Re: [Dazuko-devel] Patch 2/5

[Lino Sanfilippo]

John Ogness wrote:
> On 2010-07-08, Lino Sanfilippo <address@hidden> wrote:
>   
> > This patch enables behaviour compatible with BSD signal semantics by
> > making the read() calls on the dazukofs devices restartable across
> > signals.
> >     
>
> It is not clear to me that this is proper behavior for read() return
> values. I have decided not to apply this patch for 3.1.4-rc1.
>
> John Ogness
>   
Hi,

Userspace will (in most cases) still see -EINTR if interrupted by a 
signal (in fact
-ERESTARTSYS should never be seen by userspace).
The exception is if a signal handler has been installed with the 
SA_RESTART flag
set, the kernel will try to restart the interrupted system call (read() 
from dazukofs
device in our case) and not notify userspace.
This is a feature that has been introduced by BSD and is also supported 
by Linux.
I thought it would be nice if dazukofs would support those semantics, 
too (i know
some device drivers do, but I dont think its something a device _has_ to 
support...)

Regards,
Lino


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