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Date: Fri, 19 Sep 2008 17:19:31 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: scameron@...rdog.cca.cpqcorp.net
Cc: linux-kernel@...r.kernel.org, mike.miller@...com, axboe@...nel.dk,
scameron@...rdog.cca.cpqcorp.net
Subject: Re: [patch] cciss: Fix cciss SCSI rescan code to better notice
device changes.
On Thu, 18 Sep 2008 15:07:44 -0500
scameron@...rdog.cca.cpqcorp.net wrote:
>
> Fix cciss SCSI rescan code to better notice device changes.
> If you hot-unplug a tape drive, then hot-plug a different
> tape drive into the same slot in a storage enclosure,
> the cciss driver wouldn't notice anything had changed, as
> it was only looking at the LUN address and device type.
> Now it looks at the inquiry page 0x83 device identifier,
> and vendor and model strings as well.
>
> ...
>
> diff -puN drivers/block/cciss_scsi.c~cciss_fix_hotplug_tape_bug drivers/block/cciss_scsi.c
> --- linux-2.6.27-rc6/drivers/block/cciss_scsi.c~cciss_fix_hotplug_tape_bug 2008-09-18 07:34:58.000000000 -0500
> +++ linux-2.6.27-rc6-scameron/drivers/block/cciss_scsi.c 2008-09-18 07:35:13.000000000 -0500
> @@ -365,7 +365,7 @@ struct scsi2map {
>
> static int
> cciss_scsi_add_entry(int ctlr, int hostno,
> - unsigned char *scsi3addr, int devtype,
> + struct cciss_scsi_dev_t *device,
> struct scsi2map *added, int *nadded)
> {
> /* assumes hba[ctlr]->scsi_ctlr->lock is held */
> @@ -384,12 +384,12 @@ cciss_scsi_add_entry(int ctlr, int hostn
> lun = 0;
> /* Is this device a non-zero lun of a multi-lun device */
> /* byte 4 of the 8-byte LUN addr will contain the logical unit no. */
> - if (scsi3addr[4] != 0) {
> + if (device->scsi3addr[4] != 0) {
> /* Search through our list and find the device which */
> /* has the same 8 byte LUN address, excepting byte 4. */
> /* Assign the same bus and target for this new LUN. */
> /* Use the logical unit number from the firmware. */
> - memcpy(addr1, scsi3addr, 8);
> + memcpy(addr1, device->scsi3addr, 8);
> addr1[4] = 0;
> for (i = 0; i < n; i++) {
> sd = &ccissscsi[ctlr].dev[i];
> @@ -399,7 +399,7 @@ cciss_scsi_add_entry(int ctlr, int hostn
> if (memcmp(addr1, addr2, 8) == 0) {
> bus = sd->bus;
> target = sd->target;
> - lun = scsi3addr[4];
> + lun = device->scsi3addr[4];
> break;
> }
> }
> @@ -420,8 +420,12 @@ cciss_scsi_add_entry(int ctlr, int hostn
> added[*nadded].lun = sd->lun;
> (*nadded)++;
>
> - memcpy(&sd->scsi3addr[0], scsi3addr, 8);
> - sd->devtype = devtype;
> + memcpy(sd->scsi3addr, device->scsi3addr, 8);
> + memcpy(sd->vendor, device->vendor, sizeof(sd->vendor));
> + memcpy(sd->revision, device->revision, sizeof(sd->revision));
> + memcpy(sd->device_id, device->device_id, sizeof(sd->device_id));
> + sd->devtype = device->devtype;
y'know, it would be a lot simpler to just do
*sd = *device;
a few lines up, before assigning sd->bus/target/lun.
Putting these:
@@ -66,6 +66,10 @@ struct cciss_scsi_dev_t {
int devtype;
int bus, target, lun; /* as presented to the OS */
unsigned char scsi3addr[8]; /* as presented to the HW */
+ unsigned char device_id[16]; /* from inquiry pg. 0x83 */
+ unsigned char vendor[8]; /* bytes 8-15 of inquiry data */
+ unsigned char model[16]; /* bytes 16-31 of inquiry data */
+ unsigned char revision[4]; /* bytes 32-35 of inquiry data */
};
into a separate nested structure might make that neater still.
