s390/sysinfo: convert /proc/sysinfo to seqfile

The current proc implementation of the /proc/sysinfo file writes all
informations contained in all system information blocks to a single
page.
This is done by calling sprintf all the time in the expectation that
everything will fit into a single page. This however is not necessarily
true if the configuration of a machine is very large.
So convert /proc/sysinfo to avoid writing into random memory regions.

For readability reasons a couple of lines are longer than 80 characters.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/sysinfo.c

@@ -25,14 +25,14 @@
 static inline int stsi_0(void)
 {
 	int rc = stsi(NULL, 0, 0, 0);
+
 	return rc == -ENOSYS ? rc : (((unsigned int) rc) >> 28);
 }
 
-static int stsi_1_1_1(struct sysinfo_1_1_1 *info, char *page, int len)
+static void stsi_1_1_1(struct seq_file *m, struct sysinfo_1_1_1 *info)
 {
 	if (stsi(info, 1, 1, 1) == -ENOSYS)
-		return len;
-
+		return;
 	EBCASC(info->manufacturer, sizeof(info->manufacturer));
 	EBCASC(info->type, sizeof(info->type));
 	EBCASC(info->model, sizeof(info->model));
@@ -41,58 +41,45 @@ static int stsi_1_1_1(struct sysinfo_1_1_1 *info, char *page, int len)
 	EBCASC(info->model_capacity, sizeof(info->model_capacity));
 	EBCASC(info->model_perm_cap, sizeof(info->model_perm_cap));
 	EBCASC(info->model_temp_cap, sizeof(info->model_temp_cap));
-	len += sprintf(page + len, "Manufacturer:         %-16.16s\n",
-		       info->manufacturer);
-	len += sprintf(page + len, "Type:                 %-4.4s\n",
-		       info->type);
+	seq_printf(m, "Manufacturer:         %-16.16s\n", info->manufacturer);
+	seq_printf(m, "Type:                 %-4.4s\n", info->type);
+	/*
+	 * Sigh: the model field has been renamed with System z9
+	 * to model_capacity and a new model field has been added
+	 * after the plant field. To avoid confusing older programs
+	 * the "Model:" prints "model_capacity model" or just
+	 * "model_capacity" if the model string is empty .
+	 */
+	seq_printf(m, "Model:                %-16.16s", info->model_capacity);
 	if (info->model[0] != '\0')
-		/*
-		 * Sigh: the model field has been renamed with System z9
-		 * to model_capacity and a new model field has been added
-		 * after the plant field. To avoid confusing older programs
-		 * the "Model:" prints "model_capacity model" or just
-		 * "model_capacity" if the model string is empty .
-		 */
-		len += sprintf(page + len,
-			       "Model:                %-16.16s %-16.16s\n",
-			       info->model_capacity, info->model);
-	else
-		len += sprintf(page + len, "Model:                %-16.16s\n",
-			       info->model_capacity);
-	len += sprintf(page + len, "Sequence Code:        %-16.16s\n",
-		       info->sequence);
-	len += sprintf(page + len, "Plant:                %-4.4s\n",
-		       info->plant);
-	len += sprintf(page + len, "Model Capacity:       %-16.16s %08u\n",
-		       info->model_capacity, *(u32 *) info->model_cap_rating);
+		seq_printf(m, " %-16.16s", info->model);
+	seq_putc(m, '\n');
+	seq_printf(m, "Sequence Code:        %-16.16s\n", info->sequence);
+	seq_printf(m, "Plant:                %-4.4s\n", info->plant);
+	seq_printf(m, "Model Capacity:       %-16.16s %08u\n",
+		   info->model_capacity, *(u32 *) info->model_cap_rating);
 	if (info->model_perm_cap[0] != '\0')
-		len += sprintf(page + len,
-			       "Model Perm. Capacity: %-16.16s %08u\n",
-			       info->model_perm_cap,
-			       *(u32 *) info->model_perm_cap_rating);
+		seq_printf(m, "Model Perm. Capacity: %-16.16s %08u\n",
+			   info->model_perm_cap,
+			   *(u32 *) info->model_perm_cap_rating);
 	if (info->model_temp_cap[0] != '\0')
-		len += sprintf(page + len,
-			       "Model Temp. Capacity: %-16.16s %08u\n",
-			       info->model_temp_cap,
-			       *(u32 *) info->model_temp_cap_rating);
+		seq_printf(m, "Model Temp. Capacity: %-16.16s %08u\n",
+			   info->model_temp_cap,
+			   *(u32 *) info->model_temp_cap_rating);
 	if (info->cai) {
-		len += sprintf(page + len,
-			       "Capacity Adj. Ind.:   %d\n",
-			       info->cai);
-		len += sprintf(page + len, "Capacity Ch. Reason:  %d\n",
-			       info->ccr);
+		seq_printf(m, "Capacity Adj. Ind.:   %d\n", info->cai);
+		seq_printf(m, "Capacity Ch. Reason:  %d\n", info->ccr);
 	}
-	return len;
 }
 
