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Re: [Qemu-devel] [PATCH v2 3/4] exec: Notify cpu_register_map_client cal
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v2 3/4] exec: Notify cpu_register_map_client caller if the bounce buffer is available |
Date: |
Fri, 13 Mar 2015 09:12:25 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
On 13/03/2015 02:38, Fam Zheng wrote:
> The caller's workflow is like
>
> if (!address_space_map()) {
> ...
> cpu_register_map_client();
> }
>
> If bounce buffer became available after address_space_map() but before
> cpu_register_map_client(), the caller could miss it and has to wait for the
> next bounce buffer uesr to release, which may never happen in the worse case.
>
> Just notify the caller with the passed callback in cpu_register_map_client().
>
> Signed-off-by: Fam Zheng <address@hidden>
> ---
> exec.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/exec.c b/exec.c
> index 93ccd5a..82781e4 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -2502,6 +2502,9 @@ void *cpu_register_map_client(void *opaque, void
> (*callback)(void *opaque))
> client->opaque = opaque;
> client->callback = callback;
> QSLIST_INSERT_HEAD_ATOMIC(&map_client_list, client, link);
> + if (!atomic_read(&bounce.in_use)) {
> + callback(opaque);
This should call cpu_notify_map_clients instead, otherwise you get two
calls.
Paolo
> + }
> return client;
> }
>
>
- Re: [Qemu-devel] [PATCH v2 4/4] dma-helpers: Move reschedule_dma BH to blk's AioContext, (continued)
[Qemu-devel] [PATCH v2 2/4] exec: Atomic access to map_client_list, Fam Zheng, 2015/03/12
[Qemu-devel] [PATCH v2 3/4] exec: Notify cpu_register_map_client caller if the bounce buffer is available, Fam Zheng, 2015/03/12
- Re: [Qemu-devel] [PATCH v2 3/4] exec: Notify cpu_register_map_client caller if the bounce buffer is available,
Paolo Bonzini <=