From: Dexuan Cui <decui@microsoft.com>
To: KY Srinivasan <kys@microsoft.com>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "devel@linuxdriverproject.org" <devel@linuxdriverproject.org>,
        "olaf@aepfle.de" <olaf@aepfle.de>,
        "apw@canonical.com" <apw@canonical.com>,
        "vkuznets@redhat.com" <vkuznets@redhat.com>,
        "jasowang@redhat.com" <jasowang@redhat.com>
CC: Chris Oo <t-chriso@microsoft.com>
Subject: RE: [PATCH 3/5] Drivers: hv_vmbus: Fix signal to host condition
Thread-Topic: [PATCH 3/5] Drivers: hv_vmbus: Fix signal to host condition
Thread-Index: AQHQwpGpnJL6/oHUdkWi03YQwrDeuZ3kNCCA
Date: Mon, 20 Jul 2015 11:33:30 +0000
Message-ID: <ddb01ba986f14caeb28f40d40c99285b@SIXPR30MB031.064d.mgd.msft.net>
References: <1437363419-3511-1-git-send-email-kys@microsoft.com>
 <1437363447-3554-1-git-send-email-kys@microsoft.com>
 <1437363447-3554-3-git-send-email-kys@microsoft.com>
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> -----Original Message-----
> From: deve On Behalf of K. Y. Srinivasan
> Sent: Monday, July 20, 2015 11:37
> 
> From: Christopher Oo
> 
> Fixes a bug where previously hv_ringbuffer_read would pass in the old
> number of bytes available to read instead of the expected old read index
> when calculating when to signal to the host that the ringbuffer is empty.
> Since the previous write size is already saved, also changes the
> hv_need_to_signal_on_read to use the previously read value rather than
> recalculating it.
> 
> diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
> @@ -560,7 +552,7 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info
> *inring_info, void *buffer,
> 
>  	spin_unlock_irqrestore(&inring_info->ring_lock, flags);
> 
> -	*signal = hv_need_to_signal_on_read(old_read, inring_info);
> +	*signal = hv_need_to_signal_on_read(bytes_avail_towrite, inring_info);
> 
>  	return 0;
>  }

Good catch!

-- Dexuan
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