Re: [PATCH 03/12] libsas: Convert to host_lock less w/ interrupts disabled externally

Nicholas A. Bellinger
2010-12-20T09:39:26Z

On Mon, 2010-12-20 at 10:58 +0200, Boaz Harrosh wrote:
> On 12/19/2010 11:21 PM, Nicholas A. Bellinger wrote:
> > From: Nicholas Bellinger <nab@linux-iscsi.org>
> >
> > This patch converts the libsas queuecommand to run in host_lock less mode
> > w/ the new IRQ_DISABLE_SCSI_QCMD() that disables interrupts while calling
> > ->queuecommand() dispatch.
> >
> > Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
> > ---
> > drivers/scsi/libsas/sas_scsi_host.c | 12 ++----------
> > 1 files changed, 2 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
> > index 29251fa..011580f 100644
> > --- a/drivers/scsi/libsas/sas_scsi_host.c
> > +++ b/drivers/scsi/libsas/sas_scsi_host.c
> > @@ -185,24 +185,17 @@ int sas_queue_up(struct sas_task *task)
> > /**
> > * sas_queuecommand -- Enqueue a command for processing
> > * @parameters: See SCSI Core documentation
> > - *
> > - * Note: XXX: Remove the host unlock/lock pair when SCSI Core can
> > - * call us without holding an IRQ spinlock...
> > */
> > -static int sas_queuecommand_lck(struct scsi_cmnd *cmd,
> > +static int sas_queuecommand_irq_disable(struct scsi_cmnd *cmd,
> > void (*scsi_done)(struct scsi_cmnd *))
> > - __releases(host->host_lock)
> > __acquires(dev->sata_dev.ap->lock)
> > __releases(dev->sata_dev.ap->lock)
> > - __acquires(host->host_lock)
> > {
> > int res = 0;
> > struct domain_device *dev = cmd_to_domain_dev(cmd);
> > struct Scsi_Host *host = cmd->device->host;
> > struct sas_internal *i = to_sas_internal(host->transportt);
> >
> > - spin_unlock_irq(host->host_lock);
> > -
> > {
> > struct sas_ha_struct *sas_ha = dev->port->ha;
> > struct sas_task *task;
> > @@ -250,11 +243,10 @@ static int sas_queuecommand_lck(struct scsi_cmnd *cmd,
> > }
> > }
> > out:
> > - spin_lock_irq(host->host_lock);
> > return res;
> > }
> >
> > -DEF_SCSI_QCMD(sas_queuecommand)
> > +IRQ_DISABLE_SCSI_QCMD(sas_queuecommand)
> >
>
> I hate this new macro. It is so simple by now. And anyway you are
> doing them one by one and auditing the code. Please completely drop
> this macro and open code it. There is no "safety" argument to this
> ugliness, any more.
>
> (Completely drop the [PATCH 02/12] scsi: Add IRQ_DISABLE_SCSI_QCMD wrapper
> patch and redo the users)
>

Hi Boaz,

I am happy to open code the handful of remaining LLDs that need proper
conversion for lock_less-LLDs-for-38-v4 and drop patch #2 now that we
have isolated the first round of host_lock-less LLD conversions.

Best Regards,

--nab