Messages in this thread | | | Date | Tue, 03 Jan 2012 02:21:46 +0400 | From | Konstantin Khlebnikov <> | Subject | Re: [PATCH 2/2] tty: rework pty count limiting |
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Greg KH wrote: > On Mon, Jan 02, 2012 at 09:23:01PM +0400, Konstantin Khlebnikov wrote: >> After adding devpts multiple-insrances sysctl kernel.pty.max limit pty count for >> each devpts instance independently, while kernel.pty.nr shows total pty count. >> >> This patch restores sysctl kernel.pty.max as global limit (4096 by default), >> adds pty reseve for main devpts (mounted without "newinstance" argument), >> and new sysctl to tune it: kernel.pty.reserve (1024 by default) >> >> Also it adds devpts mount option "max=%d" to limit pty count for each devpts >> instance independently. (by default NR_UNIX98_PTY_MAX == 2^20) >> >> Thus devpts instances in containers cannot eat up all available pty even if we didn't >> set any limits, while with "max" argument we can adjust limits more precisely. >> >> Plus, now open("/dev/ptmx") return -ENOSPC in case lack of pty indexes, >> this is more informative than -EIO. > > That's a userspace api change, why is this going to be allowed?
open() can return -ENOSPC in case normal fs, meanwhile error codes for /dev/ptmx wasn't documented at all: there is nothing in manpage pts, pty and ptmx. manpage posix_openpt and getpt refers to manpage open(2). I can return EIO back, if this is critical.
> > greg k-h
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