Re: [PATCH 0/9] Refactoring exit

Geert Uytterhoeven [off-list ref] writes:

Hi Michael,

On Mon, Jun 28, 2021 at 1:00 AM Michael Schmitz [off-list ref] wrote:

quoted

On 28/06/21 10:13 am, Al Viro wrote:

quoted

On Thu, Jun 24, 2021 at 10:45:23PM +0000, Al Viro wrote:

quoted

13) there's bdflush(1, whatever), which is equivalent to exit(0).
IMO it's long past the time to simply remove the sucker.

Incidentally, calling that from ptraced process on alpha leads to
the same headache for tracer.  _If_ we leave it around, this is
another candidate for "hit yourself with that special signal" -
both alpha and m68k have that syscall, and IMO adding an asm
wrapper for that one is over the top.

Said that, we really ought to bury that thing:

commit 2f268ee88abb33968501a44368db55c63adaad40
Author: Andrew Morton [off-list ref]
Date:   Sat Dec 14 03:16:29 2002 -0800

     [PATCH] deprecate use of bdflush()

     Patch from Robert Love [off-list ref]

     We can never get rid of it if we do not deprecate it - so do so and
     print a stern warning to those who still run bdflush daemons.

Deprecated for 18.5 years by now - I seriously suspect that we have
some contributors younger than that...

Haven't found that warning in over 7 years' worth of console logs, and
I'm a good candidate for running the oldest userland in existence for m68k.

Time to let it go.

The warning is printed when using filesys-ELF-2.0.x-1400K-2.gz,
which is a very old ramdisk from right after the m68k a.out to ELF
transition:

    warning: process `update' used the obsolete bdflush system call
    Fix your initscripts?

I still boot it, once in a while.

The only thing left in bdflush is func == 1 calls do_exit(0);

Which is a hack introduced in 2.3.23 aka October of 1999 to force the
userspace process calling bdflush to exit, instead of repeatedly calling
sys_bdflush.

Can you try deleting that func == 1 call and seeing if your old ramdisk
works?

I suspect userspace used to get into a tight spin calling bdflush
func == 1, when that function stopped doing anything.  That was back in
1999 so we are probably safe with out it.

Eric