-static int stsi_15_1_x(struct sysinfo_15_1_x *info, char *page, int len)
+static void stsi_15_1_x(struct seq_file *m, struct sysinfo_15_1_x *info)
 {
 	static int max_mnest;
 	int i, rc;
 
-	len += sprintf(page + len, "\n");
+	seq_putc(m, '\n');
 	if (!MACHINE_HAS_TOPOLOGY)
-		return len;
+		return;
 	if (max_mnest) {
 		stsi(info, 15, 1, max_mnest);
 	} else {
@@ -102,181 +89,142 @@ static int stsi_15_1_x(struct sysinfo_15_1_x *info, char *page, int len)
 				break;
 		}
 	}
-	len += sprintf(page + len, "CPU Topology HW:     ");
+	seq_printf(m, "CPU Topology HW:     ");
 	for (i = 0; i < TOPOLOGY_NR_MAG; i++)
-		len += sprintf(page + len, " %d", info->mag[i]);
-	len += sprintf(page + len, "\n");
+		seq_printf(m, " %d", info->mag[i]);
+	seq_putc(m, '\n');
 #ifdef CONFIG_SCHED_MC
 	store_topology(info);
-	len += sprintf(page + len, "CPU Topology SW:     ");
+	seq_printf(m, "CPU Topology SW:     ");
 	for (i = 0; i < TOPOLOGY_NR_MAG; i++)
-		len += sprintf(page + len, " %d", info->mag[i]);
-	len += sprintf(page + len, "\n");
+		seq_printf(m, " %d", info->mag[i]);
+	seq_putc(m, '\n');
 #endif
-	return len;
 }
 
-static int stsi_1_2_2(struct sysinfo_1_2_2 *info, char *page, int len)
+static void stsi_1_2_2(struct seq_file *m, struct sysinfo_1_2_2 *info)
 {
 	struct sysinfo_1_2_2_extension *ext;
 	int i;
 
 	if (stsi(info, 1, 2, 2) == -ENOSYS)
-		return len;
+		return;
 	ext = (struct sysinfo_1_2_2_extension *)
 		((unsigned long) info + info->acc_offset);
-
-	len += sprintf(page + len, "CPUs Total:           %d\n",
-		       info->cpus_total);
-	len += sprintf(page + len, "CPUs Configured:      %d\n",
-		       info->cpus_configured);
-	len += sprintf(page + len, "CPUs Standby:         %d\n",
-		       info->cpus_standby);
-	len += sprintf(page + len, "CPUs Reserved:        %d\n",
-		       info->cpus_reserved);
-
-	if (info->format == 1) {
-		/*
-		 * Sigh 2. According to the specification the alternate
-		 * capability field is a 32 bit floating point number
-		 * if the higher order 8 bits are not zero. Printing
-		 * a floating point number in the kernel is a no-no,
-		 * always print the number as 32 bit unsigned integer.
-		 * The user-space needs to know about the strange
-		 * encoding of the alternate cpu capability.
-		 */
-		len += sprintf(page + len, "Capability:           %u %u\n",
-			       info->capability, ext->alt_capability);
-		for (i = 2; i <= info->cpus_total; i++)
-			len += sprintf(page + len,
-				       "Adjustment %02d-way:    %u %u\n",
-				       i, info->adjustment[i-2],
-				       ext->alt_adjustment[i-2]);
-
-	} else {
-		len += sprintf(page + len, "Capability:           %u\n",
-			       info->capability);
-		for (i = 2; i <= info->cpus_total; i++)
-			len += sprintf(page + len,
-				       "Adjustment %02d-way:    %u\n",
-				       i, info->adjustment[i-2]);
+	seq_printf(m, "CPUs Total:           %d\n", info->cpus_total);
+	seq_printf(m, "CPUs Configured:      %d\n", info->cpus_configured);
+	seq_printf(m, "CPUs Standby:         %d\n", info->cpus_standby);
+	seq_printf(m, "CPUs Reserved:        %d\n", info->cpus_reserved);
+	/*
+	 * Sigh 2. According to the specification the alternate
+	 * capability field is a 32 bit floating point number
+	 * if the higher order 8 bits are not zero. Printing
+	 * a floating point number in the kernel is a no-no,
+	 * always print the number as 32 bit unsigned integer.
+	 * The user-space needs to know about the strange
+	 * encoding of the alternate cpu capability.
+	 */
+	seq_printf(m, "Capability:           %u", info->capability);
+	if (info->format == 1)
+		seq_printf(m, " %u", ext->alt_capability);
+	seq_putc(m, '\n');
+	for (i = 2; i <= info->cpus_total; i++) {
+		seq_printf(m, "Adjustment %02d-way:    %u",
+			   i, info->adjustment[i-2]);
+		if (info->format == 1)
+			seq_printf(m, " %u", ext->alt_adjustment[i-2]);
+		seq_putc(m, '\n');
 	}
-
-	if (info->secondary_capability != 0)
-		len += sprintf(page + len, "Secondary Capability: %d\n",
-			       info->secondary_capability);
-	return len;
+	if (info->secondary_capability)
+		seq_printf(m, "Secondary Capability: %d\n",
+			   info->secondary_capability);
 }
 
