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Re: [Qemu-devel] [Qemu-block] [PATCH 01/17] block: access copy_on_read w
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [Qemu-block] [PATCH 01/17] block: access copy_on_read with atomic ops |
Date: |
Thu, 4 May 2017 12:15:36 +0100 |
User-agent: |
Mutt/1.8.0 (2017-02-23) |
On Thu, Apr 20, 2017 at 02:00:42PM +0200, Paolo Bonzini wrote:
> void bdrv_disable_copy_on_read(BlockDriverState *bs)
> {
> - assert(bs->copy_on_read > 0);
> - bs->copy_on_read--;
> + assert(atomic_read(&bs->copy_on_read) > 0);
> + atomic_dec(&bs->copy_on_read);
> }
To make this truly thread-safe:
old = atomic_dec_fetch(&bs->copy_on_read);
assert(old > 0);
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- Re: [Qemu-devel] [Qemu-block] [PATCH 01/17] block: access copy_on_read with atomic ops,
Stefan Hajnoczi <=