linux-kernel - Re: [PATCH 10/12] scsi: megaraid_sas - Add input parameter for max

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Message-ID: <1281103916.29178.5.camel@mulgrave.site>
Date:	Fri, 06 Aug 2010 09:11:55 -0500
From:	James Bottomley <James.Bottomley@...e.de>
To:	Hannes Reinecke <hare@...e.de>
Cc:	"Yang, Bo" <Bo.Yang@....com>,
	"'linux-scsi@...r.kernel.org'" <linux-scsi@...r.kernel.org>,
	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 10/12] scsi: megaraid_sas - Add input parameter for
 max_sectors

On Fri, 2010-08-06 at 12:43 +0200, Hannes Reinecke wrote:
> Yang, Bo wrote:
> > RESUBMIT requested by James Bottomley:
> > 
> > Driver add the input parameters support for max_sectors for our gen2 chip.  Customer can
> > Set the max_sectors support to 1MB for gen2 chip during the driver load.
> > 
> > Signed-off-by Bo Yang<bo.yang@....com>
> > 
> > ---
> > drivers/scsi/megaraid/megaraid_sas.c |   74 +++++++++++++++++++++++++++++++++++
> >  drivers/scsi/megaraid/megaraid_sas.h |    1
> >  2 files changed, 75 insertions(+)
> > 
> > diff -rupN old/drivers/scsi/megaraid/megaraid_sas.c new/drivers/scsi/megaraid/megaraid_sas.c
> > --- old/drivers/scsi/megaraid/megaraid_sas.c	2010-06-08 09:04:38.000000000 -0400
> > +++ new/drivers/scsi/megaraid/megaraid_sas.c	2010-06-08 09:51:56.000000000 -0400
> > @@ -57,6 +57,15 @@ module_param_named(poll_mode_io, poll_mo
> >  MODULE_PARM_DESC(poll_mode_io,
> >  	"Complete cmds from IO path, (default=0)");
> >  
> > +/*
> > + * Number of sectors per IO command
> > + * Will be set in megasas_init_mfi if user does not provide
> > + */
> > +static unsigned int max_sectors;
> > +module_param_named(max_sectors, max_sectors, int, 0);
> > +MODULE_PARM_DESC(max_sectors,
> > +	"Maximum number of sectors per IO command");
> > +
> >  MODULE_LICENSE("GPL");
> >  MODULE_VERSION(MEGASAS_VERSION);
> >  MODULE_AUTHOR("megaraidlinux@....com");
> > @@ -3566,6 +3575,32 @@ static int megasas_start_aen(struct mega
> >  				    class_locale.word);
> >  }
> >  
> > +static ssize_t
> > +sysfs_max_sectors_read(struct kobject *kobj, struct bin_attribute *bin_attr,
> > +			char *buf, loff_t off, size_t count)
> > +{
> > +	struct device *dev = container_of(kobj, struct device, kobj);
> > +
> > +	struct Scsi_Host *host = class_to_shost(dev);
> > +
> > +	struct megasas_instance *instance =
> > +				(struct megasas_instance *)host->hostdata;
> > +
> > +	count = sprintf(buf, "%u\n", instance->max_sectors_per_req);
> > +
> > +	return count+1;
> > +}
> > +
> > +static struct bin_attribute sysfs_max_sectors_attr = {
> > +	.attr = {
> > +		.name = "max_sectors",
> > +		.mode = S_IRUSR|S_IRGRP|S_IROTH,
> > +		.owner = THIS_MODULE,
> > +	},
> > +	.size = 7,
> > +	.read = sysfs_max_sectors_read,
> > +};
> > +
> >  /**
> >   * megasas_io_attach -	Attaches this driver to SCSI mid-layer
> >   * @instance:		Adapter soft state
> > @@ -3573,6 +3608,7 @@ static int megasas_start_aen(struct mega
> >  static int megasas_io_attach(struct megasas_instance *instance)
> >  {
> >  	struct Scsi_Host *host = instance->host;
> > +	u32		error;
> >  
> >  	/*
> >  	 * Export parameters required by SCSI mid-layer
> > @@ -3588,6 +3624,27 @@ static int megasas_io_attach(struct mega
> >  			instance->max_fw_cmds - MEGASAS_INT_CMDS;
> >  	host->this_id = instance->init_id;
> >  	host->sg_tablesize = instance->max_num_sge;
> > +	/*
> > +	 * Check if the module parameter value for max_sectors can be used
> > +	 */
> > +	if (max_sectors && max_sectors < instance->max_sectors_per_req)
> > +		instance->max_sectors_per_req = max_sectors;
> > +	else {
> > +		if (max_sectors) {
> > +			if (((instance->pdev->device ==
> > +				PCI_DEVICE_ID_LSI_SAS1078GEN2) ||
> > +				(instance->pdev->device ==
> > +				PCI_DEVICE_ID_LSI_SAS0079GEN2)) &&
> > +				(max_sectors <= MEGASAS_MAX_SECTORS)) {
> > +				instance->max_sectors_per_req = max_sectors;
> > +			} else {
> > +			printk(KERN_INFO "megasas: max_sectors should be > 0"
> > +				"and <= %d (or < 1MB for GEN2 controller)\n",
> > +				instance->max_sectors_per_req);
> > +			}
> > +		}
> > +	}
> > +
> >  	host->max_sectors = instance->max_sectors_per_req;
> >  	host->cmd_per_lun = 128;
> >  	host->max_channel = MEGASAS_MAX_CHANNELS - 1;
> > @@ -3604,10 +3661,27 @@ static int megasas_io_attach(struct mega
> >  	}
> >  
> >  	/*
> > +	 * Create sysfs entries for module paramaters
> > +	 */
> > +	error = sysfs_create_bin_file(&instance->host->shost_dev.kobj,
> > +			&sysfs_max_sectors_attr);
> > +
> Errm. sysfs_create_bin_file? 
> Do you expect a user to paste binary values in there?
> Please use the standard interface here.
> sysfs_create_bin_file should only be used for 'real' binary values,
> like raw f/w commands.

Yes, sorry, didn't look at this one too closely.  I thought the whole
patch was pointless since the value gets passed into the host template,
which goes to block, so it's available
under /sys/block/sd<X>/queue/max_hw_sectors_kb

James


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