[STDCXX-1072] [Oracle Solaris/SPARCV8] stricter mutex alignment requirements

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.2.1, 4.2.x, 4.3.x, 5.0.0
• Fix Version/s: 4.2.x, 4.3.x, 5.0.0
• Component/s: Thread Safety
• Labels: SPARC Solaris V8 alignment mutex

Environment

Oracle Solaris on SPARC V8 (or V9 emulation?) hardware.

• Patch Info: Patch Available
• Severity: Incorrect Behavior
• Assignee: Liviu Nicoara
• Reporter: Liviu Nicoara
• Created: 28/Sep/12 12:01
• Updated: 13/Oct/12 23:22
• Resolved: 13/Oct/12 23:20

Description

The issue has been reported in STDCXX-1040, then STDCXX-1066. The originator was apparently an improvement (as a response to CR 6296770: http://tinyurl.com/8ohjsgl) shipped with KU 137111-01 (http://tinyurl.com/ceet6ec) which requires stricter alignment than the machine word for userland mutexes.

Quoting here the Fujitsu patch notes (in case it goes away):

2) When an application using the mutex lock or rw lock in the way shown below is executed. (*1, *2) ...

      *2) ... example of programming that causes the ... problem.

        <In the case where the problem occurs>
          ----------------------------------------------------------------
          int       *ip;
          mutex_t   *mp;
          ip = (int *) malloc(sizeof (int) + sizeof (mutex_t));
          mp = (mutex_t *) (ip + 1);
                             /* The address is used with a modification */
          ----------------------------------------------------------------

        <In the case where the problem does not occur -1>
          ----------------------------------------------------------------
          mutex_t   mp;                          /* Obtained statically */
          ----------------------------------------------------------------

        <In the case where the problem does not occur -2>
          ----------------------------------------------------------------
          mutex_t   *mp;
          mp = (mutex_t *) malloc(sizeof (mutex_t));
                       /* The address is used without any modifications */
          ----------------------------------------------------------------

Issue Links

• relates to: STDCXX-1066 SPARCV8 requires pthread_mutex_t and pthread_cond_t to be aligned on an 8-byte boundary
• relates to: STDCXX-1040 Solaris 10 Kernel Update 137111-01 patches