if blktrace program segfault it will not be able
to call BLKTRACETEARDOWN. Now if we run the blktrace
again that would result in a failure to create the
block/<device> debugfs directory.This will result
in blk_remove_root() to be called which will set
blk_tree_root to NULL. But the debugfs block dir
still exist because it contain subdirectory.
Now if we try to fix it using BLKTRACETEARDOWN
it won't work because blk_tree_root is NULL.
Fix the same.
Tested as below
root@qemu-image:/home/kvaneesh/blktrace# ./blktrace -d /dev/hdc
Segmentation fault
root@qemu-image:/home/kvaneesh/blktrace# ./blktrace -d /dev/hdc
BLKTRACESETUP: No such file or directory
Failed to start trace on /dev/hdc
root@qemu-image:/home/kvaneesh/blktrace# ./blktrace -k /dev/hdc
root@qemu-image:/home/kvaneesh/blktrace# ./blktrace -d /dev/hdc
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
block/blktrace.c | 9 +++++++--
1 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/block/blktrace.c b/block/blktrace.c
index d00ac39..498a0a5 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -202,6 +202,7 @@ static void blk_remove_tree(struct dentry *dir)
static struct dentry *blk_create_tree(const char *blk_name)
{
struct dentry *dir = NULL;
+ int created = 0;
mutex_lock(&blk_tree_mutex);
@@ -209,13 +210,17 @@ static struct dentry *blk_create_tree(const char *blk_name)
blk_tree_root = debugfs_create_dir("block", NULL);
if (!blk_tree_root)
goto err;
+ created = 1;
}
dir = debugfs_create_dir(blk_name, blk_tree_root);
if (dir)
root_users++;
- else
- blk_remove_root();
+ else {
+ /* Delete root only if we created it */
+ if (created)
+ blk_remove_root();
+ }
err:
mutex_unlock(&blk_tree_mutex);
--
1.5.3.4.383.gd90a7-dirty
-
To unsubscribe from this list: send the line "unsubscribe linux-btrace" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
