From: Mark Wielaard <mark@klomp.org>
To: elfutils-devel@sourceware.org
Cc: hsm2@rice.edu, Mark Wielaard <mark@klomp.org>
Subject: [PATCH 10/16] libdw: make dwarf_getalt thread-safe
Date: Tue, 10 Oct 2023 15:42:54 +0200 [thread overview]
Message-ID: <20231010134300.53830-10-mark@klomp.org> (raw)
In-Reply-To: <20231010134300.53830-1-mark@klomp.org>
From: Heather McIntyre <hsm2@rice.edu>
* libdw/dwarf_getalt.c: Add lock for
dbg->alt_dwarf/main->alt_dwarf.
Signed-off-by: Heather S. McIntyre <hsm2@rice.edu>
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
libdw/dwarf_getalt.c | 27 ++++++++++++++++++++++-----
1 file changed, 22 insertions(+), 5 deletions(-)
diff --git a/libdw/dwarf_getalt.c b/libdw/dwarf_getalt.c
index 0a12dfae..e3894c8c 100644
--- a/libdw/dwarf_getalt.c
+++ b/libdw/dwarf_getalt.c
@@ -44,6 +44,10 @@
#include <sys/types.h>
#include <sys/stat.h>
+/* find_debug_altlink() modifies "dbg->alt_dwarf".
+ dwarf_getalt() reads "main->alt_dwarf".
+ Mutual exclusion is enforced to prevent a race. */
+rwlock_define(static, alt_dwarf_lock);
char *
internal_function
@@ -152,7 +156,9 @@ find_debug_altlink (Dwarf *dbg)
Dwarf *alt = dwarf_begin (fd, O_RDONLY);
if (alt != NULL)
{
+ rwlock_wrlock(alt_dwarf_lock);
dbg->alt_dwarf = alt;
+ rwlock_unlock(alt_dwarf_lock);
dbg->alt_fd = fd;
}
else
@@ -163,22 +169,33 @@ find_debug_altlink (Dwarf *dbg)
Dwarf *
dwarf_getalt (Dwarf *main)
{
+ rwlock_rdlock(alt_dwarf_lock);
+ Dwarf *alt_dwarf_local = main->alt_dwarf;
+ rwlock_unlock(alt_dwarf_lock);
+
/* Only try once. */
- if (main == NULL || main->alt_dwarf == (void *) -1)
+ if (main == NULL || alt_dwarf_local == (void *) -1)
return NULL;
- if (main->alt_dwarf != NULL)
- return main->alt_dwarf;
+ if (alt_dwarf_local != NULL)
+ return alt_dwarf_local;
find_debug_altlink (main);
+ rwlock_rdlock(alt_dwarf_lock);
+ alt_dwarf_local = main->alt_dwarf;
+ rwlock_unlock(alt_dwarf_lock);
+
/* If we found nothing, make sure we don't try again. */
- if (main->alt_dwarf == NULL)
+ if (alt_dwarf_local == NULL)
{
+ rwlock_wrlock(alt_dwarf_lock);
main->alt_dwarf = (void *) -1;
+ rwlock_unlock(alt_dwarf_lock);
+
return NULL;
}
- return main->alt_dwarf;
+ return alt_dwarf_local;
}
INTDEF (dwarf_getalt)
--
2.41.0
next prev parent reply other threads:[~2023-10-10 13:43 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-08 17:07 [PATCH] Fix thread-safety for elfutils Heather McIntyre
2023-08-21 22:08 ` John Mellor-Crummey
2023-08-25 14:10 ` Mark Wielaard
2023-10-10 13:40 ` Mark Wielaard
2023-10-10 13:42 ` [PATCH 01/16] lib: Add new once_define and once macros to eu-config.h Mark Wielaard
2023-10-10 13:42 ` [PATCH 02/16] libelf: Make elf_version thread-safe Mark Wielaard
2023-10-10 14:00 ` Mark Wielaard
2023-10-17 19:05 ` Heather McIntyre
2023-10-19 21:00 ` Mark Wielaard
2023-10-10 13:42 ` [PATCH 03/16] libelf: Fix deadlock in __libelf_readall Mark Wielaard
2023-10-10 15:06 ` Mark Wielaard
2023-10-17 19:11 ` Heather McIntyre
2023-11-09 13:26 ` Mark Wielaard
2023-10-10 13:42 ` [PATCH 04/16] libelf: Fix deadlock in elf_cntl Mark Wielaard
2023-10-10 15:23 ` Mark Wielaard
2023-10-17 19:14 ` Heather McIntyre
2023-10-10 13:42 ` [PATCH 05/16] libelf: Fix elf_end deadlock Mark Wielaard
2023-10-10 15:28 ` Mark Wielaard
2023-10-10 13:42 ` [PATCH 06/16] libelf: Make elf32_getchdr and elf64_getchdr thread-safe Mark Wielaard
2023-10-10 16:28 ` Mark Wielaard
2023-10-10 13:42 ` [PATCH 07/16] lib: Add eu_tsearch and eu_tfind Mark Wielaard
2023-10-10 16:51 ` Mark Wielaard
2023-10-17 20:52 ` Heather McIntyre
2023-10-10 13:42 ` [PATCH 08/16] libcpu: Change calls for tsearch/tfind to eu_tsearch/eu_tfind Mark Wielaard
2023-10-10 21:10 ` Mark Wielaard
2023-10-10 13:42 ` [PATCH 09/16] src: Use eu-search in nm and findtextrel Mark Wielaard
2023-10-10 21:25 ` Mark Wielaard
2023-10-17 19:20 ` Heather McIntyre
2023-10-10 13:42 ` Mark Wielaard [this message]
2023-10-10 22:02 ` [PATCH 10/16] libdw: make dwarf_getalt thread-safe Mark Wielaard
2023-10-17 19:25 ` Heather McIntyre
2023-10-10 13:42 ` [PATCH 11/16] libdw: Add locking around __libdw_dieabbrev for dwarf_hasattr Mark Wielaard
2023-10-11 15:10 ` Mark Wielaard
2023-10-17 19:57 ` Heather McIntyre
2023-10-19 22:06 ` Mark Wielaard
2023-10-10 13:42 ` [PATCH 12/16] libdw: Make libdw_find_split_unit thread-safe Mark Wielaard
2023-10-11 17:17 ` Mark Wielaard
2023-10-17 20:01 ` Heather McIntyre
2023-10-10 13:42 ` [PATCH 13/16] libdw: Make libdw_findcu thread-safe Mark Wielaard
2023-10-12 22:02 ` Mark Wielaard
2023-10-17 20:10 ` Heather McIntyre
2023-10-10 13:42 ` [PATCH 14/16] libdw,libdwfl: Use eu-search for thread-safety Mark Wielaard
2023-10-12 22:05 ` Mark Wielaard
2023-10-10 13:42 ` [PATCH 15/16] tests: Add eu-search tests Mark Wielaard
2023-10-13 14:38 ` Mark Wielaard
2023-10-10 13:43 ` [PATCH 16/16] configure: No longer mark --enable-thread-safety as EXPERIMENTAL Mark Wielaard
2023-10-12 22:09 ` Mark Wielaard
2023-10-10 13:54 ` [PATCH 01/16] lib: Add new once_define and once macros to eu-config.h Mark Wielaard
2023-10-14 15:39 ` [PATCH] Fix thread-safety for elfutils Mark Wielaard
2023-10-14 18:29 ` Heather McIntyre
2023-10-17 15:04 ` Mark Wielaard
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