On Tue, Aug 02, 2016 at 09:42:06PM -0700, Rodrigo Vivi wrote:
> Copy to user return the number of bytes it couldn't write
> and zero on success. So any number different than 0 should
> be considered a fault, not only when it doesn't write
> the full size.
>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
I audited all the other places we use copy_*_user. We have a bit a mess
between negative errno and unwritten bytes for our own copy functions, but
seems consistent (except this one here).
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 7c42ec4..7052c47 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -3632,7 +3632,6 @@ i915_pipe_crc_read(struct file *filep, char __user *user_buf, size_t count,
> while (n_entries > 0) {
> struct intel_pipe_crc_entry *entry =
> &pipe_crc->entries[pipe_crc->tail];
> - int ret;
>
> if (CIRC_CNT(pipe_crc->head, pipe_crc->tail,
> INTEL_PIPE_CRC_ENTRIES_NR) < 1)
> @@ -3649,8 +3648,7 @@ i915_pipe_crc_read(struct file *filep, char __user *user_buf, size_t count,
>
> spin_unlock_irq(&pipe_crc->lock);
>
> - ret = copy_to_user(user_buf, buf, PIPE_CRC_LINE_LEN);
> - if (ret == PIPE_CRC_LINE_LEN)
> + if (!copy_to_user(user_buf, buf, PIPE_CRC_LINE_LEN))
> return -EFAULT;
>
> user_buf += PIPE_CRC_LINE_LEN;
> --
> 2.5.5
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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