-static int stsi_2_2_2(struct sysinfo_2_2_2 *info, char *page, int len)
+static void stsi_2_2_2(struct seq_file *m, struct sysinfo_2_2_2 *info)
 {
 	if (stsi(info, 2, 2, 2) == -ENOSYS)
-		return len;
-
+		return;
 	EBCASC(info->name, sizeof(info->name));
-
-	len += sprintf(page + len, "\n");
-	len += sprintf(page + len, "LPAR Number:          %d\n",
-		       info->lpar_number);
-
-	len += sprintf(page + len, "LPAR Characteristics: ");
+	seq_putc(m, '\n');
+	seq_printf(m, "LPAR Number:          %d\n", info->lpar_number);
+	seq_printf(m, "LPAR Characteristics: ");
 	if (info->characteristics & LPAR_CHAR_DEDICATED)
-		len += sprintf(page + len, "Dedicated ");
+		seq_printf(m, "Dedicated ");
 	if (info->characteristics & LPAR_CHAR_SHARED)
-		len += sprintf(page + len, "Shared ");
+		seq_printf(m, "Shared ");
 	if (info->characteristics & LPAR_CHAR_LIMITED)
-		len += sprintf(page + len, "Limited ");
-	len += sprintf(page + len, "\n");
-
-	len += sprintf(page + len, "LPAR Name:            %-8.8s\n",
-		       info->name);
-
-	len += sprintf(page + len, "LPAR Adjustment:      %d\n",
-		       info->caf);
-
-	len += sprintf(page + len, "LPAR CPUs Total:      %d\n",
-		       info->cpus_total);
-	len += sprintf(page + len, "LPAR CPUs Configured: %d\n",
-		       info->cpus_configured);
-	len += sprintf(page + len, "LPAR CPUs Standby:    %d\n",
-		       info->cpus_standby);
-	len += sprintf(page + len, "LPAR CPUs Reserved:   %d\n",
-		       info->cpus_reserved);
-	len += sprintf(page + len, "LPAR CPUs Dedicated:  %d\n",
-		       info->cpus_dedicated);
-	len += sprintf(page + len, "LPAR CPUs Shared:     %d\n",
-		       info->cpus_shared);
-	return len;
+		seq_printf(m, "Limited ");
+	seq_putc(m, '\n');
+	seq_printf(m, "LPAR Name:            %-8.8s\n", info->name);
+	seq_printf(m, "LPAR Adjustment:      %d\n", info->caf);
+	seq_printf(m, "LPAR CPUs Total:      %d\n", info->cpus_total);
+	seq_printf(m, "LPAR CPUs Configured: %d\n", info->cpus_configured);
+	seq_printf(m, "LPAR CPUs Standby:    %d\n", info->cpus_standby);
+	seq_printf(m, "LPAR CPUs Reserved:   %d\n", info->cpus_reserved);
+	seq_printf(m, "LPAR CPUs Dedicated:  %d\n", info->cpus_dedicated);
+	seq_printf(m, "LPAR CPUs Shared:     %d\n", info->cpus_shared);
 }
 
