Utilizing access control data structures for sharing computing resources

• US 9,853,908 B2
• Filed: 11/25/2014
• Issued: 12/26/2017
• Est. Priority Date: 11/25/2014
• Status: Active Grant

• Current Assignee: Red Hat, Inc. (International Business Machines Corporation)
• Original Assignee: Red Hat, Inc. (International Business Machines Corporation)
• Inventors: Riegel, Torvald
• Primary Examiner(s): Rashid, Wissam
• Application Number:
  US14/552,741
• Publication Number:
  US 20160149824A1
• Time in Patent Office: 1,127 Days
• Field of Search: None
• CPC Class Codes: G06F 21/604 Tools and structures for managing or administering access control systems
• CPC Class Codes: G06F 9/46 Multiprogramming arrangements
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms
• CPC Class Codes: H04L 47/70 Admission control; Resource allocation

Abstract

Systems and methods for sharing resources between multiple processing streams. An example method may comprise: maintaining, by a processing device, a first variable identifying a number of processing streams waiting to access a resource; performing an atomic operation on a second variable comprising a first portion and a second portion, the atomic operation comprising incrementing the first portion to reflect a number of available units of the resource and further comprising reading the second portion reflecting a value of the first variable.

Claims

1. A method comprising:

maintaining, by a processing device, a first variable identifying a number of processing streams waiting to access a resource;

performing an atomic operation on a second variable comprising a first portion and a second portion, the atomic operation comprising incrementing the first portion to reflect a number of available units of the resource and further comprising reading the second portion reflecting a value of the first variable.

2. The method of claim 1, wherein the second portion of the second variable comprises an embedded indicator portion reflecting the value of the first variable is non-zero.

3. The method of claim 1, wherein the processing streams comprise at least one of a thread or a process.

4. The method of claim 1, wherein the first variable and the second variable are part of an access control data structure associated with the resource.

5. The method of claim 1, wherein the first variable and the second variable comprise a combined size that is larger than an atomic access unit of the atomic operation.

6. The method of claim 2, wherein the embedded indicator portion comprises a single bit of the second variable.

7. The method of claim 1, wherein the atomic operation is initiated by a POSIX POST call that makes a unit of the resource available for consumption.

8. The method of claim 4, wherein the access control data structure is a semaphore data structure.

9. The method of claim 8, further comprises destroying the semaphore data structure prior to a completion of a POST call that incremented the second variable of the semaphore data structure.

10. The method of claim 1 further comprising:

incrementing the first variable to increase the number of processing streams waiting to access the resource; and

setting the second portion of the second variable to indicate the first variable is not zero.

11. A system comprising:

a memory; and

a processing device communicably coupled to the memory, the processing device to execute instructions to;

maintain a first variable identifying a number of processing streams waiting to access a resource;

perform an atomic operation on a second variable comprising a first portion and a second portion, the atomic operation comprising incrementing the first portion to reflect a number of available units of the resource and further comprising reading the second portion reflecting a value of the first variable.

12. The system of claim 11, wherein the second portion of the second variable comprises an embedded indicator portion reflecting the value of the first variable is non-zero.

13. The system of claim 11, wherein the processing streams comprise at least one of a thread or a process.

14. The system of claim 11, wherein the first variable and the second variable are part of an access control data structure associated with the resource.

15. The system of claim 11, wherein a combined size of the first variable and the second variable is larger than an atomic access unit of the atomic operation.

16. The system of claim 11, wherein the atomic operation is initiated by a POSIX POST call that makes a unit of the resource available for consumption.

17. The system of claim 14, wherein the access control data structure is a semaphore data structure.

18. The system of claim 17, wherein the processing device further to destroy the semaphore data structure prior to a completion of a POST call that incremented the second variable of the semaphore data structure.

19. The system of claim 11, wherein the processing device further to:

increment the first variable to increase the number of processing streams waiting to access the resource; and

set the second portion of the second variable to indicate the first variable is not zero.

20. A non-transitory machine-readable storage medium storing instructions which, when executed, cause a processing device to execute operations comprising:

maintain a first variable identifying a number of processing streams waiting to access a resource;

perform an atomic operation on a second variable comprising a first portion and a second portion, the atomic operation comprising incrementing the first portion to reflect a number of available units of the resource and further comprising reading the second portion reflecting a value of the first variable.