[PATCH 01/10 v2] Change type of dwarf_lock from rwlock to mutex
Aaron Merey
amerey@redhat.com
Tue Feb 4 21:50:39 GMT 2025
Change type of dwarf_lock to mutex in order to take advantage of
built-in support for recursive locking.
* lib/locks.h: Add macros for locking, unlocking, initializing
and destroying mutexes.
* libdw/dwarf_begin_elf.c (dwarf_end): Replace rwlock macro with
mutex macro.
* libdw/dwarf_end.c (dwarf_end): Ditto.
* libdw/dwarf_formref_die.c (dwarf_formref_die): Ditto.
* libdw/dwarf_getalt.c (dwarf_getalt): Ditto.
* libdw/dwarf_setalt.c (dwarf_setalt): Ditto.
* libdw/libdwP.h (struct Dwarf): Ditto.
* libdw/libdw_findcu.c (__libdw_findcu): Ditto.
Signed-off-by: Aaron Merey <amerey@redhat.com>
---
v2 changes: Add comments to libdwP.h locks describing which functions
they're intended to cover.
lib/locks.h | 16 ++++++++++++++++
libdw/dwarf_begin_elf.c | 2 +-
libdw/dwarf_end.c | 2 +-
libdw/dwarf_formref_die.c | 4 ++--
libdw/dwarf_getalt.c | 10 +++++-----
libdw/dwarf_setalt.c | 4 ++--
libdw/libdwP.h | 12 +++++++-----
libdw/libdw_findcu.c | 4 ++--
8 files changed, 36 insertions(+), 18 deletions(-)
diff --git a/lib/locks.h b/lib/locks.h
index 90fe3f1b..9c17eca7 100644
--- a/lib/locks.h
+++ b/lib/locks.h
@@ -43,6 +43,17 @@
# define rwlock_rdlock(lock) RWLOCK_CALL (rdlock (&lock))
# define rwlock_wrlock(lock) RWLOCK_CALL (wrlock (&lock))
# define rwlock_unlock(lock) RWLOCK_CALL (unlock (&lock))
+# define mutex_define(class,name) class pthread_mutex_t name
+# define MUTEX_CALL(call) \
+ ({ int _err = pthread_mutex_ ## call; assert_perror (_err); })
+# define mutex_init(lock) \
+ ({ pthread_mutexattr_t _attr; \
+ pthread_mutexattr_init (&_attr); \
+ pthread_mutexattr_settype (&_attr, PTHREAD_MUTEX_RECURSIVE); \
+ MUTEX_CALL (init (&lock, &_attr)); })
+# define mutex_lock(_lock) MUTEX_CALL (lock (&_lock))
+# define mutex_unlock(lock) MUTEX_CALL (unlock (&lock))
+# define mutex_fini(lock) MUTEX_CALL (destroy (&lock))
# define once(once_control, init_routine) \
ONCE_CALL (once (&once_control, init_routine))
#else
@@ -55,6 +66,11 @@
# define rwlock_rdlock(lock) ((void) (lock))
# define rwlock_wrlock(lock) ((void) (lock))
# define rwlock_unlock(lock) ((void) (lock))
+# define mutex_define(class,name) class int name
+# define mutex_init(lock) ((void) (lock))
+# define mutex_lock(lock) ((void) (lock))
+# define mutex_unlock(lock) ((void) (lock))
+# define mutex_fini(lock) ((void) (lock))
# define once_define(class,name)
# define once(once_control, init_routine) init_routine()
#endif /* USE_LOCKS */
diff --git a/libdw/dwarf_begin_elf.c b/libdw/dwarf_begin_elf.c
index c8292913..8a3a939b 100644
--- a/libdw/dwarf_begin_elf.c
+++ b/libdw/dwarf_begin_elf.c
@@ -579,7 +579,7 @@ dwarf_begin_elf (Elf *elf, Dwarf_Cmd cmd, Elf_Scn *scngrp)
__libdw_seterrno (DWARF_E_NOMEM); /* no memory. */
return NULL;
}
- rwlock_init (result->dwarf_lock);
+ mutex_init (result->dwarf_lock);
eu_search_tree_init (&result->cu_tree);
eu_search_tree_init (&result->tu_tree);
eu_search_tree_init (&result->split_tree);
diff --git a/libdw/dwarf_end.c b/libdw/dwarf_end.c
index ee3ed74e..92389c07 100644
--- a/libdw/dwarf_end.c
+++ b/libdw/dwarf_end.c
@@ -129,7 +129,7 @@ dwarf_end (Dwarf *dwarf)
if (dwarf->mem_tails != NULL)
free (dwarf->mem_tails);
pthread_rwlock_destroy (&dwarf->mem_rwl);
- rwlock_fini (dwarf->dwarf_lock);
+ mutex_fini (dwarf->dwarf_lock);
/* Free the pubnames helper structure. */
free (dwarf->pubnames_sets);
diff --git a/libdw/dwarf_formref_die.c b/libdw/dwarf_formref_die.c
index 69d1bf1c..85c484f6 100644
--- a/libdw/dwarf_formref_die.c
+++ b/libdw/dwarf_formref_die.c
