linux-kernel - Re: [RFC][PATCH] PM: Introduce new top level suspend and hibernation callbacks (rev. 2)

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-Id: <200803230044.29132.rjw@sisk.pl>
Date:	Sun, 23 Mar 2008 00:44:27 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	pm list <linux-pm@...ts.linux-foundation.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Greg KH <greg@...ah.com>, Len Brown <lenb@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Alexey Starikovskiy <astarikovskiy@...e.de>,
	David Brownell <david-b@...bell.net>,
	Pavel Machek <pavel@....cz>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [RFC][PATCH] PM: Introduce new top level suspend and hibernation callbacks (rev. 2)

On Sunday, 23 of March 2008, Alan Stern wrote:
> On Sat, 22 Mar 2008, Rafael J. Wysocki wrote:
> 
[--snip--]
> 
> No, you have missed the entire point.  The problem doesn't exist in the
> current code; it exists only if we switch over to using a single list.  
> Routines like dpm_suspend() won't be able to use list_for_each_entry()
> to traverse the list because entries may be removed by other threads
> during the traversal.  Even list_for_each_entry_safe() won't work
> correctly without careful attention to details.

Ah, ok.  Thanks for the clarification.

Doesn't it help that we traverse the list under dpm_list_mtx?  Anyone who
removes an entry is required to take dpm_list_mtx that we're holding while
the list is traversed except when the callbacks are invoked.

The only problem I see is when the device currently being handled is removed
from the list by a concurrent thread.  Is that you were referring to?

Rafael
--
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/