linux-kernel - Re: kobject: delayed kobject release: help find buggy drivers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20130903204442.GA22222@redhat.com>
Date:	Tue, 3 Sep 2013 16:44:42 -0400
From:	Dave Jones <davej@...hat.com>
To:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:	rmk+kernel@....linux.org.uk, gregkh@...uxfoundation.org
Subject: Re: kobject: delayed kobject release: help find buggy drivers

On Tue, Sep 03, 2013 at 06:59:24PM +0000, Linux Kernel wrote:
 > Gitweb:     http://git.kernel.org/linus/;a=commit;h=c817a67ecba7c3c2aaa104796d78f160af60920d
 > Commit:     c817a67ecba7c3c2aaa104796d78f160af60920d
 > Parent:     7c42721fe0c58a848849b43ff558cf2fb86aa35a
 > Author:     Russell King <rmk+kernel@....linux.org.uk>
 > AuthorDate: Thu Jun 27 15:06:14 2013 +0100
 > Committer:  Greg Kroah-Hartman <gregkh@...uxfoundation.org>
 > CommitDate: Thu Jul 25 15:39:04 2013 -0700
 > 
 >     kobject: delayed kobject release: help find buggy drivers
 >     
 >     Implement debugging for kobject release functions.  kobjects are
 >     reference counted, so the drop of the last reference to them is not
 >     predictable. However, the common case is for the last reference to be
 >     the kobject's removal from a subsystem, which results in the release
 >     function being immediately called.
 >     
 >     This can hide subtle bugs, which can occur when another thread holds a
 >     reference to the kobject at the same time that a kobject is removed.
 >     This results in the release method being delayed.
 >     
 >     In order to make these kinds of problems more visible, the following
 >     patch implements a delayed release; this has the effect that the
 >     release function will be out of order with respect to the removal of
 >     the kobject in the same manner that it would be if a reference was
 >     being held.
 >     
 >     This provides us with an easy way to allow driver writers to debug
 >     their drivers and fix otherwise hidden problems.
 >     
 >     Signed-off-by: Russell King <rmk+kernel@....linux.org.uk>
 >     Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

With this enabled, I get a bunch of scrolling oopses immediately after
exiting the bootloader. It happens so early I can't even capture them
over usb-serial, or earlyprintk=dbgp.

And for whatever reason, the printk path while oopsing ignores boot_delay parameter,
so I can't even use that.

any ideas ?

	Dave

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/