android_kernel_xiaomi_sm8350/fs/dlm/debug_fs.c
Josef Bacik 916297aad5 [DLM] keep dlm from panicing when traversing rsb list in debugfs
This problem was originally reported against GFS6.1, but the same issue exists
in upstream DLM.  This patch keeps the rsb iterator assigning under the rsbtbl
list lock.  Each time we process an rsb we grab a reference to it to make sure
it is not freed out from underneath us, and then put it when we get the next rsb
in the list or move onto another list.

Signed-off-by: Josef Bacik <jwhiter@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-07-09 08:22:29 +01:00

395 lines
8.8 KiB
C

/******************************************************************************
*******************************************************************************
**
** Copyright (C) 2005 Red Hat, Inc. All rights reserved.
**
** This copyrighted material is made available to anyone wishing to use,
** modify, copy, or redistribute it subject to the terms and conditions
** of the GNU General Public License v.2.
**
*******************************************************************************
******************************************************************************/
#include <linux/pagemap.h>
#include <linux/seq_file.h>
#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/debugfs.h>
#include "dlm_internal.h"
#include "lock.h"
#define DLM_DEBUG_BUF_LEN 4096
static char debug_buf[DLM_DEBUG_BUF_LEN];
static struct mutex debug_buf_lock;
static struct dentry *dlm_root;
struct rsb_iter {
int entry;
struct dlm_ls *ls;
struct list_head *next;
struct dlm_rsb *rsb;
};
/*
* dump all rsb's in the lockspace hash table
*/
static char *print_lockmode(int mode)
{
switch (mode) {
case DLM_LOCK_IV:
return "--";
case DLM_LOCK_NL:
return "NL";
case DLM_LOCK_CR:
return "CR";
case DLM_LOCK_CW:
return "CW";
case DLM_LOCK_PR:
return "PR";
case DLM_LOCK_PW:
return "PW";
case DLM_LOCK_EX:
return "EX";
default:
return "??";
}
}
static void print_lock(struct seq_file *s, struct dlm_lkb *lkb,
struct dlm_rsb *res)
{
seq_printf(s, "%08x %s", lkb->lkb_id, print_lockmode(lkb->lkb_grmode));
if (lkb->lkb_status == DLM_LKSTS_CONVERT
|| lkb->lkb_status == DLM_LKSTS_WAITING)
seq_printf(s, " (%s)", print_lockmode(lkb->lkb_rqmode));
if (lkb->lkb_nodeid) {
if (lkb->lkb_nodeid != res->res_nodeid)
seq_printf(s, " Remote: %3d %08x", lkb->lkb_nodeid,
lkb->lkb_remid);
else
seq_printf(s, " Master: %08x", lkb->lkb_remid);
}
if (lkb->lkb_wait_type)
seq_printf(s, " wait_type: %d", lkb->lkb_wait_type);
seq_printf(s, "\n");
}
static int print_resource(struct dlm_rsb *res, struct seq_file *s)
{
struct dlm_lkb *lkb;
int i, lvblen = res->res_ls->ls_lvblen, recover_list, root_list;
seq_printf(s, "\nResource %p Name (len=%d) \"", res, res->res_length);
for (i = 0; i < res->res_length; i++) {
if (isprint(res->res_name[i]))
seq_printf(s, "%c", res->res_name[i]);
else
seq_printf(s, "%c", '.');
}
if (res->res_nodeid > 0)
seq_printf(s, "\" \nLocal Copy, Master is node %d\n",
