Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 29 Nov 2010 14:47:53 -0800 | From | Greg KH <> | Subject | Re: [PATCH 1/2] TTY: ldisc, fix open flag handling |
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On Mon, Nov 29, 2010 at 11:41:45PM +0100, Jiri Slaby wrote: > On 11/29/2010 10:50 PM, Greg KH wrote: > > On Thu, Nov 25, 2010 at 12:27:54AM +0100, Jiri Slaby wrote: > >> When a concrete ldisc open fails in tty_ldisc_open, we forget to clear > >> TTY_LDISC_OPEN. This causes a false warning on the next ldisc open: > >> WARNING: at drivers/char/tty_ldisc.c:445 tty_ldisc_open+0x26/0x38() > >> Hardware name: System Product Name > >> Modules linked in: ... > >> Pid: 5251, comm: a.out Tainted: G W 2.6.32-5-686 #1 > >> Call Trace: > >> [<c1030321>] ? warn_slowpath_common+0x5e/0x8a > >> [<c1030357>] ? warn_slowpath_null+0xa/0xc > >> [<c119311c>] ? tty_ldisc_open+0x26/0x38 > >> [<c11936c5>] ? tty_set_ldisc+0x218/0x304 > >> ... > >> > >> So clear the bit when failing... > >> > >> Introduced in c65c9bc3efa (tty: rewrite the ldisc locking) back in > >> 2.6.31-rc1. > >> > >> Signed-off-by: Jiri Slaby <jslaby@suse.cz> > >> Cc: Alan Cox <alan@linux.intel.com> > >> Reported-by: Sergey Lapin <slapin@ossfans.org> > >> Tested-by: Sergey Lapin <slapin@ossfans.org> > > > > Is this still needed, or can I just use your: > > [PATCH v2 1/2] TTY: don't allow reopen when ldisc is changing > > patch instead? > > This patch is still needed, it fixes a fail path.
Ok, thanks.
> Other than that there are 3 races in 2.6.36, one of them is introduced > in 2.6.36, the rest in 2.6.32. For each bug there is a single patch I sent: > * TTY: open/hangup race fixup > - introduced in 2.6.36 > - open vs hangup race > * TTY: don't allow reopen when ldisc is changing > - tiocsetd vs open race > * TTY: ldisc, fix open flag handling > - this you are asking about > - when ldisc->open fails, we blow up
Good, I have these three ready to go to Linus now.
> * Char: TTY, restore tty_ldisc_wait_idle > - this is in 37-rc2 already > - multiple opens followed by tiocsetd blows the machine up > > All of them are stable candidates (but I would give them some time in > HEAD to see if something breaks, since I opened a can of worms). The > first one is applicable only to 2.6.36 indeed.
Thanks for the details, much appreciated, as are your patches :)
greg k-h
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