TITLE: PTF284 - After 64K times, open of FIFO device can sleep forever README FOR: PTF284 PRODUCT AND VERSION: UnixWare 1.1.1, 1.1.2, 1.1.3, 1.1.4 Installation Instructions: DATATYPE: datastream 1. Download the ptf284.Z and ptf284.txt files to the /tmp directory on your machine. 2. Read the release notes contained in this file and follow the instuctions to add the package to your system. 3. Now become root, uncompress the file and add the package to your system using the following commands: $ su # uncompress /tmp/ptf284.Z # pkgadd -d /tmp/ptf284 Abstract -------- This PTF contains updates to the UnixWare FIFO file system driver. These updates prevent possible problems with opens of a FIFO device sleeping forever. Symptom -------- This problem is usually seen when the 'lpstat' command hangs. A 'truss' command shows that the 'lpstat' command is sleeping on the open of "/var/spool/lp/fifos/FIFO". What has happenned is that the value of an internal counter in the FIFO driver has wrapped around to become zero. Code in the open routine of the FIFO file systems needs this internal counter to be non-zero before an open is allowed. Thus, an open of this FIFO sleeps. This problem is usually seen in the 'lp' printing system because 'lpsched' always has /var/spool/lp/fifos/FIFO open. The internal counter in the FIFO file system is not decremented when closed if the file being closed is still open in another process. Thus the counter does not get decremented. SOLUTION SPECIFICS ------------------ General Description. ------------------- The updated driver increases the size of internal FIFO counters from 'short' to 'int' so that the wrap around behavior will rarely be seen. New Features. ------------ None Software Notes and Recommendations. ---------------------------------- This PTF can be installed on UnixWare 1.1.1, 1.1.2,.1.1.3, 1.1.4 systems. Testing of the modified software contained in this package has been conducted only to the extent necessary to confirm that it resolves the problem(s) stated above ("Symptom"). Such testing consists of recreating the problem conditions and verifying that the problem no longer occurs. No other testing of this software has been done. Hardware Notes and Recommendations. ---------------------------------- This PTF is targeted for the i386, i486 and Pentium CPU's.