erofs: fix up erofs_lookup tracepoint

BugLink: https://bugs.launchpad.net/bugs/1949640
commit 93368aab0efc87288cac65e99c9ed2e0ffc9e7d0 upstream.

Fix up a misuse that the filename pointer isn't always valid in
the ring buffer, and we should copy the content instead.

Link: https://lore.kernel.org/r/20210921143531.81356-1-hsiangkao@linux.alibaba.com
Fixes: 13f06f48f7bf ("staging: erofs: support tracepoint")
Cc: stable@vger.kernel.org # 4.19+
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/include/trace/events/erofs.h b/include/trace/events/erofs.h
index bf9806fd1306547e8ac6bc6bec6df71dfd8c5d14..db4f2cec8360629e5d7d19b6208b13a86e4c271c 100644 (file)
--- a/include/trace/events/erofs.h
+++ b/include/trace/events/erofs.h
@@ -35,20 +35,20 @@ TRACE_EVENT(erofs_lookup,
        TP_STRUCT__entry(
                __field(dev_t,          dev     )
                __field(erofs_nid_t,    nid     )
-               __field(const char *,   name    )
+               __string(name,          dentry->d_name.name     )
                __field(unsigned int,   flags   )
        ),
 
        TP_fast_assign(
                __entry->dev    = dir->i_sb->s_dev;
                __entry->nid    = EROFS_I(dir)->nid;
-               __entry->name   = dentry->d_name.name;
+               __assign_str(name, dentry->d_name.name);
                __entry->flags  = flags;
        ),
 
        TP_printk("dev = (%d,%d), pnid = %llu, name:%s, flags:%x",
                show_dev_nid(__entry),
-               __entry->name,
+               __get_str(name),
                __entry->flags)
 );