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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index c9e4e50..ce8339c 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -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 @@
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))