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Commit ae87221d authored by Andrew Morton's avatar Andrew Morton Committed by Greg Kroah-Hartman
Browse files

sysfs: crash debugging 



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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent e9432093

arch/x86/kernel/dumpstack_32.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/kernel/dumpstack_64.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

fs/sysfs/file.c

+13 −0
Original line number Diff line number Diff line
@@ -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))

include/linux/sysfs.h

+6 −0
Original line number Diff line number Diff line
@@ -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_ */