Unlock Pointer-Based Mutex (UNLKMTX)

Operand 1: Space pointer.

Operand 2: Signed binary(4) variable scalar.

Built-in number for UNLKMTX is 158.
UNLKMTX (
         mutex   : address
) :   signed binary(4)   /* result */

Note: The term "mutex" in this instruction refers to a "pointer-based mutex".

Description

The mutex, whose address is contained in operand 1, is released (unlocked).

The mutex must be aligned on a 16-byte boundary.

The mutex must have been previously created by the CRTMTX instruction or be a copy of a mutex that was previously created by the CRTMTX instruction, and must be currently allocated to the issuer by means of a successful LOCKMTX instruction. See the CRTMTX instruction for additional information regarding mutex copies. An EPERM error number is returned if the mutex is not locked by the requesting thread.

Result is used to indicate the success or failure of the UNLKMTX instruction. If a non-recursive mutex is unlocked by this instruction, then result is set to 0. If the mutex has been recursively locked, this instruction will release one lock and result is set to a negative number whose absolute value is the number of locks which still remain on the mutex, if not 0. See the LOCKMTX instruction for additional information on using the recursive behavior of a mutex.

If an error occurs, then the result is set to an error number.

An EINVAL error number is returned if the mutex has not been initialized, or if it has been altered. The ETYPE error number is returned if the mutex operand references a synchronization object that is not a pointer-based mutex.

Authorization Required

• None

Lock Enforcement

• None

Error conditions

The result is set to one of the following:

Exceptions

06 Addressing

• 0601 Space Addressing Violation
• 0602 Boundary Alignment
• 0603 Range

08 Argument/Parameter

• 0801 Parameter Reference Violation

10 Damage Encountered

• 1004 System Object Damage State
• 1044 Partial System Object Damage

1C Machine-Dependent

• 1C03 Machine Storage Limit Exceeded

20 Machine Support

• 2002 Machine Check
• 2003 Function Check

22 Object Access

• 2202 Object Destroyed
• 2203 Object Suspended
• 2208 Object Compressed
• 220B Object Not Available

24 Pointer Specification

• 2401 Pointer Does Not Exist
• 2402 Pointer Type Invalid

2E Resource Control Limit

• 2E01 User Profile Storage Limit Exceeded

36 Space Management

• 3601 Space Extension/Truncation

44 Protection Violation

• 4401 Object Domain or Hardware Storage Protection Violation
• 4402 Literal Values Cannot Be Changed