On Thu, Jul 07, 2016 at 08:57:29PM +0530, Arvind Yadav wrote:
> Passing value in IS_ERR_VALUE() is wrong, as they
> pass an 'int' into a function that takes an 'unsigned long'
> argument. This happens to work because the type is sign-extended
> on 64-bit architectures before it gets converted into an
> unsigned type.
>
> Passing an 'unsigned short' or 'unsigned int'
> argument into IS_ERR_VALUE() is guaranteed to be broken, as are
> 8-bit integers and types that are wider than 'unsigned long'.
>
> Any user will get compilation warning for that do not pass an
> 'unsigned long' argument.
>
> Commit '287980e49f; - This change is alreday fixes lots of other
> worst abusers.
>
Couple of generic comments:
- Your patch subject lines don't include the affected drivers/modules.
As such, most of them will be ignored because maintainers won't realize
that you are talking with them. Some may ask you to resubmit with proper
subject lines.
Commit 287980e49f is different; it addresses the problem in several
drivers in a single commit.
- If you patch a single file, I think it would be better to adjust the
description accordingly. In this patch, the offending variable type is
u32. The patch description is therefore misleading; the code here simply does
not work.
- When you resubmit a patch, you don't include a version, not a change log.
This means additional work for maintainers, who have to figure out which
patch to apply.
Specific comment:
The allocator in question returns -ENOMEM in an unsigned long. This is assigned
to u32. A proper fix would be to assign the return value to an unsigned
long and to use IS_ER_VALUE() to check if it reports an error, and to only
assign it to ucc_fast_rx_virtual_fifo_base_offset if there was no error.
Also, unless I am missing something - since ucc_fast_rx_virtual_fifo_base_offset
is defined as u32, it is somewhat unlikely that it is ever < 0.
Guenter
> Signed-off-by: Arvind Yadav <arvind.yadav...@gmail.com>
> ---
> drivers/soc/fsl/qe/ucc_fast.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/soc/fsl/qe/ucc_fast.c b/drivers/soc/fsl/qe/ucc_fast.c
> index a768931..7cc783c 100644
> --- a/drivers/soc/fsl/qe/ucc_fast.c
> +++ b/drivers/soc/fsl/qe/ucc_fast.c
> @@ -268,7 +268,7 @@ int ucc_fast_init(struct ucc_fast_info * uf_info, struct
> ucc_fast_private ** ucc
> /* Allocate memory for Tx Virtual Fifo */
> uccf->ucc_fast_tx_virtual_fifo_base_offset =
> qe_muram_alloc(uf_info->utfs, UCC_FAST_VIRT_FIFO_REGS_ALIGNMENT);
> - if (IS_ERR_VALUE(uccf->ucc_fast_tx_virtual_fifo_base_offset)) {
> + if (uccf->ucc_fast_tx_virtual_fifo_base_offset < 0) {
> printk(KERN_ERR "%s: cannot allocate MURAM for TX FIFO\n",
> __func__);
> uccf->ucc_fast_tx_virtual_fifo_base_offset = 0;
> @@ -281,7 +281,7 @@ int ucc_fast_init(struct ucc_fast_info * uf_info, struct
> ucc_fast_private ** ucc
> qe_muram_alloc(uf_info->urfs +
> UCC_FAST_RECEIVE_VIRTUAL_FIFO_SIZE_FUDGE_FACTOR,
> UCC_FAST_VIRT_FIFO_REGS_ALIGNMENT);
> - if (IS_ERR_VALUE(uccf->ucc_fast_rx_virtual_fifo_base_offset)) {
> + if (uccf->ucc_fast_rx_virtual_fifo_base_offset < 0) {
> printk(KERN_ERR "%s: cannot allocate MURAM for RX FIFO\n",
> __func__);
> uccf->ucc_fast_rx_virtual_fifo_base_offset = 0;
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