Tejun Heo wrote:
> Miles Lane wrote:
>>> Thanks a lot. Just in case, if you remove the patch (patch -R -p1), the
>>> oops goes away, right?
>> I double-checked. I can boot fine after building without your patch.
>> Also, I reproduced the initial BUG I reported (triggered by
>> "modprobe -r ipw2200").
>
> This is creepy. I was able to reproduce the oops here with your
> configuration file and making buffers for kallsyms static solved the
> problem. It isn't stack overflow. At maximum those arrays added 254
> bytes to the stack and when the oops occurs stack area was left more
> than enough. I'll keep looking into why that happened but the attached
> patch should get us going on the original subject.
Alright, found out what was going on. KSYM_NAME_LEN doesn't include
space for the trailing '\0'. Gees, I've read enough assembly for the
month to find that out. Anyways, here's proper debug patch.
Thanks.
--
tejun
---
fs/sysfs/dir.c | 43 +++++++++++++++++++++++++++++++++++++++++++
fs/sysfs/sysfs.h | 16 ++--------------
include/linux/sysfs.h | 3 +++
net/core/net-sysfs.c | 6 +++++-
4 files changed, 53 insertions(+), 15 deletions(-)
Index: tree0/fs/sysfs/dir.c
===================================================================
--- tree0.orig/fs/sysfs/dir.c
+++ tree0/fs/sysfs/dir.c
@@ -11,15 +11,52 @@
#include <linux/namei.h>
#include <linux/idr.h>
#include <linux/completion.h>
+#include <linux/kallsyms.h>
#include <asm/semaphore.h>
#include "sysfs.h"
+struct kobject *sysfs_debug_me;
+
DEFINE_MUTEX(sysfs_mutex);
spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;
static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
static DEFINE_IDA(sysfs_ino_ida);
+struct sysfs_dirent * sysfs_get(struct sysfs_dirent * sd)
+{
+ if (sd) {
+ if (sd->s_flags & SYSFS_FLAG_XXX) {
+ char c0[KSYM_NAME_LEN + 1], c1[KSYM_NAME_LEN + 1];
+
+ lookup_symbol_name((unsigned long)__builtin_return_address(0), c0);
+ lookup_symbol_name((unsigned long)__builtin_return_address(1), c1);
+
+ printk("sysfs_get(%s): cnt=%d++ called from %s:%s\n",
+ sd->s_name, atomic_read(&sd->s_count), c0, c1);
+ }
+ WARN_ON(!atomic_read(&sd->s_count));
+ atomic_inc(&sd->s_count);
+ }
+ return sd;
+}
+
+void sysfs_put(struct sysfs_dirent * sd)
+{
+ if (sd && sd->s_flags & SYSFS_FLAG_XXX) {
+ char c0[KSYM_NAME_LEN + 1], c1[KSYM_NAME_LEN + 1];
+
+ lookup_symbol_name((unsigned long)__builtin_return_address(0), c0);
+ lookup_symbol_name((unsigned long)__builtin_return_address(1), c1);
+
+ printk("sysfs_put(%s): cnt=%d-- called from %s:%s\n",
+ sd->s_name, atomic_read(&sd->s_count), c0, c1);
+ }
+
+ if (sd && atomic_dec_and_test(&sd->s_count))
+ release_sysfs_dirent(sd);
+}
+
/**
* sysfs_link_sibling - link sysfs_dirent into sibling list
* @sd: sysfs_dirent of interest
@@ -317,6 +354,10 @@ void release_sysfs_dirent(struct sysfs_d
* sd->s_parent won't change beneath us.
*/
parent_sd = sd->s_parent;
+ if (parent_sd->s_flags & SYSFS_FLAG_XXX)
+ printk("put from release(%s): cnt=%d-- (rel=%s)\n",
+ parent_sd->s_name, atomic_read(&parent_sd->s_count),
+ sd->s_name);
if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
sysfs_put(sd->s_elem.symlink.target_sd);
@@ -695,6 +736,8 @@ static int create_dir(struct kobject *ko
if (!sd)
return -ENOMEM;
sd->s_elem.dir.kobj = kobj;
+ if (sysfs_debug_me && sysfs_debug_me == kobj)
+ sd->s_flags |= SYSFS_FLAG_XXX;
/* link in */
sysfs_addrm_start(&acxt, parent_sd);
Index: tree0/fs/sysfs/sysfs.h
===================================================================
--- tree0.orig/fs/sysfs/sysfs.h
+++ tree0/fs/sysfs/sysfs.h
@@ -108,20 +108,8 @@ static inline unsigned int sysfs_type(st
return sd->s_flags & SYSFS_TYPE_MASK;
}
-static inline struct sysfs_dirent * sysfs_get(struct sysfs_dirent * sd)
-{
- if (sd) {
- WARN_ON(!atomic_read(&sd->s_count));
- atomic_inc(&sd->s_count);
- }
- return sd;
-}
-
-static inline void sysfs_put(struct sysfs_dirent * sd)
-{
- if (sd && atomic_dec_and_test(&sd->s_count))
- release_sysfs_dirent(sd);
-}
+struct sysfs_dirent * sysfs_get(struct sysfs_dirent * sd);
+void sysfs_put(struct sysfs_dirent * sd);
static inline int sysfs_is_shadowed_inode(struct inode *inode)
{
Index: tree0/include/linux/sysfs.h
===================================================================
--- tree0.orig/include/linux/sysfs.h
+++ tree0/include/linux/sysfs.h
@@ -87,9 +87,12 @@ struct sysfs_ops {
#define SYSFS_FLAG_MASK ~SYSFS_TYPE_MASK
#define SYSFS_FLAG_REMOVED 0x0100
+#define SYSFS_FLAG_XXX 0x0200
#ifdef CONFIG_SYSFS
+extern struct kobject *sysfs_debug_me;
+
extern int sysfs_schedule_callback(struct kobject *kobj,
void (*func)(void *), void *data, struct module *owner);
Index: tree0/net/core/net-sysfs.c
===================================================================
--- tree0.orig/net/core/net-sysfs.c
+++ tree0/net/core/net-sysfs.c
@@ -472,6 +472,7 @@ int netdev_register_sysfs(struct net_dev
{
struct device *dev = &(net->dev);
struct attribute_group **groups = net->sysfs_groups;
+ int rc;
device_initialize(dev);
dev->class = &net_class;
@@ -489,7 +490,10 @@ int netdev_register_sysfs(struct net_dev
*groups++ = &wireless_group;
#endif
- return device_add(dev);
+ sysfs_debug_me = &dev->kobj;
+ rc = device_add(dev);
+ sysfs_debug_me = NULL;
+ return rc;
}
int netdev_sysfs_init(void)
