From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <ecos-bugs-return-10804-listarch-ecos-bugs=sources.redhat.com@sourceware.org>
Received: (qmail 11107 invoked by alias); 9 May 2014 11:48:53 -0000
Mailing-List: contact ecos-bugs-help@sourceware.org; run by ezmlm
Precedence: bulk
List-Id: <ecos-bugs.sourceware.org>
List-Subscribe: <mailto:ecos-bugs-subscribe@sourceware.org>
List-Post: <mailto:ecos-bugs@sourceware.org>
List-Help: <mailto:ecos-bugs-help@sourceware.org>, <http://sourceware.org/lists.html#faqs>
Sender: ecos-bugs-owner@sourceware.org
Received: (qmail 11091 invoked by uid 89); 9 May 2014 11:48:52 -0000
Authentication-Results: sourceware.org; auth=none
X-Virus-Found: No
X-Spam-SWARE-Status: No, score=-2.8 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2
X-HELO: mail.ecoscentric.com
Received: from hagrid.ecoscentric.com (HELO mail.ecoscentric.com) (212.13.207.197)
 by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-SHA encrypted) ESMTPS; Fri, 09 May 2014 11:48:51 +0000
Received: by mail.ecoscentric.com (Postfix, from userid 48)
	id 175784680025; Fri,  9 May 2014 12:48:48 +0100 (BST)
From: bugzilla-daemon@bugs.ecos.sourceware.org
To: unassigned@bugs.ecos.sourceware.org
Subject: [Bug 1001982] New: scheduler must be unlocked atomically on
 thread_entry (in SMP systems)
Date: Fri, 09 May 2014 11:48:00 -0000
X-Bugzilla-Reason: AssignedTo
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: eCos
X-Bugzilla-Component: Kernel
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: critical
X-Bugzilla-Who: christoph.borchert@tu-dortmund.de
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Priority: low
X-Bugzilla-Assigned-To: unassigned@bugs.ecos.sourceware.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform
 op_sys bug_status bug_severity priority component assigned_to reporter cc
Message-ID: <bug-1001982-777@http.bugs.ecos.sourceware.org/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: http://bugs.ecos.sourceware.org/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-SW-Source: 2014/txt/msg00171.txt.bz2

Please do not reply to this email, use the link below.

http://bugs.ecos.sourceware.org/show_bug.cgi?id=1001982

            Bug ID: 1001982
           Summary: scheduler must be unlocked atomically on thread_entry
                    (in SMP systems)
           Product: eCos
           Version: 3.0
            Target: All
  Architecture/Host All
                OS:
            Status: UNCONFIRMED
          Severity: critical
          Priority: low
         Component: Kernel
          Assignee: unassigned@bugs.ecos.sourceware.org
          Reporter: christoph.borchert@tu-dortmund.de
                CC: ecos-bugs@ecos.sourceware.org

Created attachment 2507
  --> http://bugs.ecos.sourceware.org/attachment.cgi?id=2507&action=edit
patch

Dear eCos developers,

on thread startup, the scheduler lock gets unlocked in a loop, testing the lock
status in each loop iteration:

    while( get_sched_lock() != 0 )
        unlock();

On an SMP system (or any other multi-core system), this piece of code is not
valid. Once the lock reaches zero, it could be taken immediately by another
CPU. In such a case, one CPU decrements the scheduler lock held by another CPU
- eventually corrupting kernel data or crashing the system.

Attached is a patch that solves this issue (and which is still valid for
single-core systems).

Best regards,
Christoph

-- 
You are receiving this mail because:
You are the assignee for the bug.