Re: [PATCH v2] livepatch: add locking to force and signal functions

[Josh Poimboeuf]

On Thu, Dec 21, 2017 at 02:40:43PM +0100, Miroslav Benes wrote:
> klp_send_signals() and klp_force_transition() do not acquire klp_mutex,
> because it seemed to be superfluous. A potential race in
> klp_send_signals() was harmless and there was nothing in
> klp_force_transition() which needed to be synchronized. That changed
> with the addition of klp_forced variable during the review process.
> 
> There is a small window now, when klp_complete_transition() does not see
> klp_forced set to true while all tasks have been already transitioned to
> the target state. module_put() is called and the module can be removed.
> 
> Acquire klp_mutex in sysfs callback to prevent it. Do the same for the
> signal sending just to be sure. There is no real downside to that.
> 
> Reported-by: Jason Baron <jbaron@xxxxxxxxxx>
> Signed-off-by: Miroslav Benes <mbenes@xxxxxxx>

Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

-- 
Josh