• Paul E. McKenney's avatar
    sparc64: Eliminate obsolete __handle_softirq() function · 3d3eeb2e
    Paul E. McKenney authored
    
    
    The invocation of softirq is now handled by irq_exit(), so there is no
    need for sparc64 to invoke it on the trap-return path.  In fact, doing so
    is a bug because if the trap occurred in the idle loop, this invocation
    can result in lockdep-RCU failures.  The problem is that RCU ignores idle
    CPUs, and the sparc64 trap-return path to the softirq handlers fails to
    tell RCU that the CPU must be considered non-idle while those handlers
    are executing.  This means that RCU is ignoring any RCU read-side critical
    sections in those handlers, which in turn means that RCU-protected data
    can be yanked out from under those read-side critical sections.
    
    The shiny new lockdep-RCU ability to detect RCU read-side critical sections
    that RCU is ignoring located this problem.
    
    The fix is straightforward: Make sparc64 stop manually invoking the
    softirq handlers.
    Reported-by: default avatarMeelis Roos <mroos@linux.ee>
    Suggested-by: default avatarDavid Miller <davem@davemloft.net>
    Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
    Tested-by: default avatarMeelis Roos <mroos@linux.ee>
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    3d3eeb2e
rtrap_64.S 9.59 KB