> ccissscsi[ctlr].ndevices++;
>
> /* initially, (before registering with scsi layer) we don't
> @@ -487,6 +491,22 @@ static void fixup_botched_add(int ctlr,
> CPQ_TAPE_UNLOCK(ctlr, flags);
> }
>
> +static int device_is_the_same(struct cciss_scsi_dev_t *dev1,
> + struct cciss_scsi_dev_t *dev2)
`struct cciss_scsi_dev_t' should have been named `struct cciss_scsi_dev',
but I guess I'm a bit late to that party.
> +{
> + return dev1->devtype == dev2->devtype &&
> + memcmp(dev1->scsi3addr, dev2->scsi3addr,
> + sizeof(dev1->scsi3addr)) == 0 &&
> + memcmp(dev1->device_id, dev2->device_id,
> + sizeof(dev1->device_id)) == 0 &&
> + memcmp(dev1->vendor, dev2->vendor,
> + sizeof(dev1->vendor)) == 0 &&
> + memcmp(dev1->model, dev2->model,
> + sizeof(dev1->model)) == 0 &&
> + memcmp(dev1->revision, dev2->revision,
> + sizeof(dev1->revision)) == 0;
> +}
> +
>
> ...
>
> + } else if (found == 1) { /* device is different in some way */
> changes++;
> - printk("cciss%d: device c%db%dt%dl%d type changed "
> - "(device type now %s).\n",
> - ctlr, hostno, csd->bus, csd->target, csd->lun,
> - scsi_device_type(csd->devtype));
> + printk("cciss%d: device c%db%dt%dl%d has changed.\n",
> + ctlr, hostno, csd->bus, csd->target, csd->lun);
> cciss_scsi_remove_entry(ctlr, hostno, i,
> removed, &nremoved);
> /* remove ^^^, hence i not incremented */
> - if (cciss_scsi_add_entry(ctlr, hostno,
> - &sd[j].scsi3addr[0], sd[j].devtype,
> + if (cciss_scsi_add_entry(ctlr, hostno, &sd[j],
> added, &nadded) != 0)
> /* we just removed one, so add can't fail. */
> BUG();
> csd->devtype = sd[j].devtype;
> + memcpy(csd->device_id, sd[j].device_id,
> + sizeof(csd->device_id));
> + memcpy(csd->vendor, sd[j].vendor,
> + sizeof(csd->vendor));
> + memcpy(csd->model, sd[j].model,
> + sizeof(csd->model));
> + memcpy(csd->revision, sd[j].revision,
> + sizeof(csd->revision));
didn't cciss_scsi_add_entry() just do that? I didn't look too closely,
so maybe it didn't, and we're taking two copies for some reason.
Please double-check?
> } else /* device is same as it ever was, */
> i++; /* so just move along. */
> }
>
> ...
>
> +/* Get the device id from inquiry page 0x83 */
> +static int cciss_scsi_get_device_id(ctlr_info_t *c, unsigned char *scsi3addr,
> + unsigned char *device_id, int buflen)
> +{
> + int rc;
> + unsigned char *buf;
> +
> + if (buflen > 16)
> + buflen = 16;
> + buf = kzalloc(64, GFP_KERNEL);
> + if (!buf)
> + return -1;
> + rc = cciss_scsi_do_inquiry(c, scsi3addr, 0x83, buf, 64);
> + if (rc == 0)
> + memcpy(device_id, &buf[8], buflen);
> + kfree(buf);
> + return rc != 0;
> +}
The caller ignores the error return from this function. I guess that's
reasonable, and kzalloc() will have spewed a bit warning anyway..
