On Sat, Jan 29, 2011 at 02:38:22PM -0800, Nicholas A. Bellinger wrote:
> Hi Stephen and Co,
>
> Attached is a quick patch to enable modern SCSI host_lock' less
> operation for the HPSA SCSI LLD driver on >= .37 kernels. After an
> initial LLD conversion and review, I would like to verify with you that
> the following calls are currently protected by HPDA LLD internal locks
> that disable interrupts from the newly renamed hpsa_scsi_queue_command()
> dispatcher below..
>
> *) For cmd_alloc(), struct ctlr_info *h->lock + spin_lock_irqsave() is
> obtained and released.
Yes (but not inside cmd_alloc()), the lock is taken to protect
the bitmap that's used to track allocated commands, h->cmd_pool_bits.
>
> *) For enqueue_cmd_and_start_io(), struct ctlr_info *h->lock +
> spin_lock_irqsave() is obtained for addQ() + start_io() and released.
Yes.
>
> So the one new piece wrt to host_lock less mode that is *not* protected
> in hpsa_scsi_queue_command() is the call to hpsa_scatter_gather(). This
> should be OK to get called without h->lock held w/ spin_lock_irqsave(),
> yes..?
Yes, hpsa_scatter_gather() doesn't require the lock to be held.
>
> So far this patch has been compile tested only. Please have a look and
> comment.
Nothing obviously wrong that I see.
-- steve
>
> Thanks!
>
> --nab
>
> diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
> index 12deffc..e205f33 100644
> --- a/drivers/scsi/hpsa.c
> +++ b/drivers/scsi/hpsa.c
> @@ -1906,9 +1906,11 @@ sglist_finished:
> return 0;
> }
>
> -
> -static int hpsa_scsi_queue_command_lck(struct scsi_cmnd *cmd,
> - void (*done)(struct scsi_cmnd *))
> +/*
> + * Running in struct Scsi_Host->host_lock less mode using LLD internal
> + * struct ctlr_info *h->lock w/ spin_lock_irqsave() protection.
> + */
> +static int hpsa_scsi_queue_command(struct Scsi_Host *sh, struct scsi_cmnd *cmd)
> {
> struct ctlr_info *h;
> struct hpsa_scsi_dev_t *dev;
> @@ -1921,7 +1923,7 @@ static int hpsa_scsi_queue_command_lck(struct scsi_cmnd *cmd,
> dev = cmd->device->hostdata;
> if (!dev) {
> cmd->result = DID_NO_CONNECT << 16;
> - done(cmd);
> + cmd->scsi_done(cmd);
> return 0;
> }
> memcpy(scsi3addr, dev->scsi3addr, sizeof(scsi3addr));
> @@ -1936,9 +1938,6 @@ static int hpsa_scsi_queue_command_lck(struct scsi_cmnd *cmd,
> }
>
> /* Fill in the command list header */
> -
> - cmd->scsi_done = done; /* save this for use by completion code */
> -
> /* save c in case we have to abort it */
> cmd->host_scribble = (unsigned char *) c;
>
> @@ -2001,8 +2000,6 @@ static int hpsa_scsi_queue_command_lck(struct scsi_cmnd *cmd,
> return 0;
> }
>
> -static DEF_SCSI_QCMD(hpsa_scsi_queue_command)
> -
> static void hpsa_scan_start(struct Scsi_Host *sh)
> {
> struct ctlr_info *h = shost_to_hba(sh);
>
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