View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0000870 | 1003.1(2013)/Issue7+TC1 | System Interfaces | public | 2014-08-25 18:11 | 2019-06-10 08:54 |
| Reporter | dalias | Assigned To | |||
| Priority | normal | Severity | Editorial | Type | Clarification Requested |
| Status | Closed | Resolution | Accepted As Marked | ||
| Name | Rich Felker | ||||
| Organization | musl libc | ||||
| User Reference | |||||
| Section | sem_close | ||||
| Page Number | 1827 | ||||
| Line Number | 58866 | ||||
| Interp Status | Approved | ||||
| Final Accepted Text | 0000870:0002399 | ||||
| Summary | 0000870: Can sem_close be called when there are waiters blocked? | ||||
| Description | The description of sem_close states "The effect of subsequent use of the semaphore indicated by sem by this process is undefined", but no mention is made of what happens when there are currently waiters. Since the state of a thread about to enter sem_wait pending being scheduled is observably indistinguishable from the state of already having entered sem_wait and blocked, I think the above text makes it acceptable for an implementation to crash or exhibit unexpected behavior if sem_close is called while there are waiters, but it would be preferable to make this explicit. | ||||
| Desired Action | Immediately after: "The effect of subsequent use of the semaphore indicated by sem by this process is undefined." add: "If any threads are currently blocked on the semaphore, the behavior is undefined." | ||||
| Tags | tc2-2008 | ||||
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That should read "If any threads in the calling process are currently blocked on the semaphore, the behavior is undefined." Obviously it's permitted to close a semaphore for which other processes have waiters. Presumably it's also permitted to close a semaphore which the current process is still using as long as the reference count will not reach zero, but the reference-counted behavior of named semaphores is not even mentioned in the description of sem_close (only sem_open); this seems to be another error in the description. |
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Interpretation response ------------------------ The standard does not speak to this issue, and as such no conformance distinction can be made between alternative implementations based on this. This is being referred to the sponsor. Rationale: ------------- There are current implementations which return mmap()ed memory and therefore a sem_close() in this situation on such implementations will result in undefined behavior. Notes to the Editor (not part of this interpretation): ------------------------------------------------------- On page 1827 line 58866 after: The effect of subsequent use of the semaphore indicated by sem by this process is undefined. add: If any threads in the calling process are currently blocked on the semaphore, the behavior is undefined. |
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Interpretation proposed 6 October 2014 |
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Interpretation approved 27 November 2014 |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2014-08-25 18:11 | dalias | New Issue | |
| 2014-08-25 18:11 | dalias | Name | => Rich Felker |
| 2014-08-25 18:11 | dalias | Organization | => musl libc |
| 2014-08-25 18:11 | dalias | Section | => sem_close |
| 2014-08-25 18:11 | dalias | Page Number | => unknown |
| 2014-08-25 18:11 | dalias | Line Number | => unknown |
| 2014-08-25 18:44 | dalias | Note Added: 0002364 | |
| 2014-10-02 16:13 | geoffclare | Note Added: 0002399 | |
| 2014-10-02 16:14 | geoffclare | Page Number | unknown => 1827 |
| 2014-10-02 16:14 | geoffclare | Line Number | unknown => 58866 |
| 2014-10-02 16:14 | geoffclare | Interp Status | => Pending |
| 2014-10-02 16:14 | geoffclare | Final Accepted Text | => 0000870:0002399 |
| 2014-10-02 16:14 | geoffclare | Status | New => Interpretation Required |
| 2014-10-02 16:14 | geoffclare | Resolution | Open => Accepted As Marked |
| 2014-10-02 16:14 | geoffclare | Tag Attached: tc2-2008 | |
| 2014-10-06 07:44 | ajosey | Interp Status | Pending => Proposed |
| 2014-10-06 07:44 | ajosey | Note Added: 0002404 | |
| 2014-11-27 10:31 | ajosey | Interp Status | Proposed => Approved |
| 2014-11-27 10:31 | ajosey | Note Added: 0002445 | |
| 2019-06-10 08:54 | agadmin | Status | Interpretation Required => Closed |
