From: Roland Dreier <rdreier@cisco.com>
To: Stefan Roscher <ossrosch@linux.vnet.ibm.com>
Cc: fenkes@de.ibm.com, LKML <linux-kernel@vger.kernel.org>,
OF-EWG <ewg@lists.openfabrics.org>,
LinuxPPC-Dev <linuxppc-dev@ozlabs.org>,
raisch@de.ibm.com, OF-General <general@lists.openfabrics.org>
Subject: Re: [PATCH] IB/ehca: Allocate event queue size depending on max number of CQs and QPs
Date: Tue, 29 Apr 2008 09:43:42 -0700 [thread overview]
Message-ID: <adafxt4y5kx.fsf@cisco.com> (raw)
In-Reply-To: <200804291744.17235.ossrosch@linux.vnet.ibm.com> (Stefan Roscher's message of "Tue, 29 Apr 2008 17:44:15 +0200")
>
> Signed-off-by: Stefan Roscher <stefan.roscher at de.ibm.com>
Kind of an inadequate changelog ;)
Is this a fix or an enhancement or what?
> + if (atomic_read(&shca->num_cqs) >= ehca_max_cq) {
> + if (atomic_read(&shca->num_qps) >= ehca_max_qp) {
These are racy in the sense that multiple simultaneous calls to
create_cq/create_qp might end up exceeding the ehca_max_cq limit. Is
that an issue?
You could close the race by using atomic_add_unless() and testing the
return value (and being careful to do atomic_dec() on error paths after
you bump num_cqs/num_qps).
- R.
WARNING: multiple messages have this Message-ID (diff)
From: Roland Dreier <rdreier@cisco.com>
To: Stefan Roscher <ossrosch@linux.vnet.ibm.com>
Cc: "LinuxPPC-Dev" <linuxppc-dev@ozlabs.org>,
LKML <linux-kernel@vger.kernel.org>,
"OF-General" <general@lists.openfabrics.org>,
Roland Dreier <rolandd@cisco.com>,
"OF-EWG" <ewg@lists.openfabrics.org>,
hnguyen@de.ibm.com, raisch@de.ibm.com, fenkes@de.ibm.com
Subject: Re: [PATCH] IB/ehca: Allocate event queue size depending on max number of CQs and QPs
Date: Tue, 29 Apr 2008 09:43:42 -0700 [thread overview]
Message-ID: <adafxt4y5kx.fsf@cisco.com> (raw)
In-Reply-To: <200804291744.17235.ossrosch@linux.vnet.ibm.com> (Stefan Roscher's message of "Tue, 29 Apr 2008 17:44:15 +0200")
>
> Signed-off-by: Stefan Roscher <stefan.roscher at de.ibm.com>
Kind of an inadequate changelog ;)
Is this a fix or an enhancement or what?
> + if (atomic_read(&shca->num_cqs) >= ehca_max_cq) {
> + if (atomic_read(&shca->num_qps) >= ehca_max_qp) {
These are racy in the sense that multiple simultaneous calls to
create_cq/create_qp might end up exceeding the ehca_max_cq limit. Is
that an issue?
You could close the race by using atomic_add_unless() and testing the
return value (and being careful to do atomic_dec() on error paths after
you bump num_cqs/num_qps).
- R.
next prev parent reply other threads:[~2008-04-29 16:43 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-29 15:44 [PATCH] IB/ehca: Allocate event queue size depending on max number of CQs and QPs Stefan Roscher
2008-04-29 15:44 ` Stefan Roscher
2008-04-29 16:43 ` Roland Dreier [this message]
2008-04-29 16:43 ` Roland Dreier
2008-04-29 18:15 ` [REPOST][PATCH] " Stefan Roscher
2008-04-29 18:15 ` Stefan Roscher
2008-04-29 18:20 ` Roland Dreier
2008-04-29 18:20 ` Roland Dreier
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