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Re: [Qemu-devel] [PATCH v2 52/52] usbaudio: change playback counters to
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [Qemu-devel] [PATCH v2 52/52] usbaudio: change playback counters to 64 bit |
Date: |
Tue, 25 Dec 2018 11:50:11 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 |
On 12/23/18 9:52 PM, Kővágó, Zoltán wrote:
> With stereo playback, they need about 375 minutes of continuous audio
> playback to overflow, which is usually not a problem (as stopping and
> later resuming playback resets the counters). But with 7.1 audio, they
> only need about 95 minutes to overflow.
>
> After the overflow, the buf->prod % USBAUDIO_PACKET_SIZE(channels)
> assertion no longer holds true, which will result in overflowing the
> buffer. With 64 bit variables, it would take about 762000 years to
> overflow.
>
> Signed-off-by: Kővágó, Zoltán <address@hidden>
> ---
> hw/usb/dev-audio.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/hw/usb/dev-audio.c b/hw/usb/dev-audio.c
> index 29475a2b70..45ffc3ebb3 100644
> --- a/hw/usb/dev-audio.c
> +++ b/hw/usb/dev-audio.c
> @@ -577,9 +577,9 @@ static const USBDesc desc_audio_multi = {
>
> struct streambuf {
> uint8_t *data;
> - uint32_t size;
> - uint32_t prod;
> - uint32_t cons;
> + size_t size;
> + uint64_t prod;
> + uint64_t cons;
OK.
> };
>
> static void streambuf_init(struct streambuf *buf, uint32_t size,
> @@ -600,12 +600,14 @@ static void streambuf_fini(struct streambuf *buf)
>
> static int streambuf_put(struct streambuf *buf, USBPacket *p, uint32_t
> channels)
> {
> - uint32_t free = buf->size - (buf->prod - buf->cons);
> + uint64_t free = buf->size - (buf->prod - buf->cons);
I'd use ssize_t here.
>
> if (free < USBAUDIO_PACKET_SIZE(channels)) {
> return 0;
> }
>
> + /* can happen if prod overflows */
> + assert(buf->prod % USBAUDIO_PACKET_SIZE(channels) == 0);
> usb_packet_copy(p, buf->data + (buf->prod % buf->size),
> USBAUDIO_PACKET_SIZE(channels));
> buf->prod += USBAUDIO_PACKET_SIZE(channels);
> @@ -614,7 +616,7 @@ static int streambuf_put(struct streambuf *buf, USBPacket
> *p, uint32_t channels)
>
> static uint8_t *streambuf_get(struct streambuf *buf, size_t *len)
> {
> - uint32_t used = buf->prod - buf->cons;
> + uint64_t used = buf->prod - buf->cons;
> uint8_t *data;
>
> if (!used) {
Eventually here:
ssize_t used = buf->prod - buf->cons;
if (used <= 0) {
return NULL;
}
- [Qemu-devel] [PATCH v2 38/52] audio: remove remains of the old backend api, (continued)
- [Qemu-devel] [PATCH v2 38/52] audio: remove remains of the old backend api, Kővágó, Zoltán, 2018/12/23
- [Qemu-devel] [PATCH v2 41/52] audio: common rate control code for timer based outputs, Kővágó, Zoltán, 2018/12/23
- [Qemu-devel] [PATCH v2 29/52] alsaaudio: port to the new audio backend api, Kővágó, Zoltán, 2018/12/23
- [Qemu-devel] [PATCH v2 34/52] paaudio: port to the new audio backend api, Kővágó, Zoltán, 2018/12/23
- [Qemu-devel] [PATCH v2 42/52] audio: split ctl_* functions into enable_* and volume_*, Kővágó, Zoltán, 2018/12/23
- [Qemu-devel] [PATCH v2 47/52] audio: replace shift in audio_pcm_info with bytes_per_frame, Kővágó, Zoltán, 2018/12/23
- [Qemu-devel] [PATCH v2 43/52] audio: add mixeng option (documentation), Kővágó, Zoltán, 2018/12/23
- [Qemu-devel] [PATCH v2 50/52] usb-audio: do not count on avail bytes actually available, Kővágó, Zoltán, 2018/12/23
- [Qemu-devel] [PATCH v2 49/52] paaudio: channel-map option, Kővágó, Zoltán, 2018/12/23
- [Qemu-devel] [PATCH v2 52/52] usbaudio: change playback counters to 64 bit, Kővágó, Zoltán, 2018/12/23
- Re: [Qemu-devel] [PATCH v2 52/52] usbaudio: change playback counters to 64 bit,
Philippe Mathieu-Daudé <=
- Re: [Qemu-devel] [PATCH v2 00/52] Audio 5.1 patches, Philippe Mathieu-Daudé, 2018/12/25
- Re: [Qemu-devel] [PATCH v2 00/52] Audio 5.1 patches, Programmingkid, 2018/12/26
- Re: [Qemu-devel] [PATCH v2 00/52] Audio 5.1 patches, Kővágó Zoltán, 2018/12/27
- Re: [Qemu-devel] [PATCH v2 00/52] Audio 5.1 patches, Programmingkid, 2018/12/27
- Re: [Qemu-devel] [PATCH v2 00/52] Audio 5.1 patches, Kővágó Zoltán, 2018/12/28
- Re: [Qemu-devel] [PATCH v2 00/52] Audio 5.1 patches, Programmingkid, 2018/12/28
- Re: [Qemu-devel] [PATCH v2 00/52] Audio 5.1 patches, Zoltán Kővágó, 2018/12/28
- Re: [Qemu-devel] [PATCH v2 00/52] Audio 5.1 patches, Programmingkid, 2018/12/28
- Re: [Qemu-devel] [PATCH v2 00/52] Audio 5.1 patches, Kővágó Zoltán, 2018/12/31