[Cluster-devel] [PATCH] GFS2: bz 236008: Kernel gpf doing cat /debugfs/gfs2/xxx (lock dump)

[Robert Peterson <rpeterso@redhat.com>]

This is for Bugzilla Bug 236008: Kernel gpf doing cat /debugfs/gfs2/xxx 
(lock dump) seen at the "gfs2 summit".  This also fixes the bug that caused
garbage to be printed by the "initialized at" field.  I apologize for the
kludge, but that code will all be ripped out anyway when the official 
sprint_symbol function becomes available in the Linux kernel.  I also
changed some formatting so that spaces are replaced by proper tabs.
------------------------------------------------------------------------------------

Signed-off-by: Bob Peterson (rpeterso at redhat.com)

 fs/gfs2/glock.c |   29 +++++++++++++++++++++--------
 1 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index d2e3094..b075f93 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1765,15 +1765,20 @@ static void gfs2_print_symbol(struct glock_iter *gi, const char *fmt,
 {
 /* when sprint_symbol becomes available in the new kernel, replace this */
 /* function with:
-        char buffer[KSYM_SYMBOL_LEN];
+       char buffer[KSYM_SYMBOL_LEN];
 
-        sprint_symbol(buffer, address);
-        print_dbg(gi, fmt, buffer);
+       sprint_symbol(buffer, address);
+       print_dbg(gi, fmt, buffer);
 */
-        if (gi)
-                print_dbg(gi, fmt, address);
-        else
-                print_symbol(fmt, address);
+       char buffer[256];
+
+       if (gi) {
+               memset(buffer, 0, sizeof(buffer));
+               sprintf(buffer, "%p", address);
+               print_dbg(gi, fmt, buffer);
+       }
+       else
+               print_symbol(fmt, address);
 }
 
 /**
@@ -1993,14 +1998,19 @@ int __init gfs2_glock_init(void)
 
 static int gfs2_glock_iter_next(struct glock_iter *gi)
 {
+       read_lock(gl_lock_addr(gi->hash));
        while (1) {
                if (!gi->hb_list) {  /* If we don't have a hash bucket yet */
                        gi->hb_list = &gl_hash_table[gi->hash].hb_list;
                        if (hlist_empty(gi->hb_list)) {
+                               read_unlock(gl_lock_addr(gi->hash));
                                gi->hash++;
+                               read_lock(gl_lock_addr(gi->hash));
                                gi->hb_list = NULL;
-                               if (gi->hash >= GFS2_GL_HASH_SIZE)
+                               if (gi->hash >= GFS2_GL_HASH_SIZE) {
+                                       read_unlock(gl_lock_addr(gi->hash));
                                        return 1;
+                               }
                                else
                                        continue;
                        }
@@ -2011,7 +2021,9 @@ static int gfs2_glock_iter_next(struct glock_iter *gi)
                        }
                } else {
                        if (gi->gl->gl_list.next == NULL) {
+                               read_unlock(gl_lock_addr(gi->hash));
                                gi->hash++;
+                               read_lock(gl_lock_addr(gi->hash));
                                gi->hb_list = NULL;
                                continue;
                        }
@@ -2021,6 +2033,7 @@ static int gfs2_glock_iter_next(struct glock_iter *gi)
                if (gi->gl)
                        break;
        }
+       read_unlock(gl_lock_addr(gi->hash));
        return 0;
 }