Messages in this thread |  | | | Date | Sat, 2 Aug 2003 04:00:15 -0700 | | From | Andrew Morton <> | | Subject | Re: [PATCH] [1/2] random: SMP locking |
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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.
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