Yes, agreed. Using the macro (), as done in the patch, is the correct
way to avoid invalid pointer dereferencing.
Tested with patch-3.14.25-rt22 patch on a 2 socket platform.
Reviewed-by: T Makphaibulchoke <tmac@xxxxxxx>
Tested-by: T Makphaibulchoke <tmac@xxxxxxx>
On 12/05/2014 12:35 PM, Brad Mouring wrote:
> In task_blocks_on_lock, there's a null check on pi_blocked_on
> of the task_struct. This pointer can encode the fact that the
> task that contains the pointer is waking (preventing requeuing)
> and therefore is non-null. Use the inline function to avoid
> dereferencing an invalid "pointer"
>
> Signed-off-by: Brad Mouring <brad.mouring@xxxxxx>
> Reported-by: Ben Shelton <ben.shelton@xxxxxx>
> ---
> kernel/locking/rtmutex.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
> index 6c40660..535321e 100644
> --- a/kernel/locking/rtmutex.c
> +++ b/kernel/locking/rtmutex.c
> @@ -335,7 +335,8 @@ int max_lock_depth = 1024;
>
> static inline struct rt_mutex *task_blocked_on_lock(struct task_struct *p)
> {
> - return p->pi_blocked_on ? p->pi_blocked_on->lock : NULL;
> + return rt_mutex_real_waiter(p->pi_blocked_on) ?
> + p->pi_blocked_on->lock : NULL;
> }
>
> /*
>
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