From: Roland Dreier <rdreier@cisco.com>
To: John Blackwood <john.blackwood@ccur.com>
Cc: Sven-Thorsten Dietrich <sdietrich@novell.com>,
linux-rt-users@vger.kernel.org, general@lists.openfabrics.org,
linux-kernel@vger.kernel.org
Subject: Re: [ofa-general] [PATCH] [WORKAROUND] CONFIG_PREEMPT_RT and ib_umad_close() issue
Date: Mon, 17 Sep 2007 08:56:01 -0700 [thread overview]
Message-ID: <adaps0hnv5a.fsf@cisco.com> (raw)
In-Reply-To: <46EE9BCC.1040301@ccur.com> (John Blackwood's message of "Mon, 17 Sep 2007 11:22:52 -0400")
> When using OFED-1.2.5 based infiniband kernel modules on 2.6.22 based
> kernels with the Ingo Molnar CONFIG_PREEMPT_RT applied, then commands
> such as ibnetdiscvoer, smpquery, sminfo, etc. will hang. The problem
> is with the downgrade_write() rw semaphore usage in the
> ib_umad_close() routine.
Can you give a few more details on how PREEMPT_RT changes locking
rules (or just exposes existing bugs maybe?) so that the
downgrade_write() causes the issue? I would like to fix this cleanly
but I don't really understand what the problem is.
- R.
WARNING: multiple messages have this Message-ID (diff)
From: Roland Dreier <rdreier@cisco.com>
To: John Blackwood <john.blackwood@ccur.com>
Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
general@lists.openfabrics.org,
Sven-Thorsten Dietrich <sdietrich@novell.com>
Subject: Re: [ofa-general] [PATCH] [WORKAROUND] CONFIG_PREEMPT_RT and ib_umad_close() issue
Date: Mon, 17 Sep 2007 08:56:01 -0700 [thread overview]
Message-ID: <adaps0hnv5a.fsf@cisco.com> (raw)
In-Reply-To: <46EE9BCC.1040301@ccur.com> (John Blackwood's message of "Mon, 17 Sep 2007 11:22:52 -0400")
> When using OFED-1.2.5 based infiniband kernel modules on 2.6.22 based
> kernels with the Ingo Molnar CONFIG_PREEMPT_RT applied, then commands
> such as ibnetdiscvoer, smpquery, sminfo, etc. will hang. The problem
> is with the downgrade_write() rw semaphore usage in the
> ib_umad_close() routine.
Can you give a few more details on how PREEMPT_RT changes locking
rules (or just exposes existing bugs maybe?) so that the
downgrade_write() causes the issue? I would like to fix this cleanly
but I don't really understand what the problem is.
- R.
next prev parent reply other threads:[~2007-09-17 15:56 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-17 15:22 [PATCH] [WORKAROUND] CONFIG_PREEMPT_RT and ib_umad_close() issue John Blackwood
2007-09-17 15:56 ` Roland Dreier [this message]
2007-09-17 15:56 ` [ofa-general] " Roland Dreier
2007-09-17 17:07 ` Daniel Walker
-- strict thread matches above, loose matches on Subject: below --
2007-09-17 17:19 John Blackwood
2007-09-17 21:40 ` Roland Dreier
2007-09-17 21:40 ` Roland Dreier
2007-09-17 23:41 ` John Blackwood
2007-09-17 23:41 ` John Blackwood
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