lkml.org 
[lkml]   [2008]   [Aug]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] Remove stop_machine during module load
    Hi Paul,

    Thanks for the excellent review.

    On Fri, Aug 29, 2008 at 01:44:57PM -0700, Paul E. McKenney wrote:
    >
    > OK, what about the read side? Not so good for __unlink_module() to yank

    That's independent from my patch isn't it? I don't think I'm changing
    anything here. All of the issues you're pointing out are already
    in the code (except for the missing read_barrier_depends() perhaps)

    I think the lockless users like oops or sysrq-t typically have preemption
    disabled, so they should be ok regarding that.

    > the module out from under a reader. Therefore, all readers must either
    > disable interrupts to block stop_machine() or must hold some sort of
    > mutex that prevents modules from being unloaded.
    >
    > First, where the heck -is- the read side...
    >
    > o each_symbol() needs its list_for_each_entry() to become
    > list_for_each_entry_rcu() and needs local_irq_disable()

    Ah that's needed for the Alpha barrier depends semantics,
    right?

    > Yet another approach would be to use call_rcu() to defer the
    > various kfree() &c calls later in free_module.

    I think that would be a the better approach.

    -Andi



    \
     
     \ /
      Last update: 2008-08-29 23:23    [W:3.050 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site