res->res_nodeid);
else if (res->res_nodeid == 0)
seq_printf(s, "\" \nMaster Copy\n");
else if (res->res_nodeid == -1)
seq_printf(s, "\" \nLooking up master (lkid %x)\n",
res->res_first_lkid);
else
seq_printf(s, "\" \nInvalid master %d\n", res->res_nodeid);
/* Print the LVB: */
if (res->res_lvbptr) {
seq_printf(s, "LVB: ");
for (i = 0; i < lvblen; i++) {
if (i == lvblen / 2)
seq_printf(s, "\n ");
seq_printf(s, "%02x ",
(unsigned char) res->res_lvbptr[i]);
}
if (rsb_flag(res, RSB_VALNOTVALID))
seq_printf(s, " (INVALID)");
seq_printf(s, "\n");
}
root_list = !list_empty(&res->res_root_list);
recover_list = !list_empty(&res->res_recover_list);
if (root_list || recover_list) {
seq_printf(s, "Recovery: root %d recover %d flags %lx "
"count %d\n", root_list, recover_list,
res->res_flags, res->res_recover_locks_count);
}
/* Print the locks attached to this resource */
seq_printf(s, "Granted Queue\n");
list_for_each_entry(lkb, &res->res_grantqueue, lkb_statequeue)
print_lock(s, lkb, res);
seq_printf(s, "Conversion Queue\n");
list_for_each_entry(lkb, &res->res_convertqueue, lkb_statequeue)
print_lock(s, lkb, res);
seq_printf(s, "Waiting Queue\n");
list_for_each_entry(lkb, &res->res_waitqueue, lkb_statequeue)
print_lock(s, lkb, res);
if (list_empty(&res->res_lookup))
goto out;
seq_printf(s, "Lookup Queue\n");
list_for_each_entry(lkb, &res->res_lookup, lkb_rsb_lookup) {
seq_printf(s, "%08x %s", lkb->lkb_id,
print_lockmode(lkb->lkb_rqmode));
if (lkb->lkb_wait_type)
seq_printf(s, " wait_type: %d", lkb->lkb_wait_type);
seq_printf(s, "\n");
}
out:
return 0;
}
static int rsb_iter_next(struct rsb_iter *ri)
{
struct dlm_ls *ls = ri->ls;
int i;
if (!ri->next) {
top:
/* Find the next non-empty hash bucket */
for (i = ri->entry; i < ls->ls_rsbtbl_size; i++) {
read_lock(&ls->ls_rsbtbl[i].lock);
if (!list_empty(&ls->ls_rsbtbl[i].list)) {
ri->next = ls->ls_rsbtbl[i].list.next;
ri->rsb = list_entry(ri->next, struct dlm_rsb,
res_hashchain);
dlm_hold_rsb(ri->rsb);
read_unlock(&ls->ls_rsbtbl[i].lock);
break;
}
read_unlock(&ls->ls_rsbtbl[i].lock);
}
ri->entry = i;
if (ri->entry >= ls->ls_rsbtbl_size)
return 1;
} else {
struct dlm_rsb *old = ri->rsb;
i = ri->entry;
read_lock(&ls->ls_rsbtbl[i].lock);
ri->next = ri->next->next;
if (ri->next->next == ls->ls_rsbtbl[i].list.next) {
/* End of list - move to next bucket */
ri->next = NULL;
ri->entry++;
read_unlock(&ls->ls_rsbtbl[i].lock);
dlm_put_rsb(old);
goto top;
}
ri->rsb = list_entry(ri->next, struct dlm_rsb, res_hashchain);
read_unlock(&ls->ls_rsbtbl[i].lock);
dlm_put_rsb(old);
}
return 0;
}
static void rsb_iter_free(struct rsb_iter *ri)
{
kfree(ri);
}
static struct rsb_iter *rsb_iter_init(struct dlm_ls *ls)
{
struct rsb_iter *ri;
ri = kmalloc(sizeof *ri, GFP_KERNEL);
if (!ri)
return NULL;
ri->ls = ls;
ri->entry = 0;
ri->next = NULL;
if (rsb_iter_next(ri)) {
rsb_iter_free(ri);
return NULL;
}
return ri;
}
static void *rsb_seq_start(struct seq_file *file, loff_t *pos)
{
struct rsb_iter *ri;
loff_t n = *pos;