> static int
> cciss_scsi_do_report_phys_luns(ctlr_info_t *c,
> ReportLunData_struct *buf, int bufsize)
> @@ -1142,25 +1184,21 @@ cciss_update_non_disk_devices(int cntl_n
> ctlr_info_t *c;
> __u32 num_luns=0;
> unsigned char *ch;
> - /* unsigned char found[CCISS_MAX_SCSI_DEVS_PER_HBA]; */
> - struct cciss_scsi_dev_t currentsd[CCISS_MAX_SCSI_DEVS_PER_HBA];
> + struct cciss_scsi_dev_t *currentsd, *this_device;
> int ncurrent=0;
> int reportlunsize = sizeof(*ld_buff) + CISS_MAX_PHYS_LUN * 8;
> int i;
>
> c = (ctlr_info_t *) hba[cntl_num];
> ld_buff = kzalloc(reportlunsize, GFP_KERNEL);
> - if (ld_buff == NULL) {
> - printk(KERN_ERR "cciss: out of memory\n");
> - return;
> - }
> inq_buff = kmalloc(OBDR_TAPE_INQ_SIZE, GFP_KERNEL);
> - if (inq_buff == NULL) {
> - printk(KERN_ERR "cciss: out of memory\n");
> - kfree(ld_buff);
> - return;
> + currentsd = kzalloc(sizeof(*currentsd) *
> + (CCISS_MAX_SCSI_DEVS_PER_HBA+1), GFP_KERNEL);
That's kcalloc().
> + if (ld_buff == NULL || inq_buff == NULL || currentsd == NULL) {
> + printk(KERN_ERR "cciss: out of memory\n");
> + goto out;
> }
> -
> + this_device = ¤tsd[CCISS_MAX_SCSI_DEVS_PER_HBA];
> if (cciss_scsi_do_report_phys_luns(c, ld_buff, reportlunsize) == 0) {
> ch = &ld_buff->LUNListLength[0];
> num_luns = ((ch[0]<<24) | (ch[1]<<16) | (ch[2]<<8) | ch[3]) / 8;
> @@ -1179,23 +1217,34 @@ cciss_update_non_disk_devices(int cntl_n
>
> ...
>
> + for (i = 0; i < num_luns; i++) {
> /* for each physical lun, do an inquiry */
> if (ld_buff->LUN[i][3] & 0xC0) continue;
> memset(inq_buff, 0, OBDR_TAPE_INQ_SIZE);
> memcpy(&scsi3addr[0], &ld_buff->LUN[i][0], 8);
>
> - if (cciss_scsi_do_inquiry(hba[cntl_num], scsi3addr, inq_buff,
> - (unsigned char) OBDR_TAPE_INQ_SIZE) != 0) {
> + if (cciss_scsi_do_inquiry(hba[cntl_num], scsi3addr, 0, inq_buff,
> + (unsigned char) OBDR_TAPE_INQ_SIZE) != 0)
> /* Inquiry failed (msg printed already) */
> - devtype = 0; /* so we will skip this device. */
> - } else /* what kind of device is this? */
> - devtype = (inq_buff[0] & 0x1f);
> + continue; /* so we will skip this device. */
> +
> + this_device->devtype = (inq_buff[0] & 0x1f);
> + this_device->bus = -1;
> + this_device->target = -1;
> + this_device->lun = -1;
> + memcpy(this_device->scsi3addr, scsi3addr, 8);
> + memcpy(this_device->vendor, &inq_buff[8],
> + sizeof(this_device->vendor));
> + memcpy(this_device->model, &inq_buff[16],
> + sizeof(this_device->model));
> + memcpy(this_device->revision, &inq_buff[32],
> + sizeof(this_device->revision));
> + memset(this_device->device_id, 0,
> + sizeof(this_device->device_id));
> + cciss_scsi_get_device_id(hba[cntl_num], scsi3addr,
> + this_device->device_id, sizeof(this_device->device_id));
Quite a bit of duplication. Perhaps a helper function is needed somewhere.
>
> - switch (devtype)
> + switch (this_device->devtype)
> {
> case 0x05: /* CD-ROM */ {
>
>
> ...
>
--
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