cvs commit: src/sys/vm uma_core.c

[Robert Watson]

rwatson     2005-07-23 15:08:53 UTC

  FreeBSD src repository

  Modified files:        (Branch: RELENG_6)
    sys/vm               uma_core.c 
  Log:
  Merge uma_core.c:1.125 from HEAD to RELENG_5:
  
    Move the unlocking of the zone mutex in sysctl_vm_zone_stats() so that
    it covers the following of the uc_alloc/freebucket cache pointers.
    Originally, I felt that the race wasn't helped by holding the mutex,
    hence a comment in the code and not holding it across the cache access.
    However, it does improve consistency, as while it doesn't prevent
    bucket exchange, it does prevent bucket pointer invalidation.  So a
    race in gathering cache free space statistics still can occur, but not
    one that follows an invalid bucket pointer, if the mutex is held.
  
    Submitted by:   yongari
  
  Approved by:    re (kensmith)
  
  Revision   Changes    Path
  1.119.2.6  +9 -5      src/sys/vm/uma_core.c