Messages in this thread | | | Date | Tue, 19 Aug 2008 19:56:39 +0200 | From | Ico Doornekamp <> | Subject | Re: TIOCGWINSZ retuns old pty size after receiving SIGWINCH |
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* On 2008-08-19 Ico Doornekamp <lkml@zevv.nl> wrote :
> > > * On 2008-08-19 Andrew Morton <akpm@linux-foundation.org> wrote : > > > On Tue, 19 Aug 2008 09:54:14 +0200 Ico Doornekamp <lkml@zevv.nl> wrote: > > > > > > * On 2008-08-19 Andrew Morton <akpm@linux-foundation.org> wrote : > > > > > > > On Sun, 10 Aug 2008 17:08:59 +0200 Ico Doornekamp <lkml@zevv.nl> wrote: > > > > > > > > > Recently my X terminals showed annoying behaviour where the application > > > > > in the terminal was not resized properly to the actual size of the X > > > > > terminal emulator window, resulting in a lot of misaligned text on the > > > > > screen. Hunting the issue down from the windowmanager and the terminal > > > > > emulator program, I suspect the problem might lie in the kernel. I'm > > > > > running 2.6.26 on a dual core i386. > > > > > > > > > > What I see is this: the userspace application receives a SIGWINCH signal > > > > > and acquires the terminal size usign the TIOCGWINSZ ioctl. It seems that > > > > > in some cases the old instead of the new terminal size is returned. > > > > > A small delay before the ioctl seems to 'fix' this behaviour. > > > > > > > > > > I noticed some changes involving locking in the the pty code in the last > > > > > kernel verions, could one of these changes cause the above behaviour ? If > > > > > so, wouldn't this affect much more users ? > > > > > > > > hm, that code is pretty simple and although it does the SIGWINCH and > > > > the window-size setting in a peculiar order, it looks to be race-free. > > > > > > > > Approximately what proportion of the time does it go wrong? > > > > > > I guess about 10 to 20% of the resizes. I happen to be using a tiling > > > window manager which causes resizing more often and more agressive then > > > 'normal' window managers, I guess this helps triggering the problem. > > > > > > I temporary worked around this issue this by changing the order of the > > > signal and the updating of the pty size in tty_io.c's tiocswinsz(), but > > > this is not much of a real fix. > > > > > > > Well damn. Are you sure? The code looks solid to me. > > > > At least, it does after > > > > Author: Alan Cox <alan@redhat.com> 2008-08-15 02:39:38 > > Committer: Linus Torvalds <torvalds@linux-foundation.org> 2008-08-15 10:34:07 > > Parent: 000b9151d7851cc1e490b2a76d0206e524f43cca (Fix race/oops in tty layer after BKL pushdown) > > Branches: git-cifs, git-ia64, git-nfs, git-powerpc-merge, linux-next, remotes/origin/master > > Follows: v2.6.27-rc3 > > Precedes: next-20080818 > > > > tty: remove resize window special case > > > > perhaps you're still running a kernel which is earlier than that? > > I reported the behaviour on 2.6.26.2, but I was not aware this issue was > adressed already in the 2.6.27 tree. I will update to the latest 2.6.27 > rc and report if the problem still persists.
I am not able to reproduce the problem with git 2.6.27-rc3-next-20080819.
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