
2017-08-15 14:52 ` Julien Grall
2017-08-15 15:03 ` Boris Ostrovsky
2017-08-15 15:08 ` Jan Beulich
2017-08-14 11:16 ` Julien Grall
2017-08-08 21:45 ` [PATCH v7 3/9] mm: Extract allocation loop from alloc_heap_pages() Boris Ostrovsky
2017-08-08 21:45 ` [PATCH v7 4/9] mm: Scrub pages in alloc_heap_pages() if needed Boris Ostrovsky
2017-08-08 21:45 ` [PATCH v7 5/9] mm: Scrub memory from idle loop Boris Ostrovsky
2017-08-08 21:45 ` [PATCH v7 6/9] spinlock: Introduce spin_lock_cb() Boris Ostrovsky
2017-08-14 11:22 ` Julien Grall
2017-08-14 14:39 ` Boris Ostrovsky [this message]
2017-08-14 14:42 ` Julien Grall
2017-08-14 14:57 ` Boris Ostrovsky
2017-08-08 21:45 ` [PATCH v7 7/9] mm: Keep heap accessible to others while scrubbing Boris Ostrovsky
2017-08-14 10:38 ` Jan Beulich
2017-08-08 21:45 ` [PATCH v7 8/9] mm: Print number of unscrubbed pages in 'H' debug handler Boris Ostrovsky
2017-08-08 21:45 ` [PATCH v7 9/9] mm: Make sure pages are scrubbed Boris Ostrovsky
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