From: Christoph Hellwig <hch@infradead.org>
To: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Cc: linux-scsi <linux-scsi@vger.kernel.org>,
Jeff Garzik <jeff@garzik.org>,
James Bottomley <James.Bottomley@suse.de>,
Christoph Hellwig <hch@lst.de>,
Mike Christie <michaelc@cs.wisc.edu>,
Ravi Anand <ravi.anand@qlogic.com>,
Andrew Vasquez <andrew.vasquez@qlogic.com>,
Joe Eykholt <jeykholt@cisco.com>,
James Smart <james.smart@emulex.com>,
Vasu Dev <vasu.dev@linux.intel.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Andi Kleen <ak@linux.intel.com>, Tejun Heo <tj@kernel.org>,
Mike Anderson <andmike@linux.vnet.ibm.com>,
MPTFusionLinux <DL-MPTFusionLinux@lsi.com>
Subject: Re: [PATCH 03/11] scsi: Add IRQ_DISABLE_SCSI_QCMD wrapper
Date: Wed, 17 Nov 2010 17:27:52 -0500 [thread overview]
Message-ID: <20101117222752.GA26760@infradead.org> (raw)
In-Reply-To: <1290032322-4899-1-git-send-email-nab@linux-iscsi.org>
On Wed, Nov 17, 2010 at 02:18:42PM -0800, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
>
> This patch adds a IRQ_DISABLE_SCSI_QCMD() wrapper macro used by LLDs
> that can now run in host_lock less mode, but still need interrupts disabled
> using local_irq_save() before calling their lld_queuecommand() dispatcher.
>
> jgarzik says this method is in fact slower than doing a spin_lock_irqsave() on
> internal lib_lld_queuecommand() callers (as is done in libiscsi and libata)
> but is still needed by the majority of lock_less LLDs.
It's not an overly helpful macro. There's no reason a driver should
ever disable irqs on it's own without actually taking a lock. Please
invest the additional couple of minutes and do a proper conversion.
next prev parent reply other threads:[~2010-11-17 22:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-17 22:18 [PATCH 03/11] scsi: Add IRQ_DISABLE_SCSI_QCMD wrapper Nicholas A. Bellinger
2010-11-17 22:27 ` Christoph Hellwig [this message]
2010-11-17 22:29 ` Nicholas A. Bellinger
2010-11-17 22:37 ` Christoph Hellwig
2010-11-18 10:25 ` Boaz Harrosh
2010-11-18 23:05 ` Nicholas A. Bellinger
2010-11-18 23:15 ` Jeff Garzik
2010-11-19 0:04 ` Nicholas A. Bellinger
-- strict thread matches above, loose matches on Subject: below --
2010-11-12 0:13 Nicholas A. Bellinger
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