Re: [PATCH v3 2/3] eal: handle sysconf(_SC_PAGESIZE) negative return value

[Thomas Monjalon <thomas@monjalon.net>]

27/06/2025 19:49, Morten Brørup:
> > From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > Sent: Friday, 27 June 2025 19.35
> > 
> > 27/06/2025 18:38, Morten Brørup:
> > > > From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > > > Sent: Friday, 27 June 2025 17.58
> > > >
> > > > 24/06/2025 10:03, Morten Brørup:
> > > > > +		if ((ssize_t)page_size < 0)
> > > > > +			rte_panic("sysconf(_SC_PAGESIZE) failed: %s",
> > > > > +					errno == 0 ? "Indeterminate" :
> > > > strerror(errno));
> > > >
> > > > We don't want more rte_panic().
> > > > You could log the problem and return 0 here.
> > > > It will be a problem later, but it may allow the application to
> > cleanup
> > > > instead of abrupting crashing.
> > >
> > > Disagree.
> > > That would be likely to cause crash with division by zero later.
> > > Better to fail early.
> > 
> > Which division by zero?
> 
> Functions dividing by page size. E.g.:
> https://elixir.bootlin.com/dpdk/v25.03/source/lib/eal/common/eal_common_memory.c#L313
> 
> > 
> > I don't think a library should take this decision on behalf of the app.
> 
> I expect lots of things to break if sysconf(_SC_PAGESIZE) fails, so the purpose of this patch is to centralize error handling here, and only continue/return with non-failing values.
> 
> Otherwise, everywhere using rte_mem_page_size() or sysconf(_SC_PAGESIZE) should implement error handling (or ignore errors).
> That's a lot of places, so I'm not going to provide a patch doing that.

I understand.

The problem is that we don't have an exception mechanism in this language.