y2038: nptl: Convert pthread_cond_{clock|timed}wait to support 64 bit time

Message ID 20200812133014.25766-1-lukma@denx.de
State New
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Series
  • y2038: nptl: Convert pthread_cond_{clock|timed}wait to support 64 bit time
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Commit Message

Lukasz Majewski Aug. 12, 2020, 1:30 p.m.
The pthread_cond_clockwait and pthread_cond_timedwait have been converted to
support 64 bit time.

This change introduces new futex_abstimed_wait_cancelable64 function in
./sysdeps/nptl/futex-internal.h, which uses futex_time64 where possible
and tries to replace low-level preprocessor macros from
lowlevellock-futex.h
The pthread_cond_{clock|timed}wait only accept absolute time. Moreover,
there is no need to check for NULL passed as *abstime pointer as
__pthread_cond_wait_common() always passes non-NULL struct __timespec64 pointer
to futex_abstimed_wait_cancellable64().

For systems with __TIMESIZE != 64 && __WORDSIZE == 32:
- Conversions between 64 bit time to 32 bit are necessary
- Redirection to __pthread_cond_{clock|timed}wait64 will provide support
  for 64 bit time

Build tests:
./src/scripts/build-many-glibcs.py glibcs

Run-time tests:
- Run specific tests on ARM/x86 32bit systems (qemu):
  https://github.com/lmajewski/meta-y2038 and run tests:
  https://github.com/lmajewski/y2038-tests/commits/master

Above tests were performed with Y2038 redirection applied as well as without
to test the proper usage of both __pthread_cond_{clock|timed}wait64 and
__pthread_cond_{clock|timed}wait.
---
 nptl/pthreadP.h               | 11 ++++++
 nptl/pthread_cond_wait.c      | 47 +++++++++++++++++++------
 sysdeps/nptl/futex-internal.h | 64 +++++++++++++++++++++++++++++++++++
 3 files changed, 112 insertions(+), 10 deletions(-)

-- 
2.20.1

Patch

diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
index 99713c8447..e288c7e778 100644
--- a/nptl/pthreadP.h
+++ b/nptl/pthreadP.h
@@ -462,6 +462,8 @@  extern int __pthread_cond_wait (pthread_cond_t *cond, pthread_mutex_t *mutex);
 #if __TIMESIZE == 64
 # define __pthread_clockjoin_np64 __pthread_clockjoin_np
 # define __pthread_timedjoin_np64 __pthread_timedjoin_np
+# define __pthread_cond_timedwait64 __pthread_cond_timedwait
+# define __pthread_cond_clockwait64 __pthread_cond_clockwait
 #else
 extern int __pthread_clockjoin_np64 (pthread_t threadid, void **thread_return,
                                      clockid_t clockid,
@@ -470,6 +472,15 @@  libc_hidden_proto (__pthread_clockjoin_np64)
 extern int __pthread_timedjoin_np64 (pthread_t threadid, void **thread_return,
                                      const struct __timespec64 *abstime);
 libc_hidden_proto (__pthread_timedjoin_np64)
+extern int __pthread_cond_timedwait64 (pthread_cond_t *cond,
+                                       pthread_mutex_t *mutex,
+                                       const struct __timespec64 *abstime);
+libc_hidden_proto (__pthread_cond_timedwait64)
+extern int __pthread_cond_clockwait64 (pthread_cond_t *cond,
+                                       pthread_mutex_t *mutex,
+                                       clockid_t clockid,
+                                       const struct __timespec64 *abstime);
+libc_hidden_proto (__pthread_cond_clockwait64)
 #endif
 
 extern int __pthread_cond_timedwait (pthread_cond_t *cond,
diff --git a/nptl/pthread_cond_wait.c b/nptl/pthread_cond_wait.c
index 85ddbc1011..c2a047b265 100644
--- a/nptl/pthread_cond_wait.c
+++ b/nptl/pthread_cond_wait.c
@@ -376,10 +376,9 @@  __condvar_cleanup_waiting (void *arg)
      can be detected when a condvar is still associated with a particular
      mutex because there is a waiter blocked on this condvar using this mutex.
 */
-static __always_inline int
+static int
 __pthread_cond_wait_common (pthread_cond_t *cond, pthread_mutex_t *mutex,
-    clockid_t clockid,
-    const struct timespec *abstime)
+    clockid_t clockid, const struct __timespec64 *abstime)
 {
   const int maxspin = 0;
   int err;
@@ -517,7 +516,7 @@  __pthread_cond_wait_common (pthread_cond_t *cond, pthread_mutex_t *mutex,
 	        err = ETIMEDOUT;
 	      else
 		{
-		  err = futex_abstimed_wait_cancelable
+		  err = futex_abstimed_wait_cancelable64
                     (cond->__data.__g_signals + g, 0, clockid, abstime,
                      private);
 		}
@@ -640,8 +639,8 @@  __pthread_cond_wait (pthread_cond_t *cond, pthread_mutex_t *mutex)
 
