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sysfs: crash debugging

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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>
This commit is contained in:
Andrew Morton 2007-08-24 16:11:54 -07:00 committed by Greg Kroah-Hartman
parent e94320939f
commit ae87221d3c
4 changed files with 23 additions and 0 deletions
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2
arch/x86/kernel/dumpstack_32.c
View file

@ -13,6 +13,7 @@
#include <linux/kexec.h>
#include <linux/bug.h>
#include <linux/nmi.h>
#include <linux/sysfs.h>
#include <asm/stacktrace.h>
@ -343,6 +344,7 @@ int __kprobes __die(const char *str, struct pt_regs *regs, long err)
printk("DEBUG_PAGEALLOC");
#endif
printk("\n");
sysfs_printk_last_file();
if (notify_die(DIE_OOPS, str, regs, err,
current->thread.trap_no, SIGSEGV) == NOTIFY_STOP)
return 1;

2
arch/x86/kernel/dumpstack_64.c
View file

@ -13,6 +13,7 @@
#include <linux/kexec.h>
#include <linux/bug.h>
#include <linux/nmi.h>
#include <linux/sysfs.h>
#include <asm/stacktrace.h>
@ -489,6 +490,7 @@ int __kprobes __die(const char *str, struct pt_regs *regs, long err)
printk("DEBUG_PAGEALLOC");
#endif
printk("\n");
sysfs_printk_last_file();
if (notify_die(DIE_OOPS, str, regs, err,
current->thread.trap_no, SIGSEGV) == NOTIFY_STOP)
return 1;

13
fs/sysfs/file.c
View file

@ -19,10 +19,18 @@
#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
@ -328,6 +336,11 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
struct sysfs_buffer *buffer;
struct sysfs_ops *ops;
int error = -EACCES;
char *p;
p = d_path(&file->f_path, 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))

6
include/linux/sysfs.h
View file

@ -119,6 +119,8 @@ void sysfs_remove_file_from_group(struct kobject *kobj,
void sysfs_notify(struct kobject *kobj, char *dir, char *attr);
void sysfs_printk_last_file(void);
extern int __must_check sysfs_init(void);
#else /* CONFIG_SYSFS */
@ -231,6 +233,10 @@ static inline int __must_check sysfs_init(void)
return 0;
}
static inline void sysfs_printk_last_file(void)
{
}
#endif /* CONFIG_SYSFS */
#endif /* _SYSFS_H_ */