From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Date: Thu, 16 Oct 2014 19:12:47 +0000 Subject: Re: [PATCH] ia64: Pin controlling tty for unaligned fault message Message-Id: <544018AF.5090507@hurleysoftware.com> List-Id: References: <1413486653-26010-1-git-send-email-peter@hurleysoftware.com> In-Reply-To: <1413486653-26010-1-git-send-email-peter@hurleysoftware.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tony Luck , Fenghua Yu Cc: Greg Kroah-Hartman , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org On 10/16/2014 03:10 PM, Peter Hurley wrote: > Prevent destruction of the controlling tty before tty_write_message() > can determine if the tty is safe to use. This does not make tty_write_message() bulletproof from concurrent teardown, but that's on my todo list. > Signed-off-by: Peter Hurley > --- > arch/ia64/kernel/unaligned.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/arch/ia64/kernel/unaligned.c b/arch/ia64/kernel/unaligned.c > index 622772b..e7ae608 100644 > --- a/arch/ia64/kernel/unaligned.c > +++ b/arch/ia64/kernel/unaligned.c > @@ -1336,8 +1336,11 @@ ia64_handle_unaligned (unsigned long ifa, struct pt_regs *regs) > * Don't call tty_write_message() if we're in the kernel; we might > * be holding locks... > */ > - if (user_mode(regs)) > - tty_write_message(current->signal->tty, buf); > + if (user_mode(regs)) { > + struct tty_struct *tty = get_current_tty(); > + tty_write_message(tty, buf); > + tty_kref_put(tty); > + } > buf[len-1] = '\0'; /* drop '\r' */ > /* watch for command names containing %s */ > printk(KERN_WARNING "%s", buf); >