Hi Dan,
On 2020/6/2 21:54, Dan Carpenter wrote:
> Originally this code rejected any read less than 256 bytes. There
> is no need for this artificial limit. We should just use the normal
> helper functions to read a string from the kernel.
>
> Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>
> ---
> v2: Use simple_read_from_buffer(). The v1 was slightly half arsed
> because I left the original check for:
>
> if (*pos)
> return 0;
>
> So it could result in partial reads. The new code means that if you
> want to read the buffer one byte at a time, that's fine or if you want
> to read it in one 256 byte chunk that's also fine. Plus it deletes 21
> lines of code and is a lot cleaner.
>
In fact, In our original design, we do not hope the user do the partial reads.
Thank you for your work, but I still insist on adding this limit.
Thanks,
Shukun
> drivers/crypto/hisilicon/qm.c | 33 ++++++---------------------------
> 1 file changed, 6 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/crypto/hisilicon/qm.c b/drivers/crypto/hisilicon/qm.c
> index 9bb263cec6c30..13ccb9e29a2e1 100644
> --- a/drivers/crypto/hisilicon/qm.c
> +++ b/drivers/crypto/hisilicon/qm.c
> @@ -1064,19 +1064,10 @@ static ssize_t qm_cmd_read(struct file *filp, char
> __user *buffer,
> char buf[QM_DBG_READ_LEN];
> int len;
>
> - if (*pos)
> - return 0;
> -
> - if (count < QM_DBG_READ_LEN)
> - return -ENOSPC;
> + len = scnprintf(buf, QM_DBG_READ_LEN, "%s\n",
> + "Please echo help to cmd to get help information");
>
> - len = snprintf(buf, QM_DBG_READ_LEN, "%s\n",
> - "Please echo help to cmd to get help information");
> -
> - if (copy_to_user(buffer, buf, len))
> - return -EFAULT;
> -
> - return (*pos = len);
> + return simple_read_from_buffer(buffer, count, pos, buf, len);
> }
>
> static void *qm_ctx_alloc(struct hisi_qm *qm, size_t ctx_size,
> @@ -2691,24 +2682,12 @@ static ssize_t qm_status_read(struct file *filp, char
> __user *buffer,
> {
> struct hisi_qm *qm = filp->private_data;
> char buf[QM_DBG_READ_LEN];
> - int val, cp_len, len;
> -
> - if (*pos)
> - return 0;
> -
> - if (count < QM_DBG_READ_LEN)
> - return -ENOSPC;
> + int val, len;
>
> val = atomic_read(&qm->status.flags);
> - len = snprintf(buf, QM_DBG_READ_LEN, "%s\n", qm_s[val]);
> - if (!len)
> - return -EFAULT;
> -
> - cp_len = copy_to_user(buffer, buf, len);
> - if (cp_len)
> - return -EFAULT;
> + len = scnprintf(buf, QM_DBG_READ_LEN, "%s\n", qm_s[val]);
>
> - return (*pos = len);
> + return simple_read_from_buffer(buffer, count, pos, buf, len);
> }
>
> static const struct file_operations qm_status_fops = {
>
