Re: [PATCH v3 4/6] alloc_tag: add accuracy based filtering to ioctl

[Hao Ge <hao.ge@linux.dev>]

Hi Abhishek


On 2026/6/6 07:36, Abhishek Bapat wrote:
> Extend the allocinfo filtering mechanism to allow users to filter tags
> based on their accuracy.
>
> Signed-off-by: Abhishek Bapat <abhishekbapat@google.com>
> ---
>   include/uapi/linux/alloc_tag.h | 3 +++
>   lib/alloc_tag.c                | 8 ++++++++
>   2 files changed, 11 insertions(+)
>
> diff --git a/include/uapi/linux/alloc_tag.h b/include/uapi/linux/alloc_tag.h
> index 0e648192df4d..42445bdb11c5 100644
> --- a/include/uapi/linux/alloc_tag.h
> +++ b/include/uapi/linux/alloc_tag.h
> @@ -20,6 +20,7 @@ struct allocinfo_tag {
>   	char function[ALLOCINFO_STR_SIZE];
>   	char filename[ALLOCINFO_STR_SIZE];
>   	__u64 lineno;
> +	__u64 inaccurate;


I was wondering if it would make sense to define inaccurate as a flags field

(e.g. __u64 flags with ALLOCINFO_TAG_F_INACCURATE (1 <<0)),

so that only bit 0 is used today and the upper bits are reserved for 
future use,

aligning with current kernel codebase.

This design also allows for better extensibility if we need to

add new flags for any reason in the future.

We also need to add flag validity checks if we go this route.


Thanks

Best Regards

Hao


>   };
>   
>   /* The alignment ensures 32-bit compatible interfaces are not broken */
> @@ -39,6 +40,7 @@ enum {
>   	ALLOCINFO_FILTER_FUNCTION,
>   	ALLOCINFO_FILTER_FILENAME,
>   	ALLOCINFO_FILTER_LINENO,
> +	ALLOCINFO_FILTER_INACCURATE,
>   	ALLOCINFO_FILTER_MIN_SIZE,
>   	ALLOCINFO_FILTER_MAX_SIZE,
>   	__ALLOCINFO_FILTER_LAST = ALLOCINFO_FILTER_MAX_SIZE
> @@ -48,6 +50,7 @@ enum {
>   #define ALLOCINFO_FILTER_MASK_FUNCTION		(1 << ALLOCINFO_FILTER_FUNCTION)
>   #define ALLOCINFO_FILTER_MASK_FILENAME		(1 << ALLOCINFO_FILTER_FILENAME)
>   #define ALLOCINFO_FILTER_MASK_LINENO		(1 << ALLOCINFO_FILTER_LINENO)
> +#define ALLOCINFO_FILTER_MASK_INACCURATE	(1 << ALLOCINFO_FILTER_INACCURATE)
>   #define ALLOCINFO_FILTER_MASK_MIN_SIZE		(1 << ALLOCINFO_FILTER_MIN_SIZE)
>   #define ALLOCINFO_FILTER_MASK_MAX_SIZE		(1 << ALLOCINFO_FILTER_MAX_SIZE)
>   
> diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> index ddc6946f56ab..cbcd12c4ef9c 100644
> --- a/lib/alloc_tag.c
> +++ b/lib/alloc_tag.c
> @@ -249,6 +249,8 @@ static bool matches_filter(struct codetag *ct, struct allocinfo_filter *filter,
>   			   struct alloc_tag_counters *counters,
>   			   bool *fetched_counters)
>   {
> +	bool inaccurate;
> +
>   	if (!filter || !filter->mask)
>   		return true;
>   
> @@ -275,6 +277,12 @@ static bool matches_filter(struct codetag *ct, struct allocinfo_filter *filter,
>   	    ct->lineno != filter->fields.lineno)
>   		return false;
>   
> +	if (filter->mask & ALLOCINFO_FILTER_MASK_INACCURATE) {
> +		inaccurate = !!(ct->flags & CODETAG_FLAG_INACCURATE);
> +		if (inaccurate != !!(filter->fields.inaccurate))
> +			return false;
> +	}
> +
>   	if (filter->mask & (ALLOCINFO_FILTER_MASK_MIN_SIZE | ALLOCINFO_FILTER_MASK_MAX_SIZE)) {
>   		if (!*fetched_counters) {
>   			*counters = allocinfo_prefetch_counters(ct);