Semaphore Count Inconsistency between Oracle Linux 7 and Oracle Linux 6 (Doc ID 2226195.1)

Last updated on APRIL 26, 2017

Applies to:

Linux OS - Version Oracle Linux 7.0 and later
Linux x86-64

Symptoms

Kernel versions greater than 3.8. ipcs -s -i <id> shows 0 for zcount,  even though a process is blocked waiting for a semaphore value to reach zero.

The process used an array of semops with multiple entries.

Example:

Four small C modules are used to create a semaphore array and then the "semid" is checked with "ipcs -s -i" command.

Only the test with "semztest2" module returns a zero value in zcount value in OL7 where it should be non zero.

Cause

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