From: Tomas Henzl <thenzl@redhat.com>
Date: Wed, 6 Feb 2008 22:13:42 +0100
Subject: [scsi] cciss: update procfs
Message-id: 47AA2306.4080609@redhat.com
O-Subject: Re: [RHEL5.2 PATCH] bz423871: Cciss driver update: procfs
Bugzilla: 423871

This patch resolves the  bz#423871: Cciss driver update: procfs

Posted on http://lkml.org/lkml/2007/12/14/373

This patch changes the entries in /proc/driver/cciss, only the information
about the first logical volume is displayed, the reason for that
is that it should prevent system crashes with many lv's.

Brew build, taskID=1132085

Comment from HP:
This patch modifies our /proc/driver/cciss entries. This is required for
systems that may have many LUNs configured. We can easily stomp on memory
and crash the system. Now we only display information about the first LUN on
each controller. Information on other LUNs can be found in /sys.
One reason for this is on hardware that can support many lv's (128 or
more) we can easily stomp on memory and crash the system when displaying
/proc

Tomas

Acked-by: Chip Coldwell <coldwell@redhat.com>

diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 8570c8a..6dc22bf 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -33,6 +33,7 @@
 #include <linux/blkpg.h>
 #include <linux/timer.h>
 #include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/init.h>
 #include <linux/hdreg.h>
 #include <linux/spinlock.h>
@@ -191,8 +192,6 @@ static void fail_all_cmds(unsigned long ctlr);
 static void cciss_shutdown(struct pci_dev *);
 
 #ifdef CONFIG_PROC_FS
-static int cciss_proc_get_info(char *buffer, char **start, off_t offset,
-			       int length, int *eof, void *data);
 static void cciss_procinit(int i);
 #else
 static void cciss_procinit(int i)
@@ -256,24 +255,46 @@ static inline CommandList_struct *removeQ(CommandList_struct **Qptr,
 #define ENG_GIG 1000000000
 #define ENG_GIG_FACTOR (ENG_GIG/512)
 #define RAID_UNKNOWN 6
+#define ENGAGE_SCSI	"engage scsi"
 static const char *raid_label[] = { "0", "4", "1(1+0)", "5", "5+1", "ADG",
 	"UNKNOWN"
 };
 
 static struct proc_dir_entry *proc_cciss;
 
-static int cciss_proc_get_info(char *buffer, char **start, off_t offset,
-			       int length, int *eof, void *data)
+static void cciss_seq_show_header(struct seq_file *seq)
 {
-	off_t pos = 0;
-	off_t len = 0;
-	int size, i, ctlr;
-	ctlr_info_t *h = (ctlr_info_t *) data;
-	drive_info_struct *drv;
-	unsigned long flags;
-	sector_t vol_sz, vol_sz_frac;
+	ctlr_info_t *h = seq->private;
+
+	seq_printf(seq, "%s: HP %s Controller\n"
+		"Board ID: 0x%08lx\n"
+		"Firmware Version: %c%c%c%c\n"
+		"IRQ: %d\n"
+		"Logical drives: %d\n"
+		"Sector size: %d\n"
+		"Current Q depth: %d\n"
+		"Current # commands on controller: %d\n"
+		"Max Q depth since init: %d\n"
+		"Max # commands on controller since init: %d\n"
+		"Max SG entries since init: %d\n",
+		h->devname,
+		h->product_name,
+		(unsigned long)h->board_id,
+		h->firm_ver[0], h->firm_ver[1], h->firm_ver[2],
+		h->firm_ver[3], (unsigned int)h->intr[SIMPLE_MODE_INT],
+		h->num_luns,
+		h->cciss_sector_size,
+		h->Qdepth, h->commands_outstanding,
+		h->maxQsinceinit, h->max_outstanding, h->maxSG);
+
+	cciss_seq_tape_report (seq, h->ctlr);
+}
 
-	ctlr = h->ctlr;
+static void *cciss_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	ctlr_info_t *h = seq->private;
+	unsigned ctlr = h->ctlr;
+	unsigned long flags;
 
 	/* prevent displaying bogus info during configuration
 	 * or deconfiguration of a logical volume
@@ -281,115 +302,154 @@ static int cciss_proc_get_info(char *buffer, char **start, off_t offset,
 	spin_lock_irqsave(CCISS_LOCK(ctlr), flags);
 	if (h->busy_configuring) {
 		spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
-		return -EBUSY;
+		return ERR_PTR(-EBUSY);
 	}
 	h->busy_configuring = 1;
 	spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
 
