Messages in this thread | | | Date | Sat, 2 Aug 2003 08:35:22 -0400 (EDT) | From | Zwane Mwaikambo <> | Subject | Re: [PATCH] [1/2] random: SMP locking |
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On Sat, 2 Aug 2003, Andrew Morton wrote:
> Oliver Xymoron <oxymoron@waste.org> wrote: > > > > This patch adds locking for SMP. Apparently Willy never managed to > > revive his laptop with his version so I revived mine. > > hrm. I'm a random ignoramus. I'll look it over... > > Are you really sure that all the decisions about where to use spin_lock() > vs spin_lock_irq() vs spin_lock_irqsave() are correct? They are > non-obvious. > > > @@ -1619,18 +1660,23 @@ > > if (!capable(CAP_SYS_ADMIN)) > > return -EPERM; > > p = (int *) arg; > > + spin_lock(&random_state->lock); > > ent_count = random_state->entropy_count; > > if (put_user(ent_count, p++) || > > get_user(size, p) || > > put_user(random_state->poolinfo.poolwords, p++)) > > Cannot perform userspace access while holding a lock - a pagefault could > occur, perform IO, schedule away and the same CPU tries to take the same > lock via a different process.
Perhaps might_sleep() in *_user, copy_* etc is in order?
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