• Aaron Tomlin's avatar
    module: kallsyms: Ensure preemption in add_kallsyms() with PREEMPT_RT · e69a6614
    Aaron Tomlin authored
    The commit 08126db5 ("module: kallsyms: Fix suspicious rcu usage")
    under PREEMPT_RT=y, disabling preemption introduced an unbounded
    latency since the loop is not fixed. This change caused a regression
    since previously preemption was not disabled and we would dereference
    RCU-protected pointers explicitly. That being said, these pointers
    cannot change.
    
    Before kallsyms-specific data is prepared/or set-up, we ensure that
    the unformed module is known to be unique i.e. does not already exist
    (see load_module()). Therefore, we can fix this by using the common and
    more appropriate RCU flavour as this section of code can be safely
    preempted.
    Reported-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    Fixes: 08126db5 ("module: kallsyms: Fix suspicious rcu usage")
    Signed-off-by: default avatarAaron Tomlin <atomlin@redhat.com>
    Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
    e69a6614
kallsyms.c 14.2 KB