ri = rsb_iter_init(file->private);
if (!ri)
return NULL;
while (n--) {
if (rsb_iter_next(ri)) {
rsb_iter_free(ri);
return NULL;
}
}
return ri;
}
static void *rsb_seq_next(struct seq_file *file, void *iter_ptr, loff_t *pos)
{
struct rsb_iter *ri = iter_ptr;
(*pos)++;
if (rsb_iter_next(ri)) {
rsb_iter_free(ri);
return NULL;
}
return ri;
}
static void rsb_seq_stop(struct seq_file *file, void *iter_ptr)
{
/* nothing for now */
}
static int rsb_seq_show(struct seq_file *file, void *iter_ptr)
{
struct rsb_iter *ri = iter_ptr;
print_resource(ri->rsb, file);
return 0;
}
static struct seq_operations rsb_seq_ops = {
.start = rsb_seq_start,
.next = rsb_seq_next,
.stop = rsb_seq_stop,
.show = rsb_seq_show,
};
static int rsb_open(struct inode *inode, struct file *file)
{
struct seq_file *seq;
int ret;
ret = seq_open(file, &rsb_seq_ops);
if (ret)
return ret;
seq = file->private_data;
seq->private = inode->i_private;
return 0;
}
static const struct file_operations rsb_fops = {
.owner = THIS_MODULE,
.open = rsb_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release
};
/*
* dump lkb's on the ls_waiters list
*/
static int waiters_open(struct inode *inode, struct file *file)
{
file->private_data = inode->i_private;
return 0;
}
static ssize_t waiters_read(struct file *file, char __user *userbuf,
size_t count, loff_t *ppos)
{
struct dlm_ls *ls = file->private_data;
struct dlm_lkb *lkb;
size_t len = DLM_DEBUG_BUF_LEN, pos = 0, ret, rv;
mutex_lock(&debug_buf_lock);
mutex_lock(&ls->ls_waiters_mutex);
memset(debug_buf, 0, sizeof(debug_buf));
list_for_each_entry(lkb, &ls->ls_waiters, lkb_wait_reply) {
ret = snprintf(debug_buf + pos, len - pos, "%x %d %d %s\n",
lkb->lkb_id, lkb->lkb_wait_type,
lkb->lkb_nodeid, lkb->lkb_resource->res_name);
if (ret >= len - pos)
break;
pos += ret;
}
mutex_unlock(&ls->ls_waiters_mutex);
rv = simple_read_from_buffer(userbuf, count, ppos, debug_buf, pos);
mutex_unlock(&debug_buf_lock);
return rv;
}
static const struct file_operations waiters_fops = {
.owner = THIS_MODULE,
.open = waiters_open,
.read = waiters_read
};
int dlm_create_debug_file(struct dlm_ls *ls)
{
char name[DLM_LOCKSPACE_LEN+8];
ls->ls_debug_rsb_dentry = debugfs_create_file(ls->ls_name,
S_IFREG | S_IRUGO,
dlm_root,
ls,
&rsb_fops);
if (!ls->ls_debug_rsb_dentry)
return -ENOMEM;
memset(name, 0, sizeof(name));
snprintf(name, DLM_LOCKSPACE_LEN+8, "%s_waiters", ls->ls_name);
ls->ls_debug_waiters_dentry = debugfs_create_file(name,
S_IFREG | S_IRUGO,
dlm_root,
ls,
&waiters_fops);
if (!ls->ls_debug_waiters_dentry) {
debugfs_remove(ls->ls_debug_rsb_dentry);
return -ENOMEM;
}
return 0;
}
void dlm_delete_debug_file(struct dlm_ls *ls)
{
if (ls->ls_debug_rsb_dentry)
debugfs_remove(ls->ls_debug_rsb_dentry);
if (ls->ls_debug_waiters_dentry)
debugfs_remove(ls->ls_debug_waiters_dentry);
}
int dlm_register_debugfs(void)
{
mutex_init(&debug_buf_lock);
dlm_root = debugfs_create_dir("dlm", NULL);
return dlm_root ? 0 : -ENOMEM;
}
void dlm_unregister_debugfs(void)
{
debugfs_remove(dlm_root);
}