Re: [PATCH 1/3] [RESEND] RDMA/hfi1: use a struct group to avoid warning

["yanjun.zhu" <yanjun.zhu@linux.dev>]

On 3/20/26 8:12 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> On gcc-11 and earlier, the driver sometimes produces a warning
> for memset:
> 
> In file included from include/linux/string.h:392,
>                   from drivers/infiniband/hw/hfi1/mad.c:6:
> In function 'fortify_memset_chk',
>      inlined from '__subn_get_opa_hfi1_cong_log' at drivers/infiniband/hw/hfi1/mad.c:3873:2,
>      inlined from 'subn_get_opa_sma' at drivers/infiniband/hw/hfi1/mad.c:4114:9:
> include/linux/fortify-string.h:480:4: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror]
>      __write_overflow_field(p_size_field, size);
>      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> This seems to be a false positive, and I found no nice way to rewrite
> the code to avoid the warning, but adding a a struct group works.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> resending as the patch did not get picked up last year
> https://lore.kernel.org/all/20250410075928.GN199604@unreal/
> ---
>   drivers/infiniband/hw/hfi1/hfi.h | 6 ++++--
>   drivers/infiniband/hw/hfi1/mad.c | 4 ++--
>   2 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/hfi1/hfi.h b/drivers/infiniband/hw/hfi1/hfi.h
> index 5a0310f758dc..ae17cea4e8c9 100644
> --- a/drivers/infiniband/hw/hfi1/hfi.h
> +++ b/drivers/infiniband/hw/hfi1/hfi.h
> @@ -878,8 +878,10 @@ struct hfi1_pportdata {
>   	 * cc_log_lock protects all congestion log related data
>   	 */
>   	spinlock_t cc_log_lock ____cacheline_aligned_in_smp;
> -	u8 threshold_cong_event_map[OPA_MAX_SLS / 8];
> -	u16 threshold_event_counter;
> +	struct_group (zero_event_map,
> +		u8 threshold_cong_event_map[OPA_MAX_SLS / 8];
> +		u16 threshold_event_counter;
> +	);
>   	struct opa_hfi1_cong_log_event_internal cc_events[OPA_CONG_LOG_ELEMS];
>   	int cc_log_idx; /* index for logging events */
>   	int cc_mad_idx; /* index for reporting events */
> diff --git a/drivers/infiniband/hw/hfi1/mad.c b/drivers/infiniband/hw/hfi1/mad.c
> index 585f1d99b91b..9154638e9ce2 100644
> --- a/drivers/infiniband/hw/hfi1/mad.c
> +++ b/drivers/infiniband/hw/hfi1/mad.c
> @@ -3869,8 +3869,8 @@ static int __subn_get_opa_hfi1_cong_log(struct opa_smp *smp, u32 am,
>   	 * Reset threshold_cong_event_map, and threshold_event_counter
>   	 * to 0 when log is read.
>   	 */
> -	memset(ppd->threshold_cong_event_map, 0x0,
> -	       sizeof(ppd->threshold_cong_event_map));
> +	memset(&ppd->zero_event_map, 0x0,
> +	       sizeof(ppd->zero_event_map));
>   	ppd->threshold_event_counter = 0;

Not sure if ppd->threshold_event_counter is also set to 0 in memset or 
not. If yes, this line "ppd->threshold_event_counter = 0;" can be removed?

Zhu Yanjun

>   
>   	spin_unlock_irq(&ppd->cc_log_lock);