• Peter Chubb's avatar
    [PATCH] ia64: fix floating-point preemption problem · 05062d96
    Peter Chubb authored
    There've been reports of problems with CONFIG_PREEMPT=y and the high
    floating point partition.  This is caused by the possibility of preemption
    and rescheduling on a different processor while saving or restioirng the
    high partition.
    
    The only places where the FPU state is touched are in ptrace, in
    switch_to(), and where handling a floating-point exception.  In switch_to()
    preemption is off.  So it's only in trap.c and ptrace.c that we need to
    prevent preemption.
    
    Here is a patch that adds commentary to make the conditions clear, and adds
    appropriate preempt_{en,dis}able() calls to make it so.  In trap.c I use
    preempt_enable_no_resched(), as we're about to return to user space where
    the preemption flag will be checked anyway.
    Signed-off-by: default avatarPeter Chubb <peterc@gelato.unsw.edu.au>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    05062d96
traps.c 16.8 KB