Method and system for robust futexes

• US 20080189282A1
• Filed: 02/01/2007
• Published: 08/07/2008
• Est. Priority Date: 02/01/2007
• Status: Active Grant

• Current Assignee: Red Hat, Inc. (International Business Machines Corporation)
• Original Assignee: Red Hat, Inc. (International Business Machines Corporation)
• Inventors: Drepper, Ulrich, Molnar, Ingo, Glelxner, Thomas
• Granted Patent: US 7,783,649 B2
• Time in Patent Office: Days
• US Class Current: 707/8
• CPC Class Codes: G06F 16/2343 Locking methods, e.g. distributed locking or locking implementation details
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

An embodiment relates to a method of managing primitives. The method includes providing a data structure available in user-space where the data structure comprises at least one futex. The method also includes detecting a termination of the process and searching the data structure for status of the at least one futex. The method further includes releasing the at least one futex in response to status of the at least one futex being held and setting a flag for at least one futex. The method further includes notifying at least one process waiting for the released at least one futex.

Claims

1. A method of managing primitives, the method comprising:

providing a data structure available in user-space, the data structure comprising at least one futex;

detecting a termination of a process;

searching the data structure for status of the at least one futex;

releasing the at least one futex in response to status of the at least one futex being held;

setting a flag for at least one futex; and

notifying at least one process waiting for the released at least one futex.

2. The method of claim 1, further comprising:

checking a status of the flag by an awaken process; and

processing an associated futex with the flag.

3. The method of claim 1, further comprising unlinking the at least one futex from the data structure.

4. The method of claim 1, further comprising:

acquiring a free futex; and

linking the free futex to the data structure.

5. The method of claim 4, further comprising setting the status of free futex as locked.

6. The method of claim 1, further comprising executing a function call to determine the location of the data structure.

7. The method of claim 1, further comprising:

providing for a second data structure;

acquiring a selected futex from a plurality of futexes by the process; and

setting a flag in the second data structure indicating the process is about to lock the selected futex.

8. The method of claim 7, further comprising linking the first data structure to the second data structure.

9. A method of managing exclusion primitives, the method comprising:

registering a first data structure and a second data structure by a process, wherein the first and second data structures are linked;

acquiring a selected robust futex from a plurality of robust futexes;

setting at least one flag in the second data structure, wherein the flag indicates the process is about to be locking the selected robust futex.

10. The method of claim 9, further comprising:

linking the selected robust futex with the first data structure in response to the selected robust futex being locked by the process; and

resetting the flag in the second data structure.

11. The method of claim 10, further comprising:

determining the selected robust futex is being released;

unlinking the selected robust futex from the first data structure.

12. The method of claim 11, further comprising releasing the selected robust futex.

13. The method of claim 10, further comprising:

detecting a termination of the process;

searching the first data structure for a status of the selected robust futex; and

setting a second flag indicating that the process terminated in response to the status of the selected robust futex being locked from the first data structure and the flag in the second data structure being set.

14. The method of claim 13, further comprising awakening at least one process waiting for the selected robust futex.

15. A system for managing primitives, the system comprising:

a first data structure configured to store futexes designated as being held;

a second data structure configured to store a flag and linked to the first data structure, wherein the first and second data structures are in user space; and

a futex module configured to setting at least one flag in the second data structure in response to acquiring a selected robust futex from a plurality of robust futexes, wherein the flag indicates the process is about to be locking the selected robust futex.

16. The system of claim 15, wherein the futex module is further configured to link the selected robust futex with the first data structure in response to the selected robust futex being locked by the process and to reset the flag in the second data structure.

17. The system of claim 16, wherein the futex module is further configured to determine the selected robust futex is being released and unlink the selected robust futex from the first data structure.

18. The system of claim 17, wherein the futex module is further configured to release the selected robust futex.

19. The system of claim 18, wherein the futex module is further configured to detect a termination of the process, search the first data structure for a status of the selected robust futex;

and set a second flag indicating that the process terminated in response to the status of the selected robust futex being locked from the first data structure and the flag in the second data structure being set.

20. The system of claim 19, wherein the futex module is further configured to waken at least one process waiting for the selected robust futex.