Re: [PATCH] err.h: allow IS_ERR_VALUE to handle properly more types

[Andrzej Hajda]

Hi Andrew,

Have you looked at this patch?
Are there chances to merge it to next?

Two more things I have found:
- current version of IS_ERR_VALUE does not work with unsigned long long
on 32bit arch - commit message should be fixed,
- gcc issues warnings when -Wtype-limits option is enabled, it can be
easily silenced by changing first operator '<' to '<=' in the macro.

Regards
Andrzej

On 01/07/2016 03:58 PM, Andrzej Hajda wrote:
> Current implementation of IS_ERR_VALUE works correctly only with
> following types:
> - unsigned long, unsigned long long,
> - short, int, long.
> Other types are handled incorrectly either on 32-bit either on 64-bit
> either on both architectures.
> The patch fixes it by comparing argument with MAX_ERRNO casted
> to argument's type for unsigned types and comparing with zero for signed
> types. As a result all integer types bigger than char are handled properly.
> 
> Signed-off-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
> ---
> Hi,
> 
> I have analyzed usage of IS_ERR_VALUE using coccinelle and in about 35 cases
> it is used incorrectly, ie it can hide errors depending of 32/64 bit architecture.
> Instead of fixing usage I propose to enhance the macro to cover more types.
> And just for record: the macro is used 101 times with signed variables, I am not
> sure if it should be preferred over simple comparison "ret < 0", but the new version
> can do it as well.
> 
> In my previous attempt I have added type checking to the macro, I am not sure which
> approach is better[1]. Anyway the previous patch did not catch developers attention.
> 
> [1]: http://permalink.gmane.org/gmane.linux.kernel/2111532
> 
> And below list of detected potential errors:
> drivers/char/mem.c:698:45-46: WARNING: incorrect argument type in IS_ERR_VALUE(( unsigned long long ) offset)
> drivers/media/platform/soc_camera/atmel-isi.c:1089:21-22: WARNING: incorrect argument type in IS_ERR_VALUE(irq)
> drivers/net/ethernet/freescale/fs_enet/mac-scc.c:149:36-37: WARNING: incorrect argument type in IS_ERR_VALUE(fep -> ring_mem_addr)
> drivers/net/ethernet/freescale/ucc_geth.c:2237:48-49: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> tx_bd_ring_offset [ j ])
> drivers/net/ethernet/freescale/ucc_geth.c:2314:48-49: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> rx_bd_ring_offset [ j ])
> drivers/net/ethernet/freescale/ucc_geth.c:2524:44-45: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> tx_glbl_pram_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:2544:45-46: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> thread_dat_tx_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:2571:46-47: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> send_q_mem_reg_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:2612:42-43: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> scheduler_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:2659:54-55: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> tx_fw_statistics_pram_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:2696:44-45: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> rx_glbl_pram_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:2715:45-46: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> thread_dat_rx_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:2736:54-55: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> rx_fw_statistics_pram_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:2756:53-54: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> rx_irq_coalescing_tbl_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:2822:44-45: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> rx_bd_qs_tbl_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:2908:47-48: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> exf_glbl_param_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:292:36-37: WARNING: incorrect argument type in IS_ERR_VALUE(init_enet_offset)
> drivers/net/ethernet/freescale/ucc_geth.c:3042:39-40: WARNING: incorrect argument type in IS_ERR_VALUE(init_enet_pram_offset)
> drivers/soc/fsl/qe/ucc_fast.c:271:60-61: WARNING: incorrect argument type in IS_ERR_VALUE(uccf -> ucc_fast_tx_virtual_fifo_base_offset)
> drivers/soc/fsl/qe/ucc_fast.c:284:60-61: WARNING: incorrect argument type in IS_ERR_VALUE(uccf -> ucc_fast_rx_virtual_fifo_base_offset)
> drivers/soc/fsl/qe/ucc_slow.c:186:38-39: WARNING: incorrect argument type in IS_ERR_VALUE(uccs -> us_pram_offset)
> drivers/soc/fsl/qe/ucc_slow.c:213:38-39: WARNING: incorrect argument type in IS_ERR_VALUE(uccs -> rx_base_offset)
> drivers/soc/fsl/qe/ucc_slow.c:224:38-39: WARNING: incorrect argument type in IS_ERR_VALUE(uccs -> tx_base_offset)
> drivers/tty/serial/clps711x.c:471:29-30: WARNING: incorrect argument type in IS_ERR_VALUE(s -> port . irq)
> drivers/tty/serial/digicolor-usart.c:485:30-31: WARNING: incorrect argument type in IS_ERR_VALUE(dp -> port . irq)
> drivers/usb/gadget/udc/fsl_qe_udc.c:2369:26-27: WARNING: incorrect argument type in IS_ERR_VALUE(tmp_addr)
> drivers/video/fbdev/exynos/exynos_mipi_dsi.c:406:27-28: WARNING: incorrect argument type in IS_ERR_VALUE(dsim -> irq)
> net/ipv4/netfilter/arp_tables.c:1427:39-40: WARNING: incorrect argument type in IS_ERR_VALUE(iter1 -> counters . pcnt)
> net/ipv4/netfilter/arp_tables.c:530:34-35: WARNING: incorrect argument type in IS_ERR_VALUE(e -> counters . pcnt)
> net/ipv4/netfilter/ip_tables.c:1614:34-35: WARNING: incorrect argument type in IS_ERR_VALUE(e -> counters . pcnt)
> net/ipv4/netfilter/ip_tables.c:674:34-35: WARNING: incorrect argument type in IS_ERR_VALUE(e -> counters . pcnt)
> net/ipv6/netfilter/ip6_tables.c:1624:34-35: WARNING: incorrect argument type in IS_ERR_VALUE(e -> counters . pcnt)
> net/ipv6/netfilter/ip6_tables.c:687:34-35: WARNING: incorrect argument type in IS_ERR_VALUE(e -> counters . pcnt)
> drivers/net/ethernet/freescale/fs_enet/mac-fcc.c:110:35-36: WARNING: unknown argument type in IS_ERR_VALUE(fpi -> dpram_offset)
> 
> Regards
> Andrzej
> 
>  include/linux/err.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/err.h b/include/linux/err.h
> index 56762ab..40eca39 100644
> --- a/include/linux/err.h
> +++ b/include/linux/err.h
> @@ -18,7 +18,9 @@
>  
>  #ifndef __ASSEMBLY__
>  
> -#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
> +#define IS_ERR_VALUE(x) ((typeof(x))(-1) < 0 \
> +				? unlikely((x) < 0) \
> +				: unlikely((x) >= (typeof(x))-MAX_ERRNO))
>  
>  static inline void * __must_check ERR_PTR(long error)
>  {
>