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From: "Suzuki K. Poulose" <suzuki@in.ibm.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Tejun Heo <tj@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
	Christoph Hellwig <hch@lst.de>,
	Masami Hiramatsu <mhiramat@redhat.com>,
	Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
	Daisuke HATAYAMA <d.hatayama@jp.fujitsu.com>,
	Roland McGrath <roland@redhat.com>,
	Amerigo Wang <amwang@redhat.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC] [Patch 0/21] Non disruptive application core dump infrastructure
Date: Thu, 16 Dec 2010 13:27:10 +0530	[thread overview]
Message-ID: <20101216132710.73abf94d@suzukikp> (raw)
In-Reply-To: <20101215115153.GB22304@basil.fritz.box>

On Wed, 15 Dec 2010 12:51:54 +0100
Andi Kleen <andi@firstfloor.org> wrote:

> > 1) A process can trigger a core synchronously, upon an event, say a signal 
> > handler and continue from there. gcore would require a fork(), which is not 
> > safe to use from a signal handler.
> 
> Why is it not safe for a signal?
> 
> From the kernel side it should be. glibc may do some funky things
> on fork, but you could always call the syscall directly.

I came across the following links,

http://sourceware.org/bugzilla/show_bug.cgi?id=4737
https://www.opengroup.org/austin/docs/austin_445.txt

which seem to suggest that fork() is not async-safe due to malloc and the  
fork handlers. But a direct fork syscall by-passing glibc should be safe.

Thanks
Suzuki

> 
> -Andi


  reply	other threads:[~2010-12-16  7:57 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-14  9:52 Suzuki K. Poulose
2010-12-14  9:54 ` [Patch 1/21] Reuse freezable() predicate Suzuki K. Poulose
2010-12-14  9:57 ` [Patch 2/21] Create elfcore-common.c for ELF class independent core generation helpers Suzuki K. Poulose
2010-12-14 10:00 ` [Patch 3/21] Make vma_dump_size() generic Suzuki K. Poulose
2010-12-14 15:53   ` Oleg Nesterov
2010-12-14 10:01 ` [Patch 4/21] Make fill_psinfo generic Suzuki K. Poulose
2010-12-14 15:53   ` Oleg Nesterov
2010-12-14 15:55   ` Linus Torvalds
2010-12-15  2:22     ` Suzuki K. Poulose
2010-12-14 10:03 ` [Patch 5/21] Rename compat versions of the reusable core generation routines Suzuki K. Poulose
2010-12-14 15:57   ` Oleg Nesterov
2010-12-15  2:30     ` Suzuki K. Poulose
2010-12-14 10:04 ` [Patch 6/21] Export the reusable ELF " Suzuki K. Poulose
2010-12-14 10:05 ` [Patch 7/21] Define API for reading arch specif Program Headers for Core Suzuki K. Poulose
2010-12-14 10:08 ` [Patch 8/21] ia64 Implementation of elf_core_copy_extra_phdrs() Suzuki K. Poulose
2010-12-14 10:09 ` [Patch 9/21] UML (i386) " Suzuki K. Poulose
2010-12-14 10:11 ` [Patch 10/21] Create /proc/pid/core entry Suzuki K. Poulose
2010-12-14 10:36   ` Cong Wang
2010-12-14 15:02     ` Suzuki K. Poulose
2010-12-14 10:12 ` [Patch 11/21] Track the core generation requests Suzuki K. Poulose
2010-12-14 10:51   ` Alexey Dobriyan
2010-12-14 16:04   ` Oleg Nesterov
2010-12-14 10:13 ` [Patch 12/21] Check if the process is an ELF executable Suzuki K. Poulose
2010-12-14 16:05   ` Oleg Nesterov
2010-12-14 10:15 ` [Patch 13/21] Freeze / Thaw threads Suzuki K. Poulose
2010-12-14 16:17   ` Oleg Nesterov
2010-12-14 10:16 ` [Patch 14/21] Create ELF header Suzuki K. Poulose
2010-12-14 16:24   ` Oleg Nesterov
2010-12-14 10:17 ` [Patch 15/21] Collect ELF Core notes data Suzuki K. Poulose
2010-12-14 16:37   ` Oleg Nesterov
2010-12-14 10:19 ` [Patch 16/21] Wait for threads to freeze Suzuki K. Poulose
2010-12-14 16:42   ` Oleg Nesterov
2010-12-14 10:20 ` [Patch 17/21] Calculate the size of the core file Suzuki K. Poulose
2010-12-14 10:22 ` [Patch 18/21] Generate the data sections for ELF Core Suzuki K. Poulose
2010-12-15  7:19   ` Cong Wang
2010-12-15 12:46     ` Suzuki K. Poulose
2010-12-16  2:14       ` Cong Wang
2010-12-14 10:24 ` [Patch 19/21] Identify the ELF class of the process Suzuki K. Poulose
2010-12-14 10:26 ` [Patch 20/21] Add supporting for compat ELF class data structures Suzuki K. Poulose
2010-12-14 10:27 ` [Patch 21/21] Compat ELF class Core generation support Suzuki K. Poulose
2010-12-14 10:54 ` [RFC] [Patch 0/21] Non disruptive application core dump infrastructure Alexey Dobriyan
2010-12-14 14:59   ` Suzuki K. Poulose
2010-12-14 15:49 ` Linus Torvalds
2010-12-14 16:03   ` Tejun Heo
2010-12-14 16:19     ` Linus Torvalds
2010-12-14 16:28       ` Tejun Heo
2010-12-15  5:34   ` Suzuki K. Poulose
2010-12-15  9:37     ` Tejun Heo
2010-12-15 11:26       ` Suzuki K. Poulose
2010-12-15 11:51         ` Andi Kleen
2010-12-16  7:57           ` Suzuki K. Poulose [this message]
2010-12-15  1:04 ` KAMEZAWA Hiroyuki
2010-12-15  5:24   ` Suzuki K. Poulose

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