 /* See __pthread_cond_wait_common.  */
 int
-__pthread_cond_timedwait (pthread_cond_t *cond, pthread_mutex_t *mutex,
-    const struct timespec *abstime)
+__pthread_cond_timedwait64 (pthread_cond_t *cond, pthread_mutex_t *mutex,
+                            const struct __timespec64 *abstime)
 {
   /* Check parameter validity.  This should also tell the compiler that
      it can assume that abstime is not NULL.  */
@@ -655,6 +654,20 @@  __pthread_cond_timedwait (pthread_cond_t *cond, pthread_mutex_t *mutex,
                     ? CLOCK_MONOTONIC : CLOCK_REALTIME;
   return __pthread_cond_wait_common (cond, mutex, clockid, abstime);
 }
+
+#if __TIMESIZE != 64
+libc_hidden_def (__pthread_cond_timedwait64)
+
+int
+__pthread_cond_timedwait (pthread_cond_t *cond, pthread_mutex_t *mutex,
+                          const struct timespec *abstime)
+{
+  struct __timespec64 ts64 = valid_timespec_to_timespec64 (*abstime);
+
+  return __pthread_cond_timedwait64 (cond, mutex, &ts64);
+}
+#endif
+
 versioned_symbol (libpthread, __pthread_cond_wait, pthread_cond_wait,
 		  GLIBC_2_3_2);
 versioned_symbol (libpthread, __pthread_cond_timedwait, pthread_cond_timedwait,
@@ -662,18 +675,32 @@  versioned_symbol (libpthread, __pthread_cond_timedwait, pthread_cond_timedwait,
 
 /* See __pthread_cond_wait_common.  */
 int
-__pthread_cond_clockwait (pthread_cond_t *cond, pthread_mutex_t *mutex,
-			  clockid_t clockid,
-			  const struct timespec *abstime)
+__pthread_cond_clockwait64 (pthread_cond_t *cond, pthread_mutex_t *mutex,
+                            clockid_t clockid,
+                            const struct __timespec64 *abstime)
 {
   /* Check parameter validity.  This should also tell the compiler that
      it can assume that abstime is not NULL.  */
   if (! valid_nanoseconds (abstime->tv_nsec))
     return EINVAL;
 
-  if (!futex_abstimed_supported_clockid (clockid))
+  if (! futex_abstimed_supported_clockid (clockid))
     return EINVAL;
 
   return __pthread_cond_wait_common (cond, mutex, clockid, abstime);
 }
+
+#if __TIMESIZE != 64
+libc_hidden_def (__pthread_cond_clockwait64)
+
+int
+__pthread_cond_clockwait (pthread_cond_t *cond, pthread_mutex_t *mutex,
+                          clockid_t clockid,
+                          const struct timespec *abstime)
+{
+  struct __timespec64 ts64 = valid_timespec_to_timespec64 (*abstime);
+
+  return __pthread_cond_clockwait64 (cond, mutex, clockid, &ts64);
+}
+#endif
 weak_alias (__pthread_cond_clockwait, pthread_cond_clockwait);
diff --git a/sysdeps/nptl/futex-internal.h b/sysdeps/nptl/futex-internal.h
index 1d038e4949..ee9e91222e 100644
--- a/sysdeps/nptl/futex-internal.h
+++ b/sysdeps/nptl/futex-internal.h
@@ -520,4 +520,68 @@  futex_timed_wait_cancel64 (pid_t *tidp,  pid_t tid,
       futex_fatal_error ();
     }
 }
+
+static __always_inline int
+futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
+                                  unsigned int expected, clockid_t clockid,
+                                  const struct __timespec64* abstime,
+                                  int private)
+{
+  unsigned int clockbit;
+  int oldtype, err, op;
+
+  /* Work around the fact that the kernel rejects negative timeout values
+     despite them being valid.  */
+  if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
+    return ETIMEDOUT;
+
+  if (! lll_futex_supported_clockid (clockid))
+    return EINVAL;
+
+  oldtype = __pthread_enable_asynccancel ();
+  clockbit = (clockid == CLOCK_REALTIME) ? FUTEX_CLOCK_REALTIME : 0;
+  op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit, private);
+
+  err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op, expected,
+                               abstime, NULL /* Unused.  */,
+                               FUTEX_BITSET_MATCH_ANY);
+#ifndef __ASSUME_TIME64_SYSCALLS
+  if (err == -ENOSYS)
+    {
+      struct timespec ts32;
+      if (in_time_t_range (abstime->tv_sec))
+        {
+          ts32 = valid_timespec64_to_timespec (*abstime);
+
+          err = INTERNAL_SYSCALL_CALL (futex, futex_word, op, expected,
+                                       &ts32, NULL /* Unused.  */,
+                                       FUTEX_BITSET_MATCH_ANY);
+        }
+      else
+        err = -EOVERFLOW;
+    }
+#endif
+  __pthread_disable_asynccancel (oldtype);
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+    case -ETIMEDOUT:
+    case -EOVERFLOW:  /* Passed absolute timeout uses 64 bit time_t type, but
+                         underlying kernel does not support 64 bit time_t futex
+                         syscalls.  */
+      return -err;
+
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
+
 #endif  /* futex-internal.h */