From: Paolo Bonzini <pbonzini@redhat.com>
To: Fam Zheng <famz@redhat.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v2 1/4] exec: Atomic access to bounce buffer
Date: Fri, 13 Mar 2015 09:32:06 +0100 [thread overview]
Message-ID: <5502A086.5030208@redhat.com> (raw)
In-Reply-To: <20150313081603.GB18156@ad.nay.redhat.com>
On 13/03/2015 09:16, Fam Zheng wrote:
>>> > > + if (atomic_cmpxchg(&bounce.in_use, false, true)) {
>> >
>> > atomic_or is enough...
> atomic_cmpxchg is here to take the ownership of bounce iff it is not in use, so
> I think it is necessary.
It's changing false to true and true to true, so you can do
if (atomic_or(&bounce.in_use, 1)) {
// was true already
}
Paolo
next prev parent reply other threads:[~2015-03-13 8:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-13 1:38 [Qemu-devel] [PATCH v2 0/4] exec: Make bounce buffer thread safe Fam Zheng
2015-03-13 1:38 ` [Qemu-devel] [PATCH v2 1/4] exec: Atomic access to bounce buffer Fam Zheng
2015-03-13 8:09 ` Paolo Bonzini
2015-03-13 8:16 ` Fam Zheng
2015-03-13 8:32 ` Paolo Bonzini [this message]
2015-03-13 8:38 ` Fam Zheng
2015-03-13 8:41 ` Paolo Bonzini
2015-03-13 1:38 ` [Qemu-devel] [PATCH v2 2/4] exec: Atomic access to map_client_list Fam Zheng
2015-03-13 8:11 ` Paolo Bonzini
2015-03-13 1:38 ` [Qemu-devel] [PATCH v2 3/4] exec: Notify cpu_register_map_client caller if the bounce buffer is available Fam Zheng
2015-03-13 8:12 ` Paolo Bonzini
2015-03-13 1:38 ` [Qemu-devel] [PATCH v2 4/4] dma-helpers: Move reschedule_dma BH to blk's AioContext Fam Zheng
2015-03-13 8:13 ` Paolo Bonzini
2015-03-13 8:58 ` Fam Zheng
2015-03-13 10:48 ` Paolo Bonzini
2015-03-13 12:33 ` Paolo Bonzini
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