Re: [Xen-devel] [PATCH v2 1/3] xen: fix usage of ENODATA

[Roger Pau Monnà <roger.pau@xxxxxxxxxx>]

On 27/05/14 18:18, Stefano Stabellini wrote:
> On Fri, 23 May 2014, Roger Pau Monne wrote:
>> ENODATA doesn't exist on FreeBSD, so ENODATA errors returned by the
>> hypervisor are translated to ENOENT.
>>
>> Also, the error code is returned in errno if the call returns -1, so
>> compare the error code with the value in errno instead of the value
>> returned by the function.
>>
>> Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
>> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
>> Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>> Cc: Anthony Perard <anthony.perard@xxxxxxxxxx>
>> ---
>> Changes since v1:
>>  - Define ENODATA to ENOENT for platforms that don't have ENODATA.
>> ---
>>  xen-hvm.c |    7 +++++--
>>  1 files changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/xen-hvm.c b/xen-hvm.c
>> index a64486c..a414105 100644
>> --- a/xen-hvm.c
>> +++ b/xen-hvm.c
>> @@ -499,11 +499,14 @@ static void xen_sync_dirty_bitmap(XenIOState *state,
>>                                   start_addr >> TARGET_PAGE_BITS, npages,
>>                                   bitmap);
>>      if (rc < 0) {
>> -        if (rc != -ENODATA) {
>> +#ifndef ENODATA
>> +#define ENODATA  ENOENT
>> +#endif
> 
> I wonder if it makes sense to have this in a more generic header, lile
> include/qemu/osdep.h?

Well, I think this is something really specific to Xen, because FreeBSD
is mapping the error returned by Xen (ENODATA), to a error code
available on FreeBSD (ENOENT), see:

http://xenbits.xen.org/gitweb/?p=people/royger/freebsd.git;a=patch;h=f09eeed01bc884b37e978f6ec6e3e7a86778ef4b

But I don't think this is useful outside of this context, since there's
no syscall that would return ENODATA on FreeBSD that instead returns
ENOENT. All the paths in Qemu that check for ENODATA are Linux specific
AFAICT.

Roger.

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