-	size = sprintf(buffer, "%s: HP %s Controller\n"
-		       "Board ID: 0x%08lx\n"
-		       "Firmware Version: %c%c%c%c\n"
-		       "IRQ: %d\n"
-		       "Logical drives: %d\n"
-		       "Sector size: %d\n"
-		       "Current Q depth: %d\n"
-		       "Current # commands on controller: %d\n"
-		       "Max Q depth since init: %d\n"
-		       "Max # commands on controller since init: %d\n"
-		       "Max SG entries since init: %d\n\n",
-		       h->devname,
-		       h->product_name,
-		       (unsigned long)h->board_id,
-		       h->firm_ver[0], h->firm_ver[1], h->firm_ver[2],
-		       h->firm_ver[3], (unsigned int)h->intr[SIMPLE_MODE_INT],
-		       h->num_luns,
-		       h->cciss_sector_size,
-		       h->Qdepth, h->commands_outstanding,
-		       h->maxQsinceinit, h->max_outstanding, h->maxSG);
-
-	pos += size;
-	len += size;
-	cciss_proc_tape_report(ctlr, buffer, &pos, &len);
-	for (i = 0; i <= h->highest_lun; i++) {
-
-		drv = &h->drv[i];
-		if (drv->heads == 0)
-			continue;
+	if (*pos == 0)
+		cciss_seq_show_header(seq);
 
-		vol_sz = drv->nr_blocks;
-		vol_sz_frac = sector_div(vol_sz, ENG_GIG_FACTOR);
-		vol_sz_frac *= 100;
-		sector_div(vol_sz_frac, ENG_GIG_FACTOR);
+	return pos;
+}
+
+static int cciss_seq_show(struct seq_file *seq, void *v)
+{
+	sector_t vol_sz, vol_sz_frac;
+	ctlr_info_t *h = seq->private;
+	unsigned ctlr = h->ctlr;
+	loff_t *pos = v;
+	drive_info_struct *drv = &h->drv[*pos];
+
+	if (*pos > h->highest_lun)
+		return 0;
+
+	if (drv->heads == 0)
+		return 0;
+
+	vol_sz = drv->nr_blocks;
+	vol_sz_frac = sector_div(vol_sz, ENG_GIG_FACTOR);
+	vol_sz_frac *= 100;
+	sector_div(vol_sz_frac, ENG_GIG_FACTOR);
+
+	if (drv->raid_level > 5)
+		drv->raid_level = RAID_UNKNOWN;
+	seq_printf(seq, "cciss/c%dd%d:"
+			"\t%4u.%02uGB\tRAID %s\n",
+			ctlr, *pos, (int)vol_sz, (int)vol_sz_frac,
+			raid_label[drv->raid_level]);
+
+	return 0;
+}
+
+static void *cciss_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	ctlr_info_t *h = seq->private;
+
+	if (*pos > h->highest_lun)
+		return NULL;
+	*pos += 1;
+
+	return pos;
+}
+
+static void cciss_seq_stop(struct seq_file *seq, void *v)
+{
+	ctlr_info_t *h = seq->private;
+
+	/* Only reset h->busy_configuring if we succeeded in setting
+	 * it during cciss_seq_start. */
+	if (v == ERR_PTR(-EBUSY))
+		return;
 
-		if (drv->raid_level > 5)
-			drv->raid_level = RAID_UNKNOWN;
-		size = sprintf(buffer + len, "cciss/c%dd%d:"
-			       "\t%4u.%02uGB\tRAID %s\n",
-			       ctlr, i, (int)vol_sz, (int)vol_sz_frac,
-			       raid_label[drv->raid_level]);
-		pos += size;
-		len += size;
-	}
-
-	*eof = 1;
-	*start = buffer + offset;
-	len -= offset;
-	if (len > length)
-		len = length;
 	h->busy_configuring = 0;
-	return len;
 }
 
-static int
-cciss_proc_write(struct file *file, const char __user *buffer,
-		 unsigned long count, void *data)
+static struct seq_operations cciss_seq_ops = {
+	.start = cciss_seq_start,
+	.show  = cciss_seq_show,
+	.next  = cciss_seq_next,
+	.stop  = cciss_seq_stop,
+};
+
+static int cciss_seq_open(struct inode *inode, struct file *file)
 {
-	unsigned char cmd[80];
-	int len;
-#ifdef CONFIG_CISS_SCSI_TAPE
-	ctlr_info_t *h = (ctlr_info_t *) data;
-	int rc;
+	int ret = seq_open(file, &cciss_seq_ops);
+	struct seq_file *seq = file->private_data;
+
+	if (!ret)
+		seq->private = PDE(inode)->data;
+
+	return ret;
+}
+
+static ssize_t
+cciss_proc_write(struct file *file, const char __user *buf,
+		 size_t length, loff_t *ppos)
+{
+	struct seq_file *seq = file->private_data;
+	ctlr_info_t *h = seq->private;
+	int err, rc;
+	char *buffer;
+
+
+#ifndef CONFIG_CISS_SCSI_TAPE
+	return -EINVAL;
 #endif
 
