From: Heather McIntyre <h...@rice.edu>
* (try_split_file): Use eu_tsearch.
Add lock for cu->split.
Signed-off-by: Heather S. McIntyre <h...@rice.edu>
Signed-off-by: Mark Wielaard <m...@klomp.org>
---
libdw/libdw_find_split_unit.c | 43 +++++++++++++++++++++++++++++------
1 file changed, 36 insertions(+), 7 deletions(-)
diff --git a/libdw/libdw_find_split_unit.c b/libdw/libdw_find_split_unit.c
index 533f8072..a288e9bd 100644
--- a/libdw/libdw_find_split_unit.c
+++ b/libdw/libdw_find_split_unit.c
@@ -34,13 +34,19 @@
#include "libelfP.h"
#include <limits.h>
-#include <search.h>
+#include <eu-search.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
+/* __libdw_link_skel_split() modifies "skel->split = split"
+ and "split->split = skel".
+ "cu->split" is read at multiple locations and conditionally updated.
+ Mutual exclusion is enforced to prevent a race. */
+rwlock_define(static, cu_split_lock);
+
static void
try_split_file (Dwarf_CU *cu, const char *dwo_path)
{
@@ -57,7 +63,7 @@ try_split_file (Dwarf_CU *cu, const char *dwo_path)
if (split->unit_type == DW_UT_split_compile
&& cu->unit_id8 == split->unit_id8)
{
- if (tsearch (split->dbg, &cu->dbg->split_tree,
+ if (eu_tsearch (split->dbg, &cu->dbg->split_tree,
__libdw_finddbg_cb) == NULL)
{
/* Something went wrong. Don't link. */
@@ -65,9 +71,13 @@ try_split_file (Dwarf_CU *cu, const char *dwo_path)
break;
}
+ rwlock_wrlock(cu_split_lock);
+
/* Link skeleton and split compile units. */
__libdw_link_skel_split (cu, split);
+ rwlock_unlock(cu_split_lock);
+
/* We have everything we need from this ELF
file. And we are going to close the fd to
not run out of file descriptors. */
@@ -75,8 +85,13 @@ try_split_file (Dwarf_CU *cu, const char *dwo_path)
break;
}
}
+
+ rwlock_rdlock(cu_split_lock);
+
if (cu->split == (Dwarf_CU *) -1)
dwarf_end (split_dwarf);
+
+ rwlock_unlock(cu_split_lock);
}
/* Always close, because we don't want to run out of file
descriptors. See also the elf_fcntl ELF_C_FDDONE call
@@ -89,9 +104,13 @@ Dwarf_CU *
internal_function
__libdw_find_split_unit (Dwarf_CU *cu)
{
+ rwlock_rdlock(cu_split_lock);
+ Dwarf_CU *cu_split_local = cu->split;
+ rwlock_unlock(cu_split_lock);
+
/* Only try once. */
- if (cu->split != (Dwarf_CU *) -1)
- return cu->split;
+ if (cu_split_local != (Dwarf_CU *) -1)
+ return cu_split_local;
/* We need a skeleton unit with a comp_dir and [GNU_]dwo_name attributes.
The split unit will be the first in the dwo file and should have the
@@ -116,7 +135,11 @@ __libdw_find_split_unit (Dwarf_CU *cu)
free (dwo_path);
}
- if (cu->split == (Dwarf_CU *) -1)
+ rwlock_rdlock(cu_split_lock);
+ cu_split_local = cu->split;
+ rwlock_unlock(cu_split_lock);
+
+ if (cu_split_local == (Dwarf_CU *) -1)
{
/* Try compdir plus dwo_name. */
Dwarf_Attribute compdir;
@@ -138,9 +161,15 @@ __libdw_find_split_unit (Dwarf_CU *cu)
}
}
+ rwlock_wrlock(cu_split_lock);
+
/* If we found nothing, make sure we don't try again. */
if (cu->split == (Dwarf_CU *) -1)
- cu->split = NULL;
+ {
+ cu->split = NULL;
+ cu_split_local = cu->split;
+ }
- return cu->split;
+ rwlock_unlock(cu_split_lock);
+ return cu_split_local;
}
--
2.41.0
