Re: [Qemu-devel] [PATCH] hw/block/fdc: floppy command FIFO memory initialization

[Andrey Shinkevich]

On 29/05/2019 16:40, John Snow wrote:
> 
> 
> On 5/29/19 8:22 AM, Andrey Shinkevich wrote:
>> The uninitialized memory allocated for the command FIFO of the
>> floppy controller during the VM hardware initialization incurs
>> many unwanted reports by Valgrind when VM state is being saved.
>> That verbosity hardens a search for the real memory issues when
>> the iotests run. Particularly, the patch eliminates 20 unnecessary
>> reports of the Valgrind tool in the iotest #169.
>>
>> Signed-off-by: Andrey Shinkevich <address@hidden>
>> ---
>>   hw/block/fdc.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/hw/block/fdc.c b/hw/block/fdc.c
>> index 6f19f12..54e470c 100644
>> --- a/hw/block/fdc.c
>> +++ b/hw/block/fdc.c
>> @@ -2647,6 +2647,10 @@ static void fdctrl_realize_common(DeviceState *dev, 
>> FDCtrl *fdctrl,
>>   
>>       FLOPPY_DPRINTF("init controller\n");
>>       fdctrl->fifo = qemu_memalign(512, FD_SECTOR_LEN);
>> +    if (fdctrl->fifo) {
>> +        /* To avoid using the uninitialized memory while saving VM state */
>> +        memset(fdctrl->fifo, 0, FD_SECTOR_LEN);
>> +    }
> 
> qemu_memalign doesn't look like it can fail (looking at
> util/oslib-posix); is this conditional necessary?
> 
> I think you could just:
> 
> fdctrl->fifo = qemu_memalign(512, FD_SECTOR_LEN);
> memset(fdctrl->fifo, 0, FD_SECTOR_LEN);
> 
>>       fdctrl->fifo_size = 512;
>>       fdctrl->result_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
>>                                                fdctrl_result_timer, fdctrl);
>>

Yes, that's right.
Thank you, John.

Andrey