@@ -29,7 +29,7 @@ However, with a pretty printer gdb will output something like this:
(gdb) print mutex
$1 = pthread_mutex_t = {
Type = Normal,
- Status = Unlocked,
+ Status = Not acquired,
Robust = No,
Shared = No,
Protocol = Priority protect,
@@ -145,6 +145,11 @@ any changes to the target code must also update the corresponding printers.
On the plus side, the printer code itself may serve as a kind of documentation
for the target code.
+* There's no guarantee that the information the pretty printers provide is
+complete, i.e. some details might be left off. For example, the pthread_mutex_t
+printers won't report whether a thread is spin-waiting in an attempt to acquire
+the mutex.
+
* Older versions of the gdb Python API have a bug where
gdb.RegexpCollectionPrettyPrinter would not be able to get a value's real type
if it was typedef'd. This would cause gdb to ignore the pretty printers for
@@ -101,9 +101,9 @@ class MutexPrinter(object):
def read_status(self):
"""Read the mutex's status.
- For architectures which support lock elision, this method reads
- whether the mutex appears as locked in memory (i.e. it may show it as
- unlocked even after calling pthread_mutex_lock).
+ Architectures that support lock elision might not record the mutex owner
+ ID in the __owner field. In that case, the owner will be reported as
+ "Unknown".
"""
if self.kind == PTHREAD_MUTEX_DESTROYED:
@@ -124,13 +124,14 @@ class MutexPrinter(object):
"""
if self.lock == PTHREAD_MUTEX_UNLOCKED:
- self.values.append(('Status', 'Unlocked'))
+ self.values.append(('Status', 'Not acquired'))
else:
if self.lock & FUTEX_WAITERS:
- self.values.append(('Status', 'Locked, possibly with waiters'))
+ self.values.append(('Status',
+ 'Acquired, possibly with waiters'))
else:
self.values.append(('Status',
- 'Locked, possibly with no waiters'))
+ 'Acquired, possibly with no waiters'))
if self.lock & FUTEX_OWNER_DIED:
self.values.append(('Owner ID', '%d (dead)' % self.owner))
@@ -147,7 +148,7 @@ class MutexPrinter(object):
def read_status_no_robust(self):
"""Read the status of a non-robust mutex.
- Read info on whether the mutex is locked, if it may have waiters
+ Read info on whether the mutex is acquired, if it may have waiters
and its owner (if any).
"""
@@ -157,7 +158,7 @@ class MutexPrinter(object):
lock_value &= ~(PTHREAD_MUTEX_PRIO_CEILING_MASK)
if lock_value == PTHREAD_MUTEX_UNLOCKED:
- self.values.append(('Status', 'Unlocked'))
+ self.values.append(('Status', 'Not acquired'))
else:
if self.kind & PTHREAD_MUTEX_PRIO_INHERIT_NP:
waiters = self.lock & FUTEX_WAITERS
@@ -168,12 +169,18 @@ class MutexPrinter(object):
owner = self.owner
if waiters:
- self.values.append(('Status', 'Locked, possibly with waiters'))
+ self.values.append(('Status',
+ 'Acquired, possibly with waiters'))
else:
self.values.append(('Status',
- 'Locked, possibly with no waiters'))
+ 'Acquired, possibly with no waiters'))
- self.values.append(('Owner ID', owner))
+ if self.owner != 0:
+ self.values.append(('Owner ID', owner))
+ else:
+ # Owner isn't recorded, probably because lock elision
+ # is enabled.
+ self.values.append(('Owner ID', 'Unknown'))
def read_attributes(self):
"""Read the mutex's attributes."""
@@ -208,14 +215,14 @@ class MutexPrinter(object):
def read_misc_info(self):
"""Read miscellaneous info on the mutex.
- For now this reads the number of times a recursive mutex was locked
+ For now this reads the number of times a recursive mutex was acquired
by the same thread.
"""
mutex_type = self.kind & PTHREAD_MUTEX_KIND_MASK
if mutex_type == PTHREAD_MUTEX_RECURSIVE and self.count > 1:
- self.values.append(('Times locked recursively', self.count))
+ self.values.append(('Times acquired by the owner', self.count))
class MutexAttributesPrinter(object):
"""Pretty printer for pthread_mutexattr_t.
@@ -39,15 +39,18 @@ try:
break_at(test_source, 'Test status (non-robust)')
continue_cmd() # Go to test_status_no_robust
- test_printer(var, to_string, {'Status': 'Unlocked'})
+ test_printer(var, to_string, {'Status': 'Not acquired'})
next_cmd()
thread_id = get_current_thread_lwpid()
- test_printer(var, to_string, {'Status': 'Locked, possibly with no waiters',
- 'Owner ID': thread_id})
+ # Owner ID might be reported either as the thread ID or as "Unknown"
+ # (if e.g. lock elision is enabled).
+ test_printer(var, to_string,
+ {'Status': 'Acquired, possibly with no waiters',
+ 'Owner ID': r'({0}|Unknown)'.format(thread_id)})
break_at(test_source, 'Test status (robust)')
continue_cmd() # Go to test_status_robust
- test_printer(var, to_string, {'Status': 'Unlocked'})
+ test_printer(var, to_string, {'Status': 'Not acquired'})
# We'll now test the robust mutex locking states. We'll create a new
# thread that will lock a robust mutex and exit without unlocking it.
@@ -75,15 +78,15 @@ try:
test_printer(var, to_string, {'Owner ID': thread_id,
'State protected by this mutex': 'Inconsistent'})
next_cmd()
- test_printer(var, to_string, {'Status': 'Unlocked',
+ test_printer(var, to_string, {'Status': 'Not acquired',
'State protected by this mutex': 'Not recoverable'})
set_scheduler_locking(False)
break_at(test_source, 'Test recursive locks')
continue_cmd() # Go to test_recursive_locks
- test_printer(var, to_string, {'Times locked recursively': '2'})
+ test_printer(var, to_string, {'Times acquired by the owner': '2'})
next_cmd()
- test_printer(var, to_string, {'Times locked recursively': '3'})
+ test_printer(var, to_string, {'Times acquired by the owner': '3'})
continue_cmd() # Exit
except (NoLineError, pexpect.TIMEOUT) as exception: