Re: [PATCH] Linux-2.5 fix/improve get_pid()

From: Andrew Morton (akpm@zip.com.au)
Date: Fri Aug 09 2002 - 04:35:50 EST


Alan Cox wrote:
>
> On Fri, 2002-08-09 at 09:48, Helge Hafting wrote:
> > Use 32-bit PID's, but with an additional rule for wraparound.
> > Simply wrap the PID when
> > (nextPID > 2*number_of_processes && nextPID > 30000)
> > The latter one just to avoid wrapping at 10 when there are
> > 5 processes.
>
> Its much simpler to put max_pid into /proc/sys/kernel. That way we can
> boot with 32000 process ids, which will ensure ancient stuff which has
> 16bit pid_t (old old libc) and also any old kernel interfaces which
> expose it - does ipc ?

procfs oopses with >65535 processes, btw. Related to the i_ino
encoding:

        #define fake_ino(pid,ino) (((pid)<<16)|(ino))
        #define PROC_INODE_PROPER(inode) ((inode)->i_ino & ~0xffff)

it ruined Anton's evening ;)
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