cvs commit: src/sys/sparc64/sparc64 exception.S interrupt.S

Marius Strobl marius at
Mon Apr 17 21:03:24 UTC 2006

marius      2006-04-17 21:03:24 UTC

  FreeBSD src repository

  Modified files:
    sys/sparc64/sparc64  exception.S interrupt.S 
  - Since critical sections no longer raise the processor interrupt level to
    above what's used for fast interrupts, only interrupts with the level of
    the interrupt which led to calling intr_fast() (which is used with both
    fast and ithread interrupts) are blocked while in that function. Thus
    intr_fast() can be preempted by a fast interrupt (which are of a higher
    level than ithread interrupts) while servicing an ithread interrupt. This
    can lead to a stale pointer to the head of the active interrupt requests
    list when back in the ithread interrupt invocation of intr_fast(), in turn
    resulting in corruption of the interrupt request lists and consequently
    in a panic. Solve this be turning off interrupts in intr_fast() before
    reading the pointer to the head of the active list rather than after. [1]
  - Add a KASSERT in intr_fast() which asserts that ir_func is non-zero before
    calling it. [1]
  - Increment interrupt stats after calling the handlers rather than before.
    This reduces the delay until direct and fast handlers are serviced, in my
    testings by 30% on average for the direct tick interrupt handler, in turn
    resulting in less clock drift.
  PR:             94778 [1]
  Submitted by:   Andrew Belashov [1]
  MFC after:      2 weeks
  Revision  Changes    Path
  1.73      +26 -26    src/sys/sparc64/sparc64/exception.S
  1.9       +20 -12    src/sys/sparc64/sparc64/interrupt.S

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