On Tue, 2012-05-01 at 10:31 -0400, Namjae Jeon wrote:
> SCSI host lock push-down patch is not applied in ufs host driver yet.
> After adding it, I tried to remove unneeded spin lock in queuecommand also.
This really isn't the correct thing: you're increasing the lock coverage
not decreasing it.
In the old way, ->queuecommand() was called locked. DEF_SCSI_QCMD() was
a macro we use to avoid converting all the previous methods from locked
to unlocked (it simply acts as a bridge between the new way and the old
way).
In the new way we call ->queuecommand() unlocked and try only to take
the lock when it's needed, if at all. The current ufshcd_queuecommand()
is correct because it only takes the lock when it needs it in
ufshcd_send_command(). A lock push down into that routine might be
possible, but since it's only a couple of bytes, probably not worth it.
James
> Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxx>
> ---
> drivers/scsi/ufs/ufshcd.c | 20 ++++++++++----------
> 1 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 3cb7a08..a134738 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -658,23 +658,23 @@ static void ufshcd_compose_upiu(struct ufshcd_lrb *lrbp)
> }
>
> /**
> - * ufshcd_queuecommand - main entry point for SCSI requests
> + * ufshcd_queuecommand_lck - main entry point for SCSI requests
> * @cmd: command from SCSI Midlayer
> * @done: call back function
> *
> * Returns 0 for success, non-zero in case of failure
> */
> -static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
> +static int
> +ufshcd_queuecommand_lck(struct scsi_cmnd *scp, void (*done)(struct scsi_cmnd *))
> {
> struct ufshcd_lrb *lrbp;
> struct ufs_hba *hba;
> - unsigned long flags;
> int tag;
> int err = 0;
>
> - hba = shost_priv(host);
> + hba = shost_priv(scp->device->host);
>
> - tag = cmd->request->tag;
> + tag = scp->request->tag;
>
> if (hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL) {
> err = SCSI_MLQUEUE_HOST_BUSY;
> @@ -683,11 +683,11 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
>
> lrbp = &hba->lrb[tag];
>
> - lrbp->cmd = cmd;
> + lrbp->cmd = scp;
> lrbp->sense_bufflen = SCSI_SENSE_BUFFERSIZE;
> - lrbp->sense_buffer = cmd->sense_buffer;
> + lrbp->sense_buffer = scp->sense_buffer;
> lrbp->task_tag = tag;
> - lrbp->lun = cmd->device->lun;
> + lrbp->lun = scp->device->lun;
>
> lrbp->command_type = UTP_CMD_TYPE_SCSI;
>
> @@ -698,13 +698,13 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
> goto out;
>
> /* issue command to the controller */
> - spin_lock_irqsave(hba->host->host_lock, flags);
> ufshcd_send_command(hba, tag);
> - spin_unlock_irqrestore(hba->host->host_lock, flags);
> out:
> return err;
> }
>
> +static DEF_SCSI_QCMD(ufshcd_queuecommand);
> +
> /**
> * ufshcd_memory_alloc - allocate memory for host memory space data structures
> * @hba: per adapter instance
--
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