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Date:   Fri, 9 Jun 2023 12:46:27 -0500
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Subject: Re: [PATCH v13 23/24] virt: gunyah: Add ioeventfd
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To:     Elliot Berman <quic_eberman@quicinc.com>,
        Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>,
        Jonathan Corbet <corbet@lwn.net>
Cc:     Murali Nalajala <quic_mnalajal@quicinc.com>,
        Trilok Soni <quic_tsoni@quicinc.com>,
        Srivatsa Vaddagiri <quic_svaddagi@quicinc.com>,
        Carl van Schaik <quic_cvanscha@quicinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Bagas Sanjaya <bagasdotme@gmail.com>,
        Will Deacon <will@kernel.org>, Andy Gross <agross@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Jassi Brar <jassisinghbrar@gmail.com>,
        linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
References: <20230509204801.2824351-1-quic_eberman@quicinc.com>
 <20230509204801.2824351-24-quic_eberman@quicinc.com>
 <85e7c3ae-0991-0ca9-909c-f38773f63894@linaro.org>
 <2f60fc9f-a8b2-fe8c-183a-5ee9b276b02d@quicinc.com>
From:   Alex Elder <elder@linaro.org>
In-Reply-To: <2f60fc9f-a8b2-fe8c-183a-5ee9b276b02d@quicinc.com>
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On 6/9/23 12:33 PM, Elliot Berman wrote:
>>> +static int gh_write_ioeventfd(struct gh_vm_io_handler *io_dev, u64 
>>> addr, u32 len, u64 data)
>>> +{
>>> +    struct gh_ioeventfd *iofd = container_of(io_dev, struct 
>>> gh_ioeventfd, io_handler);
>>
>> Does a write of 0 bytes still signal an event?
>>
> 
>  From gunyah_ioeventfd perspective, yes. I don't think a write of 0 
> bytes is possible, but maybe you are thinking of scenario I'm not?
> 
>>> +
>>> +    eventfd_signal(iofd->ctx, 1);
>>> +    return 0;
>>> +} 

No, I was just observing that eventfd_signal() is called regardless
of the value of len.

					-Alex