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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Jeff Dike <jdike@addtoit.com>
Cc: Paul Mackerras <paulus@samba.org>,
	Nicholas Miell <nmiell@comcast.net>,
	Davide Libenzi <davidel@xmailserver.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Linux Kernel list <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: signalfd API issues (was Re: [PATCH/RFC] signal races/bugs, losing TIF_SIGPENDING and other woes)
Date: Thu, 07 Jun 2007 13:29:23 +1000	[thread overview]
Message-ID: <1181186963.14818.15.camel@localhost.localdomain> (raw)
In-Reply-To: <20070607022002.GA11977@c2.user-mode-linux.org>

On Wed, 2007-06-06 at 22:20 -0400, Jeff Dike wrote:
> On Thu, Jun 07, 2007 at 08:43:42AM +1000, Paul Mackerras wrote:
> > What Ben was talking about was stealing a synchronous SEGV from a task
> > without stopping it, and as Ben says that makes no sense.
> > Intercepting a signal and stopping the task is reasonable, and that is
> > what ptrace does, and I assume also UML.
> 
> It is, but I can also see UML stealing the SEGV from the child.  The
> UML skas does this - a ptrace extension, PTRACE_FAULTINFO, is used to
> extract page fault information from the child, and other pieces of the
> patch are used to fix the fault without the child continuing until
> it's fixed.  So, in this case, the child never sees the SEGV.

But you use ptrace and don't steal signals with dequeue_signal() on a
live other task, which is ok.

Ben.



  reply	other threads:[~2007-06-07  3:29 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-06-05  1:25 [PATCH/RFC] signal races/bugs, losing TIF_SIGPENDING and other woes Benjamin Herrenschmidt
2007-06-05  1:44 ` Linus Torvalds
2007-06-05  2:10   ` Benjamin Herrenschmidt
2007-06-05  2:38     ` Davide Libenzi
2007-06-05  3:22       ` Benjamin Herrenschmidt
2007-06-05  6:09         ` Nicholas Miell
2007-06-05  7:27           ` Benjamin Herrenschmidt
2007-06-05 23:51             ` Nicholas Miell
2007-06-06  0:03               ` Benjamin Herrenschmidt
2007-06-06  0:11               ` Davide Libenzi
2007-06-06  0:15                 ` Nicholas Miell
2007-06-06  0:37                   ` Davide Libenzi
2007-06-06  0:58                     ` signalfd API issues (was Re: [PATCH/RFC] signal races/bugs, losing TIF_SIGPENDING and other woes) Nicholas Miell
2007-06-06  2:50                       ` Benjamin Herrenschmidt
2007-06-06  3:29                         ` Davide Libenzi
2007-06-06  3:37                           ` Linus Torvalds
2007-06-06  4:08                             ` Nicholas Miell
2007-06-06  4:18                               ` Benjamin Herrenschmidt
2007-06-06  4:35                             ` Davide Libenzi
2007-06-06  6:47                             ` Benjamin Herrenschmidt
2007-06-06 22:36                               ` Davide Libenzi
2007-06-06  3:52                           ` Benjamin Herrenschmidt
2007-06-06 12:52                         ` Jeff Dike
2007-06-06 22:43                           ` Paul Mackerras
2007-06-07  2:20                             ` Jeff Dike
2007-06-07  3:29                               ` Benjamin Herrenschmidt [this message]
2007-06-07 13:59                                 ` Jeff Dike
2007-06-07  3:21                           ` Benjamin Herrenschmidt
2007-06-05 15:52     ` [PATCH/RFC] signal races/bugs, losing TIF_SIGPENDING and other woes Davide Libenzi
2007-06-05 22:15       ` Benjamin Herrenschmidt
2007-06-05 22:50         ` Davide Libenzi
2007-06-05 22:59           ` Benjamin Herrenschmidt
2007-06-06  0:11             ` Davide Libenzi

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