Re: [Qemu-devel] [PATCH 1/5] qemu-char: Add new char backend CircularMemCharDriver

[Lei Li <lilei@linux.vnet.ibm.com>]

On 10/23/2012 02:14 AM, Luiz Capitulino wrote:
> On Mon, 22 Oct 2012 00:47:57 +0800
> Lei Li <lilei@linux.vnet.ibm.com> wrote:
>
>> Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
> This patch should be squashed in the next one. More comments below.
>
>> ---
>>   qemu-char.c |   72 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   1 files changed, 72 insertions(+), 0 deletions(-)
>>
>> diff --git a/qemu-char.c b/qemu-char.c
>> index b082bae..b174da1 100644
>> --- a/qemu-char.c
>> +++ b/qemu-char.c
>> @@ -2588,6 +2588,78 @@ size_t qemu_chr_mem_osize(const CharDriverState *chr)
>>       return d->outbuf_size;
>>   }
>>   
>> +/*********************************************************/
>> +/*CircularMemoryr chardev*/
> s/Memoryr/Memory
>
>> +
>> +typedef struct {
>> +    size_t size;
>> +    size_t producer;
>> +    size_t consumer;
>> +    uint8_t *cbuf;
>> +} CirMemCharDriver;
>> +
>> +static bool cirmem_chr_is_empty(const CharDriverState *chr)
>> +{
>> +    const CirMemCharDriver *d = chr->opaque;
>> +
>> +    return d->producer == d->consumer;
>> +}
>> +
>> +static bool cirmem_chr_is_full(const CharDriverState *chr)
>> +{
>> +    const CirMemCharDriver *d = chr->opaque;
>> +
>> +    return (d->producer - d->consumer) >= d->size;
>> +}
>> +
>> +static int cirmem_chr_write(CharDriverState *chr, const uint8_t *buf, int len)
>> +{
>> +    CirMemCharDriver *d = chr->opaque;
>> +    int i;
>> +
>> +    if (len < 0) {
>> +        return -1;
>> +    }
>> +
>> +    /* The size should be a power of 2. */
>> +    for (i = 0; i < len; i++ ) {
>> +        d->cbuf[d->producer % d->size] = buf[i];
>> +        d->producer++;
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static int cirmem_chr_read(CharDriverState *chr, uint8_t *buf, int len)
>> +{
>> +    CirMemCharDriver *d = chr->opaque;
>> +    int i;
>> +
>> +    if (cirmem_chr_is_empty(chr) || len < 0) {
>> +        return -1;
>> +    }
>> +
>> +    if (len > d->size) {
>> +        len = d->size;
>> +    }
>> +
>> +    for (i = 0; i < len; i++) {
>> +        buf[i] = d->cbuf[d->consumer % d->size];
>> +        d->consumer++;
>> +    }
>> +
>> +    return 0;
>> +}
> You don't seem to reset producer/consumer anywhere, I wonder if it's possible
> for a long running VM to trigger the limit here.

Yes, it make sense.


-- 
Lei