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From akpm@linux-foundation.org Fri Aug 24 16:12:31 2007
From: Andrew Morton <akpm@linux-foundation.org>
Date: Fri, 24 Aug 2007 16:11:54 -0700
Subject: sysfs: crash debugging
To: mm-commits@vger.kernel.org
Cc: akpm@linux-foundation.org, greg@kroah.com, kay.sievers@vrfy.org, mathieu.desnoyers@polymtl.ca
Message-ID: <200708242311.l7ONBsvq019579@imap1.linux-foundation.org>
Print the name of the last-accessed sysfs file when we oops, to help track
down oopses which occur in sysfs store/read handlers. Because these oopses
tend to not leave any trace of the offending code in the stack traces.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
arch/x86/kernel/traps_32.c | 1 +
arch/x86/kernel/traps_64.c | 1 +
fs/sysfs/file.c | 14 ++++++++++++++
fs/sysfs/mount.c | 2 +-
fs/sysfs/sysfs.h | 1 +
include/linux/sysfs.h | 5 +++++
6 files changed, 23 insertions(+), 1 deletion(-)
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -396,6 +396,7 @@ void die(const char * str, struct pt_reg
#endif
printk("\n");
+ sysfs_printk_last_file();
if (notify_die(DIE_OOPS, str, regs, err,
current->thread.trap_no, SIGSEGV) !=
NOTIFY_STOP) {
--- a/arch/x86/kernel/traps_64.c
+++ b/arch/x86/kernel/traps_64.c
@@ -517,6 +517,7 @@ void __kprobes __die(const char * str, s
printk("DEBUG_PAGEALLOC");
#endif
printk("\n");
+ sysfs_printk_last_file();
notify_die(DIE_OOPS, str, regs, err, current->thread.trap_no, SIGSEGV);
show_registers(regs);
add_taint(TAINT_DIE);
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -16,10 +16,18 @@
#include <linux/poll.h>
#include <linux/list.h>
#include <linux/mutex.h>
+#include <linux/limits.h>
#include <asm/uaccess.h>
#include "sysfs.h"
+/* used in crash dumps to help with debugging */
+static char last_sysfs_file[PATH_MAX];
+void sysfs_printk_last_file(void)
+{
+ printk(KERN_EMERG "last sysfs file: %s\n", last_sysfs_file);
+}
+
/*
* There's one sysfs_buffer for each open file and one
* sysfs_open_dirent for each sysfs_dirent with one or more open
@@ -316,6 +324,12 @@ static int sysfs_open_file(struct inode
struct sysfs_buffer *buffer;
struct sysfs_ops *ops;
int error = -EACCES;
+ char *p;
+
+ p = d_path(file->f_dentry, sysfs_mount, last_sysfs_file,
+ sizeof(last_sysfs_file));
+ if (p)
+ memmove(last_sysfs_file, p, strlen(p) + 1);
/* need attr_sd for attr and ops, its parent for kobj */
if (!sysfs_get_active_two(attr_sd))
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -22,7 +22,7 @@
/* Random magic number */
#define SYSFS_MAGIC 0x62656572
-static struct vfsmount *sysfs_mount;
+struct vfsmount *sysfs_mount;
struct super_block * sysfs_sb = NULL;
struct kmem_cache *sysfs_dir_cachep;
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -91,6 +91,7 @@ struct sysfs_addrm_cxt {
extern struct sysfs_dirent sysfs_root;
extern struct super_block *sysfs_sb;
extern struct kmem_cache *sysfs_dir_cachep;
+extern struct vfsmount *sysfs_mount;
/*
* dir.c
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -111,6 +111,7 @@ void sysfs_remove_file_from_group(struct
const struct attribute *attr, const char *group);
void sysfs_notify(struct kobject *kobj, char *dir, char *attr);
+void sysfs_printk_last_file(void);
extern int __must_check sysfs_init(void);
@@ -216,6 +217,10 @@ static inline int __must_check sysfs_ini
return 0;
}
+static inline void sysfs_printk_last_file(void)
+{
+}
+
#endif /* CONFIG_SYSFS */
#endif /* _SYSFS_H_ */
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