Number: 1935

Date: 23-Aug-84 15':18':10

Submitter: JonL.pa

Source: JonL.pa

Subject: Looping around \PAGED.GETNEXTBUFFER in PF* (and others)  

Assigned To: 

Attn: vanMelle,Kaplan

Status: Open

In/By: 

Problem Type: Bug

Impact: Annoying

Difficulty: Moderate

Frequency: Intermittent

Priority: Perhaps

System: Operating System

Subsystem: Other

Machine: 

Disk: 

Lisp Version: 15-Aug-84 20':42':17

Source Files: 

Microcode Version: 5124

Memory Size: 4096

File Server: 

Server Software Version: 

Disposition: '
["JonL.pa" "31-Aug-84 22':52':29" Subject': Attn': Status':(Incomplete->New) System':(Programming% Environment->Operating% System) Subsystem':(File% Package->Other) Disposition': Description':]'
["JonL.pa" "31-Aug-84 22':58':42" Subject': Attn': Status':(Incomplete->New) System':(Programming% Environment->Operating% System) Subsystem':(File% Package->Other) Disposition': Description': Edit-Date':]'
["masinter.PA" " 4-Sep-84 13':16':17" Status':(New->Open)]

Description: [formerly, the Subject was "PF* (and others) fail to BLOCK when auto-updating a filemap].  When a filemap is discovered to be misplaced (possibly due to someone having edited the file on MAXC and PUPFTP''ing it to ERIS), then it seems that the call to FINDFNDEF, untimately below PF*, causes a deadlock condition between \BUFFERE.BIN and \PAGED.GETNEXTBUFFER; thus the world seems to go catatonic underneath the one call to READC in FINDFNDEF, which is done just after a lot of SETFILEPTRing around.  In  the current example of the bug (in the sysout from which this AR is being edited), I find that the leaf stream has COFFSET of 152 and CBUFSIZE of 0 and CBUFPTR of some-random-VMEMPAGEP.  A comment in \PAGED.GETNEXTBUFFER says, with respect to this situation, "Is ok, why were we called?", and proceeds to return T; yet \BUFFERED.BIN finds that the COFFSET is greater than the CBUFSIZE, and immediately calls \PAGED.GETNEXTBUFFER again.  An infinite, non-BLOCKing, loop.'
  

Workaround: 

Test Case: 

Edit-By: masinter.PA

Edit-Date:  4-Sep-84 13':16':19