@@ -92,9 +92,9 @@ dwarf_formref_die (Dwarf_Attribute *attr, Dwarf_Die *result)
bool scan_debug_types = false;
do
{
- rwlock_wrlock(attr->cu->dbg->dwarf_lock);
+ mutex_lock (attr->cu->dbg->dwarf_lock);
cu = __libdw_intern_next_unit (attr->cu->dbg, scan_debug_types);
- rwlock_unlock(attr->cu->dbg->dwarf_lock);
+ mutex_unlock (attr->cu->dbg->dwarf_lock);
if (cu == NULL)
{
diff --git a/libdw/dwarf_getalt.c b/libdw/dwarf_getalt.c
index 26433b81..f4b8ad02 100644
--- a/libdw/dwarf_getalt.c
+++ b/libdw/dwarf_getalt.c
@@ -170,12 +170,12 @@ dwarf_getalt (Dwarf *main)
if (main == NULL)
return NULL;
- rwlock_wrlock(main->dwarf_lock);
+ mutex_lock (main->dwarf_lock);
/* Only try once. */
if (main->alt_dwarf == (void *) -1)
{
- rwlock_unlock (main->dwarf_lock);
+ mutex_unlock (main->dwarf_lock);
return NULL;
}
@@ -185,7 +185,7 @@ dwarf_getalt (Dwarf *main)
if (main->alt_dwarf != NULL)
{
result = main->alt_dwarf;
- rwlock_unlock (main->dwarf_lock);
+ mutex_unlock (main->dwarf_lock);
return result;
}
@@ -195,12 +195,12 @@ dwarf_getalt (Dwarf *main)
if (main->alt_dwarf == NULL)
{
main->alt_dwarf = (void *) -1;
- rwlock_unlock (main->dwarf_lock);
+ mutex_unlock (main->dwarf_lock);
return NULL;
}
result = main->alt_dwarf;
- rwlock_unlock (main->dwarf_lock);
+ mutex_unlock (main->dwarf_lock);
return result;
}
diff --git a/libdw/dwarf_setalt.c b/libdw/dwarf_setalt.c
index f98a457c..d8790fd3 100644
--- a/libdw/dwarf_setalt.c
+++ b/libdw/dwarf_setalt.c
@@ -35,7 +35,7 @@
void
dwarf_setalt (Dwarf *main, Dwarf *alt)
{
- rwlock_wrlock (main->dwarf_lock);
+ mutex_lock (main->dwarf_lock);
if (main->alt_fd != -1)
{
@@ -45,6 +45,6 @@ dwarf_setalt (Dwarf *main, Dwarf *alt)
}
main->alt_dwarf = alt;
- rwlock_unlock (main->dwarf_lock);
+ mutex_unlock (main->dwarf_lock);
}
INTDEF (dwarf_setalt)
diff --git a/libdw/libdwP.h b/libdw/libdwP.h
index d6bab606..9d2ffab0 100644
--- a/libdw/libdwP.h
+++ b/libdw/libdwP.h
@@ -264,9 +264,10 @@ struct Dwarf
allocations for this Dwarf. */
pthread_rwlock_t mem_rwl;
- /* The dwarf_lock is a read-write lock designed to ensure thread-safe access
- and modification of an entire Dwarf object. */
- rwlock_define(, dwarf_lock);
+ /* Recursive mutex intended for all libdw functions which require locking,
+ except for functions covered by rwlocks (see rwlock declarations for
+ details). */
+ mutex_define(, dwarf_lock);
/* Internal memory handling. This is basically a simplified thread-local
reimplementation of obstacks. Unfortunately the standard obstack
@@ -452,10 +453,11 @@ struct Dwarf_CU
Dwarf_Off locs_base;
/* Synchronize access to the abbrev member of a Dwarf_Die that
- refers to this Dwarf_CU. */
+ refers to this Dwarf_CU. Covers __libdw_die_abbrev. */
rwlock_define(, abbrev_lock);
- /* Synchronize access to the split member of this Dwarf_CU. */
+ /* Synchronize access to the split member of this Dwarf_CU.
+ Covers __libdw_find_split_unit. */
rwlock_define(, split_lock);
/* Memory boundaries of this CU. */
diff --git a/libdw/libdw_findcu.c b/libdw/libdw_findcu.c
index bbbbee5d..613f61c8 100644
--- a/libdw/libdw_findcu.c
+++ b/libdw/libdw_findcu.c
@@ -249,7 +249,7 @@ __libdw_findcu (Dwarf *dbg, Dwarf_Off start, bool v4_debug_types)
if (found != NULL)
return *found;
- rwlock_wrlock (dbg->dwarf_lock);
+ mutex_lock (dbg->dwarf_lock);
if (start < *next_offset)
__libdw_seterrno (DWARF_E_INVALID_DWARF);
@@ -276,7 +276,7 @@ __libdw_findcu (Dwarf *dbg, Dwarf_Off start, bool v4_debug_types)
}
}
- rwlock_unlock (dbg->dwarf_lock);
+ mutex_unlock (dbg->dwarf_lock);
return result;
}
--
2.48.1
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