Re: [PATCH] Make EWOULDBLOCK be equal to EAGAIN on parisc.

[Mike Frysinger <vapier@gentoo.org>]

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On Friday, January 31, 2014 12:24:10 Carlos O'Donell wrote:
> On Fri, Jan 31, 2014 at 11:53 AM, Helge Deller <deller@gmx.de> wrote:
> > On 01/16/2014 05:17 PM, Guy Martin wrote:
> >> On Linux, only parisc uses a different value for EWOULDBLOCK which
> >> causes a lot of troubles for applications not checking for both values.
> >> Since the hpux compat is long dead, make EWOULDBLOCK behave the same as
> >> all other architectures.
> >> 
> >> Signed-off-by: Guy Martin  <gmsoft@tuxicoman.be>
> > 
> > What's our final decision regarding this patch now?
> > Shall we target it for inclusion into 3.14 ?
> > If yes, I can include it with my next push request...
> > 
> > Please speak up now...!
> > 
> > Helge
> > 
> >> ---
> >> 
> >>  arch/parisc/include/uapi/asm/errno.h | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >> 
> >> diff --git a/arch/parisc/include/uapi/asm/errno.h
> >> b/arch/parisc/include/uapi/asm/errno.h index f3a8aa5..c0ae625 100644
> >> --- a/arch/parisc/include/uapi/asm/errno.h
> >> +++ b/arch/parisc/include/uapi/asm/errno.h
> >> @@ -106,7 +106,7 @@
> >> 
> >>  #define    EALREADY    244    /* Operation already in progress */
> >>  #define    EINPROGRESS    245    /* Operation now in progress */
> >> 
> >> -#define    EWOULDBLOCK    246    /* Operation would block (Linux returns
> >> EAGAIN) */ +#define    EWOULDBLOCK    EAGAIN    /* Operation would block
> >> (Not HPUX compliant) */>> 
> >>  #define    ENOTEMPTY    247    /* Directory not empty */
> >>  #define    ENAMETOOLONG    248    /* File name too long */
> >>  #define    ELOOP        249    /* Too many symbolic links encountered */
> 
> I think we should do it and fix the userspace fallout by rebuilding.

i'm not sure userspace will break ?  we've got two classes of code:
 - stuff that checks both EAGAIN & EWOULDBLOCK and treats them the same
 - stuff that checks EAGAIN only (and probably should check both, but doesn't)
both of those will continue to work after we change EWOULDBLOCK

i don't think there's really any code out there that only looks at EWOULDBLOCK 
(or does so differently from EAGAIN).  if there is, then they'd break.  but if 
they never sh*t in the woods in the first place, then who cares if they would 
have made noise ? :)
-mike

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