[PATCH] convert /proc/devices to use seq_file interface
A Christoph suggested that the /proc/devices file be converted to use the
seq_file interface. This patch does that.
I've obxerved one or two installation that had sufficiently large sans that
they overran the 4k limit on /proc/devices.
Signed-off-by: Neil Horman <nhorman@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/char_dev.c b/fs/char_dev.c
index 3b1b1ee..21195c4 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -35,7 +35,7 @@
unsigned int major;
unsigned int baseminor;
int minorct;
- const char *name;
+ char name[64];
struct file_operations *fops;
struct cdev *cdev; /* will die */
} *chrdevs[MAX_PROBE_HASH];
@@ -46,34 +46,84 @@
return major % MAX_PROBE_HASH;
}
-/* get char device names in somewhat random order */
-int get_chrdev_list(char *page)
+struct chrdev_info {
+ int index;
+ struct char_device_struct *cd;
+};
+
+void *get_next_chrdev(void *dev)
+{
+ struct chrdev_info *info;
+
+ if (dev == NULL) {
+ info = kmalloc(sizeof(*info), GFP_KERNEL);
+ if (!info)
+ goto out;
+ info->index=0;
+ info->cd = chrdevs[info->index];
+ if (info->cd)
+ goto out;
+ } else {
+ info = dev;
+ }
+
+ while (info->index < ARRAY_SIZE(chrdevs)) {
+ if (info->cd)
+ info->cd = info->cd->next;
+ if (info->cd)
+ goto out;
+ /*
+ * No devices on this chain, move to the next
+ */
+ info->index++;
+ info->cd = (info->index < ARRAY_SIZE(chrdevs)) ?
+ chrdevs[info->index] : NULL;
+ if (info->cd)
+ goto out;
+ }
+
+out:
+ return info;
+}
+
+void *acquire_chrdev_list(void)
+{
+ down(&chrdevs_lock);
+ return get_next_chrdev(NULL);
+}
+
+void release_chrdev_list(void *dev)
+{
+ up(&chrdevs_lock);
+ kfree(dev);
+}
+
+
+int count_chrdev_list(void)
{
struct char_device_struct *cd;
- int i, len;
+ int i, count;
- len = sprintf(page, "Character devices:\n");
+ count = 0;
- down(&chrdevs_lock);
for (i = 0; i < ARRAY_SIZE(chrdevs) ; i++) {
- for (cd = chrdevs[i]; cd; cd = cd->next) {
- /*
- * if the current name, plus the 5 extra characters
- * in the device line for this entry
- * would run us off the page, we're done
- */
- if ((len+strlen(cd->name) + 5) >= PAGE_SIZE)
- goto page_full;
-
-
- len += sprintf(page+len, "%3d %s\n",
- cd->major, cd->name);
- }
+ for (cd = chrdevs[i]; cd; cd = cd->next)
+ count++;
}
-page_full:
- up(&chrdevs_lock);
- return len;
+ return count;
+}
+
+int get_chrdev_info(void *dev, int *major, char **name)
+{
+ struct chrdev_info *info = dev;
+
+ if (info->cd == NULL)
+ return 1;
+
+ *major = info->cd->major;
+ *name = info->cd->name;
+ return 0;
}
/*
@@ -121,7 +171,7 @@
cd->major = major;
cd->baseminor = baseminor;
cd->minorct = minorct;
- cd->name = name;
+ strncpy(cd->name,name, 64);
i = major_to_index(major);
diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index 63bf6c0..8f80142 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -20,6 +20,7 @@
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/kernel_stat.h>
+#include <linux/fs.h>
#include <linux/tty.h>
#include <linux/string.h>
#include <linux/mman.h>
@@ -62,7 +63,6 @@
*/
extern int get_hardware_list(char *);
extern int get_stram_list(char *);
-extern int get_chrdev_list(char *);
extern int get_filesystem_list(char *);
extern int get_exec_domain_list(char *);
extern int get_dma_list(char *);
@@ -248,6 +248,154 @@
{
return seq_open(file, &cpuinfo_op);
}
+
+enum devinfo_states {
+ CHR_HDR,
+ CHR_LIST,
+ BLK_HDR,
+ BLK_LIST,
+ DEVINFO_DONE
+};
+
+struct devinfo_state {
+ void *chrdev;
+ void *blkdev;
+ unsigned int num_records;
+ unsigned int cur_record;
+ enum devinfo_states state;
+};
+
+static void *devinfo_start(struct seq_file *f, loff_t *pos)
+{
