Re: [Qemu-devel] [PATCH v3 05/46] ivshmem: factor out the incoming fifo handling

[Marc-André Lureau]

Hi

On Tue, Sep 22, 2015 at 4:01 PM, Claudio Fontana
<address@hidden> wrote:
> On 15.09.2015 18:07, address@hidden wrote:
>> From: Marc-André Lureau <address@hidden>
>>
>> Make a new function fifo_update_and_get() that can be reused by other
>> functions (in next commits).
>>
>> Signed-off-by: Marc-André Lureau <address@hidden>
>> ---
>>  hw/misc/ivshmem.c | 59 
>> ++++++++++++++++++++++++++++++++++++-------------------
>>  1 file changed, 39 insertions(+), 20 deletions(-)
>>
>> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
>> index 2162d02..dd15f0e 100644
>> --- a/hw/misc/ivshmem.c
>> +++ b/hw/misc/ivshmem.c
>> @@ -441,6 +441,42 @@ static int increase_dynamic_storage(IVShmemState *s, 
>> int new_min_size)
>>      return 0;
>>  }
>>
>> +static bool fifo_update_and_get(IVShmemState *s, const uint8_t *buf, int 
>> size,
>> +                                void *data, size_t len)
>> +{
>> +    const uint8_t *p;
>> +    uint32_t num;
>> +
>> +    assert(len <= sizeof(long)); /* limitation of the fifo */
>> +    if (fifo8_is_empty(&s->incoming_fifo) && size == len) {
>> +        memcpy(data, buf, size);
>> +        return true;
>> +    }
>> +
>> +    IVSHMEM_DPRINTF("short read of %d bytes\n", size);
>> +
>> +    num = MIN(size, sizeof(long) - fifo8_num_used(&s->incoming_fifo));
>> +    fifo8_push_all(&s->incoming_fifo, buf, num);
>> +
>> +    if (fifo8_num_used(&s->incoming_fifo) < len) {
>> +        assert(num == 0);
>> +        return false;
>> +    }
>> +
>> +    size -= num;
>> +    buf += num;
>> +    p = fifo8_pop_buf(&s->incoming_fifo, len, &num);
>> +    assert(num == len);
>> +
>> +    memcpy(data, p, len);
>> +
>> +    if (size > 0) {
>> +        fifo8_push_all(&s->incoming_fifo, buf, size);
>> +    }
>> +
>> +    return true;
>> +}
>> +
>>  static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
>>  {
>>      IVShmemState *s = opaque;
>> @@ -448,26 +484,9 @@ static void ivshmem_read(void *opaque, const uint8_t 
>> *buf, int size)
>>      int guest_max_eventfd;
>>      long incoming_posn;
>>
>> -    if (fifo8_is_empty(&s->incoming_fifo) && size == sizeof(incoming_posn)) 
>> {
>> -        memcpy(&incoming_posn, buf, size);
>> -    } else {
>> -        const uint8_t *p;
>> -        uint32_t num;
>> -
>> -        IVSHMEM_DPRINTF("short read of %d bytes\n", size);
>> -        num = MIN(size, sizeof(long) - fifo8_num_used(&s->incoming_fifo));
>> -        fifo8_push_all(&s->incoming_fifo, buf, num);
>> -        if (fifo8_num_used(&s->incoming_fifo) < sizeof(incoming_posn)) {
>> -            return;
>> -        }
>> -        size -= num;
>> -        buf += num;
>> -        p = fifo8_pop_buf(&s->incoming_fifo, sizeof(incoming_posn), &num);
>> -        g_assert(num == sizeof(incoming_posn));
>> -        memcpy(&incoming_posn, p, sizeof(incoming_posn));
>> -        if (size > 0) {
>> -            fifo8_push_all(&s->incoming_fifo, buf, size);
>> -        }
>> +    if (!fifo_update_and_get(s, buf, size,
>> +                             &incoming_posn, sizeof(incoming_posn))) {
>> +        return;
>>      }
>>
>>      if (incoming_posn < -1) {
>>
>
>
> Fine in principle, I have that reservation about using sizeof(long) as part 
> of the interface.


This will be treated in a seperate patch.

-- 
Marc-André Lureau