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SubjectRe: [PATCH v8 08/12] user_events: Optimize writing events by only copying data once
On Thu, 16 Dec 2021 09:35:07 -0800
Beau Belgrave <beaub@linux.microsoft.com> wrote:

> @@ -1018,16 +1081,11 @@ static ssize_t user_events_write_core(struct file *file, struct iov_iter *i)
> if (likely(atomic_read(&tp->key.enabled) > 0)) {
> struct tracepoint_func *probe_func_ptr;
> user_event_func_t probe_func;
> + struct iov_iter copy;
> void *tpdata;
> - void *kdata;
> - u32 datalen;
> -
> - kdata = kmalloc(i->count, GFP_KERNEL);
>
> - if (unlikely(!kdata))
> - return -ENOMEM;
> -
> - datalen = copy_from_iter(kdata, i->count, i);
> + if (unlikely(iov_iter_fault_in_readable(i, i->count)))

Can you rebase on my tree: ftrace/core ?

That's because upstream now has:

a6294593e8a12 ("iov_iter: Turn iov_iter_fault_in_readable into fault_in_iov_iter_readable")

And it looks like you need to call fault_in_iov_iter_readable().

-- Steve


> + return -EFAULT;
>
> rcu_read_lock_sched();
>

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