Re: [PATCH] Lockdep treats down_write_trylock like regular down_write

[Arjan van de Ven]

Pavel Emelianov wrote:
> This causes constructions like
>
> down_write(&mm1->mmap_sem);
> if (down_write_trylock(&mm2->mmap_sem)) {
>        ...
>        up_write(&mm2->mmap_sem);
> }
> up_write(&mm1->mmap_sem);
>
> generate a lockdep warning about circular locking dependence.

please show me why this is safe, especially if you intermix it with 
down_read()'s... like copy_to_user and co may do.

this feels like a very unsafe construct to me...
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/