-static int stsi_3_2_2(struct sysinfo_3_2_2 *info, char *page, int len)
+static void stsi_3_2_2(struct seq_file *m, struct sysinfo_3_2_2 *info)
 {
 	int i;
 
 	if (stsi(info, 3, 2, 2) == -ENOSYS)
-		return len;
+		return;
 	for (i = 0; i < info->count; i++) {
 		EBCASC(info->vm[i].name, sizeof(info->vm[i].name));
 		EBCASC(info->vm[i].cpi, sizeof(info->vm[i].cpi));
-		len += sprintf(page + len, "\n");
-		len += sprintf(page + len, "VM%02d Name:            %-8.8s\n",
-			       i, info->vm[i].name);
-		len += sprintf(page + len, "VM%02d Control Program: %-16.16s\n",
-			       i, info->vm[i].cpi);
-
-		len += sprintf(page + len, "VM%02d Adjustment:      %d\n",
-			       i, info->vm[i].caf);
-
-		len += sprintf(page + len, "VM%02d CPUs Total:      %d\n",
-			       i, info->vm[i].cpus_total);
-		len += sprintf(page + len, "VM%02d CPUs Configured: %d\n",
-			       i, info->vm[i].cpus_configured);
-		len += sprintf(page + len, "VM%02d CPUs Standby:    %d\n",
-			       i, info->vm[i].cpus_standby);
-		len += sprintf(page + len, "VM%02d CPUs Reserved:   %d\n",
-			       i, info->vm[i].cpus_reserved);
+		seq_putc(m, '\n');
+		seq_printf(m, "VM%02d Name:            %-8.8s\n", i, info->vm[i].name);
+		seq_printf(m, "VM%02d Control Program: %-16.16s\n", i, info->vm[i].cpi);
+		seq_printf(m, "VM%02d Adjustment:      %d\n", i, info->vm[i].caf);
+		seq_printf(m, "VM%02d CPUs Total:      %d\n", i, info->vm[i].cpus_total);
+		seq_printf(m, "VM%02d CPUs Configured: %d\n", i, info->vm[i].cpus_configured);
+		seq_printf(m, "VM%02d CPUs Standby:    %d\n", i, info->vm[i].cpus_standby);
+		seq_printf(m, "VM%02d CPUs Reserved:   %d\n", i, info->vm[i].cpus_reserved);
 	}
-	return len;
 }
 
-static int proc_read_sysinfo(char *page, char **start,
-			     off_t off, int count,
-			     int *eof, void *data)
+static int sysinfo_show(struct seq_file *m, void *v)
 {
-	unsigned long info = get_zeroed_page(GFP_KERNEL);
-	int level, len;
+	void *info = (void *)get_zeroed_page(GFP_KERNEL);
+	int level;
 
 	if (!info)
 		return 0;
-
-	len = 0;
 	level = stsi_0();
 	if (level >= 1)
-		len = stsi_1_1_1((struct sysinfo_1_1_1 *) info, page, len);
-
+		stsi_1_1_1(m, info);
 	if (level >= 1)
-		len = stsi_15_1_x((struct sysinfo_15_1_x *) info, page, len);
-
+		stsi_15_1_x(m, info);
 	if (level >= 1)
-		len = stsi_1_2_2((struct sysinfo_1_2_2 *) info, page, len);
-
+		stsi_1_2_2(m, info);
 	if (level >= 2)
-		len = stsi_2_2_2((struct sysinfo_2_2_2 *) info, page, len);
-
+		stsi_2_2_2(m, info);
 	if (level >= 3)
-		len = stsi_3_2_2((struct sysinfo_3_2_2 *) info, page, len);
+		stsi_3_2_2(m, info);
+	free_page((unsigned long)info);
+	return 0;
+}
 
-	free_page(info);
-	return len;
+static int sysinfo_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, sysinfo_show, NULL);
 }
 
-static __init int create_proc_sysinfo(void)
+static const struct file_operations sysinfo_fops = {
+	.open		= sysinfo_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init sysinfo_create_proc(void)
 {
-	create_proc_read_entry("sysinfo", 0444, NULL,
-			       proc_read_sysinfo, NULL);
+	proc_create("sysinfo", 0444, NULL, &sysinfo_fops);
 	return 0;
 }
-device_initcall(create_proc_sysinfo);
+device_initcall(sysinfo_create_proc);
 
 /*
  * Service levels interface.