-	if (count > sizeof(cmd) - 1)
+	if (!buf || length > PAGE_SIZE - 1)
 		return -EINVAL;
-	if (copy_from_user(cmd, buffer, count))
-		return -EFAULT;
-	cmd[count] = '\0';
-	len = strlen(cmd);	// above 3 lines ensure safety
-	if (len && cmd[len - 1] == '\n')
-		cmd[--len] = '\0';
-#	ifdef CONFIG_CISS_SCSI_TAPE
-	if (strcmp("engage scsi", cmd) == 0) {
+
+	buffer = (char *)__get_free_page(GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	err = -EFAULT;
+	if (copy_from_user(buffer, buf, length))
+		goto out;
+	buffer[length] = '\0';
+
+	if (strncmp(ENGAGE_SCSI, buffer, sizeof ENGAGE_SCSI - 1) == 0) {
 		rc = cciss_engage_scsi(h->ctlr);
 		if (rc != 0)
-			return -rc;
-		return count;
+			err = -rc;
+		else
+			err = length;
 	}
+	else 
+		err = -EINVAL;
 	/* might be nice to have "disengage" too, but it's not
 	   safely possible. (only 1 module use count, lock issues.) */
-#	endif
-	return -EINVAL;
+
+ out:
+	free_page((unsigned long)buffer);
+	return err;
 }
 
-/*
- * Get us a file in /proc/cciss that says something about each controller.
- * Create /proc/cciss if it doesn't exist yet.
- */
+static struct file_operations cciss_proc_fops = {
+	.owner	 = THIS_MODULE,
+	.open    = cciss_seq_open,
+	.read    = seq_read,
+	.llseek  = seq_lseek,
+	.release = seq_release,
+	.write	 = cciss_proc_write,
+};
+
 static void __devinit cciss_procinit(int i)
 {
 	struct proc_dir_entry *pde;
 
-	if (proc_cciss == NULL) {
+	if (proc_cciss == NULL)
 		proc_cciss = proc_mkdir("cciss", proc_root_driver);
-		if (!proc_cciss)
-			return;
-	}
+	if (!proc_cciss)
+		return;
+
+	pde = create_proc_entry(hba[i]->devname, S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH, proc_cciss);
+	if (!pde)
+		return;
 
-	pde = create_proc_read_entry(hba[i]->devname,
-				     S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH,
-				     proc_cciss, cciss_proc_get_info, hba[i]);
-	pde->write_proc = cciss_proc_write;
+	pde->proc_fops = &cciss_proc_fops;
+	pde->data = hba[i];
 }
 #endif				/* CONFIG_PROC_FS */
 
diff --git a/drivers/block/cciss_scsi.c b/drivers/block/cciss_scsi.c
index b8bca81..c2ebc6f 100644
--- a/drivers/block/cciss_scsi.c
+++ b/drivers/block/cciss_scsi.c
@@ -1440,21 +1440,18 @@ cciss_engage_scsi(int ctlr)
 }
 
 static void
-cciss_proc_tape_report(int ctlr, unsigned char *buffer, off_t *pos, off_t *len)
+cciss_seq_tape_report(struct seq_file *seq, int ctlr)
 {
 	unsigned long flags;
-	int size;
-
-	*pos = *pos -1; *len = *len - 1; // cut off the last trailing newline
 
 	CPQ_TAPE_LOCK(ctlr, flags);
-	size = sprintf(buffer + *len, 
+	seq_printf(seq,
 		"Sequential access devices: %d\n\n",
 			ccissscsi[ctlr].ndevices);
 	CPQ_TAPE_UNLOCK(ctlr, flags);
-	*pos += size; *len += size;
 }
 
+
 /* Need at least one of these error handlers to keep ../scsi/hosts.c from 
  * complaining.  Doing a host- or bus-reset can't do anything good here. 
  * Despite what it might say in scsi_error.c, there may well be commands
@@ -1534,6 +1531,6 @@ static int  cciss_eh_abort_handler(struct scsi_cmnd *scsicmd)
 #define cciss_scsi_setup(cntl_num)
 #define cciss_unregister_scsi(ctlr)
 #define cciss_register_scsi(ctlr)
-#define cciss_proc_tape_report(ctlr, buffer, pos, len)
+#define cciss_seq_tape_report(struct seq_file *seq, int ctlr)
 
 #endif /* CONFIG_CISS_SCSI_TAPE */