+ struct devinfo_state *info = f->private;
+
+ if (*pos) {
+ if ((info) && (*pos <= info->num_records))
+ return info;
+ return NULL;
+ }
+ info = kmalloc(sizeof(*info), GFP_KERNEL);
+ f->private = info;
+ info->chrdev = acquire_chrdev_list();
+ info->blkdev = acquire_blkdev_list();
+ info->state = CHR_HDR;
+ info->num_records = count_chrdev_list();
+ info->num_records += count_blkdev_list();
+ info->num_records += 2; /* Character and Block headers */
+ *pos = 1;
+ info->cur_record = *pos;
+ return info;
+}
+
+static void *devinfo_next(struct seq_file *f, void *v, loff_t *pos)
+{
+ int idummy;
+ char *ndummy;
+ struct devinfo_state *info = f->private;
+
+ switch (info->state) {
+ case CHR_HDR:
+ info->state = CHR_LIST;
+ (*pos)++;
+ /*fallthrough*/
+ case CHR_LIST:
+ if (get_chrdev_info(info->chrdev,&idummy,&ndummy)) {
+ /*
+ * The character dev list is complete
+ */
+ info->state = BLK_HDR;
+ } else {
+ info->chrdev = get_next_chrdev(info->chrdev);
+ }
+ (*pos)++;
+ break;
+ case BLK_HDR:
+ info->state = BLK_LIST;
+ (*pos)++;
+ break;
+ case BLK_LIST:
+ if (get_blkdev_info(info->blkdev,&idummy,&ndummy)) {
+ /*
+ * The block dev list is complete
+ */
+ info->state = DEVINFO_DONE;
+ } else {
+ info->blkdev = get_next_blkdev(info->blkdev);
+ }
+ (*pos)++;
+ break;
+ case DEVINFO_DONE:
+ (*pos)++;
+ info->cur_record = *pos;
+ info = NULL;
+ break;
+ default:
+ break;
+ }
+ if (info)
+ info->cur_record = *pos;
+ return info;
+}
+
+static void devinfo_stop(struct seq_file *f, void *v)
+{
+ struct devinfo_state *info = f->private;
+
+ if (info) {
+ release_chrdev_list(info->chrdev);
+ release_blkdev_list(info->blkdev);
+ f->private = NULL;
+ kfree(info);
+ }
+}
+
+static int devinfo_show(struct seq_file *f, void *arg)
+{
+ int major;
+ char *name;
+ struct devinfo_state *info = f->private;
+
+ switch(info->state) {
+ case CHR_HDR:
+ seq_printf(f,"Character devices:\n");
+ /* fallthrough */
+ case CHR_LIST:
+ if (!get_chrdev_info(info->chrdev,&major,&name))
+ seq_printf(f,"%3d %s\n",major,name);
+ break;
+ case BLK_HDR:
+ seq_printf(f,"\nBlock devices:\n");
+ /* fallthrough */
+ case BLK_LIST:
+ if (!get_blkdev_info(info->blkdev,&major,&name))
+ seq_printf(f,"%3d %s\n",major,name);
+ break;
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+static struct seq_operations devinfo_op = {
+ .start = devinfo_start,
+ .next = devinfo_next,
+ .stop = devinfo_stop,
+ .show = devinfo_show,
+};
+
+static int devinfo_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &devinfo_op);
+}
+
+static struct file_operations proc_devinfo_operations = {
+ .open = devinfo_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
static struct file_operations proc_cpuinfo_operations = {
.open = cpuinfo_open,
.read = seq_read,
@@ -450,14 +598,6 @@
.release = single_release,
};
-static int devices_read_proc(char *page, char **start, off_t off,
- int count, int *eof, void *data)
-{
- int len = get_chrdev_list(page);
- len += get_blkdev_list(page+len, len);
- return proc_calc_metrics(page, start, off, count, eof, len);
-}
-
/*
* /proc/interrupts
*/
@@ -582,7 +722,6 @@
#ifdef CONFIG_STRAM_PROC
{"stram", stram_read_proc},
#endif
- {"devices", devices_read_proc},
{"filesystems", filesystems_read_proc},
{"cmdline", cmdline_read_proc},
{"locks", locks_read_proc},
@@ -598,6 +737,7 @@
entry = create_proc_entry("kmsg", S_IRUSR, &proc_root);
if (entry)
entry->proc_fops = &proc_kmsg_operations;
+ create_seq_entry("devices", 0, &proc_devinfo_operations);
create_seq_entry("cpuinfo", 0, &proc_cpuinfo_operations);
create_seq_entry("partitions", 0, &proc_partitions_operations);
create_seq_entry("stat", 0, &proc_stat_operations);