[Qemu-devel] Re: [PATCH v7 3/6] char: Let writers know how much data was written in case of errors

[Amit Shah <amit.shah@redhat.com>]

On (Wed) May 05 2010 [08:54:48], Anthony Liguori wrote:
> On 05/05/2010 08:23 AM, Amit Shah wrote:
>> On (Wed) May 05 2010 [08:15:19], Anthony Liguori wrote:
>>    
>>> On 05/04/2010 04:39 PM, Amit Shah wrote:
>>>      
>>>> On writing errors, we just returned -1 even if some bytes were already
>>>> written out. Ensure we return the number of bytes written before we
>>>> return the error (on a subsequent call to qemu_chr_write()).
>>>>
>>>> Signed-off-by: Amit Shah<amit.shah@redhat.com>
>>>> ---
>>>>    qemu-char.c |   12 +++++++++++-
>>>>    1 files changed, 11 insertions(+), 1 deletions(-)
>>>>
>>>> diff --git a/qemu-char.c b/qemu-char.c
>>>> index 76ad12c..decf687 100644
>>>> --- a/qemu-char.c
>>>> +++ b/qemu-char.c
>>>> @@ -507,6 +507,9 @@ int send_all(int fd, const void *buf, int len1)
>>>>        while (len>   0) {
>>>>            ret = send(fd, buf, len, 0);
>>>>            if (ret<   0) {
>>>> +            if (len1 - len) {
>>>> +                return len1 - len;
>>>> +            }
>>>>                errno = WSAGetLastError();
>>>>                if (errno != WSAEWOULDBLOCK) {
>>>>                    return -1;
>>>> @@ -531,8 +534,15 @@ static int unix_write(int fd, const uint8_t *buf, int len1)
>>>>        while (len>   0) {
>>>>            ret = write(fd, buf, len);
>>>>            if (ret<   0) {
>>>> -            if (errno != EINTR&&   errno != EAGAIN)
>>>> +            if (errno == EINTR) {
>>>> +                continue;
>>>> +            }
>>>> +            if (len1 - len) {
>>>> +                return len1 - len;
>>>> +            }
>>>> +            if (errno != EAGAIN) {
>>>>                    return -1;
>>>> +            }
>>>>            } else if (ret == 0) {
>>>>                break;
>>>>            } else {
>>>>
>>>>        
>>> This will break lots of things.  The contract for send_all and
>>> unix_write is that the transmit all data.
>>>      
>> The current behaviour remains unchanged for all the users. Only callers
>> of qemu_chr_write_nb() will get an -EAGAIN return.
>>    
>
> No, send_all used to send all data.  After your change, it only sends  
> what it can the first time.  The same with unix_write.

Where do you see this?

		Amit