[PATCH RESEND 0/2] net: cleanup bitmaps printing

[PATCH RESEND 0/2] net: cleanup bitmaps printing

[Yury Norov]

Bitmap API has a bitmap_print_to_pagebuf() function that is intended to
print bitmap into a human readable format, making sure that the output
string will not get big enough to cross the current page limit.

Some drivers use this function immediately before passing the result to
scnprintf() with no modification. This is useless because scnprintf(),
and helpers based on it like seq_pritf() and sysfs_emit(), take care of
not overflowing the buffer by itself, and perfectly print bitmaps with
"%*pb[l]".

This is a resend of networking part of [1]. Patch #2 switches from plain
scnprintf() to sysfs_emit, as pointed out by Thomas Weißschuh. 

[1] https://lore.kernel.org/all/20260219181407.290201-1-ynorov@nvidia.com/

Yury Norov (2):
  octeontx2-af: siplify rvu_debugfs
  net-sysfs: switch xps_queue_show() to sysfs_emit()

 .../marvell/octeontx2/af/rvu_debugfs.c        | 28 ++++---------------
 net/core/net-sysfs.c                          |  2 +-
 2 files changed, 6 insertions(+), 24 deletions(-)

-- 
2.43.0

[PATCH 1/2] octeontx2-af: siplify rvu_debugfs

[Yury Norov]

The driver uses bitmap_print_to_pagebuf() to store human-readable
bitmaps representations in a temporary buffers; and then feed
seq_printf() with it.

Switch to using seq_printf("%*pb") directly and drop intermediate
buffer.

Signed-off-by: Yury Norov <ynorov@nvidia.com>
---
 .../marvell/octeontx2/af/rvu_debugfs.c        | 28 ++++---------------
 1 file changed, 5 insertions(+), 23 deletions(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
index 15d3cb0b9da6..159b910eef84 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
@@ -960,30 +960,21 @@ static bool rvu_dbg_is_valid_lf(struct rvu *rvu, int blkaddr, int lf,
 
 static void print_npa_qsize(struct seq_file *m, struct rvu_pfvf *pfvf)
 {
-	char *buf;
-
-	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
-	if (!buf)
-		return;
-
 	if (!pfvf->aura_ctx) {
 		seq_puts(m, "Aura context is not initialized\n");
 	} else {
-		bitmap_print_to_pagebuf(false, buf, pfvf->aura_bmap,
-					pfvf->aura_ctx->qsize);
 		seq_printf(m, "Aura count : %d\n", pfvf->aura_ctx->qsize);
-		seq_printf(m, "Aura context ena/dis bitmap : %s\n", buf);
+		seq_printf(m, "Aura context ena/dis bitmap : %*pb\n",
+			   pfvf->aura_ctx->qsize, pfvf->aura_bmap);
 	}
 
 	if (!pfvf->pool_ctx) {
 		seq_puts(m, "Pool context is not initialized\n");
 	} else {
-		bitmap_print_to_pagebuf(false, buf, pfvf->pool_bmap,
-					pfvf->pool_ctx->qsize);
 		seq_printf(m, "Pool count : %d\n", pfvf->pool_ctx->qsize);
-		seq_printf(m, "Pool context ena/dis bitmap : %s\n", buf);
+		seq_printf(m, "Pool context ena/dis bitmap : %*pb\n",
+			   pfvf->aura_ctx->qsize, pfvf->aura_bmap);
 	}
-	kfree(buf);
 }
 
 /* The 'qsize' entry dumps current Aura/Pool context Qsize
@@ -2545,17 +2536,8 @@ RVU_DEBUG_SEQ_FOPS(nix_cq_ctx, nix_cq_ctx_display, nix_cq_ctx_write);
 static void print_nix_qctx_qsize(struct seq_file *filp, int qsize,
 				 unsigned long *bmap, char *qtype)
 {
-	char *buf;
-
-	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
-	if (!buf)
-		return;
-
-	bitmap_print_to_pagebuf(false, buf, bmap, qsize);
 	seq_printf(filp, "%s context count : %d\n", qtype, qsize);
-	seq_printf(filp, "%s context ena/dis bitmap : %s\n",
-		   qtype, buf);
-	kfree(buf);
+	seq_printf(filp, "%s context ena/dis bitmap : %*pb\n", qtype, qsize, bmap);
 }
 
 static void print_nix_qsize(struct seq_file *filp, struct rvu_pfvf *pfvf)
-- 
2.43.0

Re: [1/2] octeontx2-af: siplify rvu_debugfs

[Simon Horman]

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.

For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
---
octeontx2-af: siplify rvu_debugfs

The driver uses bitmap_print_to_pagebuf() to store human-readable
bitmaps representations in a temporary buffers; and then feed
seq_printf() with it. Switch to using seq_printf("%*pb") directly
and drop intermediate buffer.

> diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
> index 413f9fa40b33..cae61c4de47f 100644
> --- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
> +++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
> @@ -962,30 +962,21 @@ static bool rvu_dbg_is_valid_lf(struct rvu *rvu, int blkaddr, int lf,
>
>  static void print_npa_qsize(struct seq_file *m, struct rvu_pfvf *pfvf)
>  {
> -	char *buf;
> -
> -	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
> -	if (!buf)
> -		return;
> -
>  	if (!pfvf->aura_ctx) {
>  		seq_puts(m, "Aura context is not initialized\n");
>  	} else {
> -		bitmap_print_to_pagebuf(false, buf, pfvf->aura_bmap,
> -					pfvf->aura_ctx->qsize);
>  		seq_printf(m, "Aura count : %d\n", pfvf->aura_ctx->qsize);
> -		seq_printf(m, "Aura context ena/dis bitmap : %s\n", buf);
> +		seq_printf(m, "Aura context ena/dis bitmap : %*pb\n",
> +			   pfvf->aura_ctx->qsize, pfvf->aura_bmap);
>  	}
>
>  	if (!pfvf->pool_ctx) {
>  		seq_puts(m, "Pool context is not initialized\n");
>  	} else {
> -		bitmap_print_to_pagebuf(false, buf, pfvf->pool_bmap,
> -					pfvf->pool_ctx->qsize);
>  		seq_printf(m, "Pool count : %d\n", pfvf->pool_ctx->qsize);
> -		seq_printf(m, "Pool context ena/dis bitmap : %s\n", buf);
> +		seq_printf(m, "Pool context ena/dis bitmap : %*pb\n",
> +			   pfvf->aura_ctx->qsize, pfvf->aura_bmap);
                   ^^^^^^^^^^^^^^^^^^^^  ^^^^^^^^^^^^^^^^

Does this code have a copy-paste error? The pool context output is
displaying the aura bitmap instead of the pool bitmap.

The old code correctly used pfvf->pool_bmap and pfvf->pool_ctx->qsize:

    bitmap_print_to_pagebuf(false, buf, pfvf->pool_bmap,
                            pfvf->pool_ctx->qsize);

But the new code uses pfvf->aura_bmap and pfvf->aura_ctx->qsize for
both the aura and pool context displays. This makes the pool context
debugfs output show incorrect information.

>  	}
> -	kfree(buf);
>  }

[ ... ]

Re: [PATCH 1/2] octeontx2-af: siplify rvu_debugfs

[Jakub Kicinski]

On Tue,  3 Mar 2026 13:55:05 -0500 Yury Norov wrote:
> Subject: [PATCH 1/2] octeontx2-af: siplify rvu_debugfs

when you respin - please also fix the typo in the subject

[PATCH 2/2] net-sysfs: switch xps_queue_show() to sysfs_emit()

[Yury Norov]

Switch the function to use the proper sysfs_emit("%pb").

Suggested-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Yury Norov <ynorov@nvidia.com>
---
 net/core/net-sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 07624b682b08..a260f8b4d5c6 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1754,7 +1754,7 @@ static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
 out_no_maps:
 	rcu_read_unlock();
 
-	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
+	len = sysfs_emit(buf, "%*pb\n", nr_ids, mask);
 	bitmap_free(mask);
 
 	return len < PAGE_SIZE ? len : -EINVAL;
-- 
2.43.0

Re: [PATCH 2/2] net-sysfs: switch xps_queue_show() to sysfs_emit()

[Thomas Weißschuh]

On 2026-03-03 13:55:06-0500, Yury Norov wrote:
> Switch the function to use the proper sysfs_emit("%pb").
> 
> Suggested-by: Thomas Weißschuh <linux@weissschuh.net>
> Signed-off-by: Yury Norov <ynorov@nvidia.com>

Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>

> ---
>  net/core/net-sysfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index 07624b682b08..a260f8b4d5c6 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -1754,7 +1754,7 @@ static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
>  out_no_maps:
>  	rcu_read_unlock();
>  
> -	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
> +	len = sysfs_emit(buf, "%*pb\n", nr_ids, mask);
>  	bitmap_free(mask);
>  
>  	return len < PAGE_SIZE ? len : -EINVAL;

[PATCH v2 0/2] net: cleanup bitmaps printing

[Yury Norov]

Bitmap API has a bitmap_print_to_pagebuf() function that is intended to
print bitmap into a human readable format, making sure that the output
string will not get big enough to cross the current page limit.

Some drivers use this function immediately before passing the result to
scnprintf() with no modification. This is useless because scnprintf(),
and helpers based on it like seq_pritf() and sysfs_emit(), take care of
not overflowing the buffer by itself, and perfectly print bitmaps with
"%*pb[l]".

v1: https://lore.kernel.org/all/20260219181407.290201-1-ynorov@nvidia.com/
v2:
 - fix copy-paste error in print_npa_qsize() (Simon);
 - fix typo in #1 subject (Jakub).

Yury Norov (2):
  octeontx2-af: siplify rvu_debugfs
  net-sysfs: switch xps_queue_show() to sysfs_emit()

 .../marvell/octeontx2/af/rvu_debugfs.c        | 28 ++++---------------
 net/core/net-sysfs.c                          |  2 +-
 2 files changed, 6 insertions(+), 24 deletions(-)

-- 
2.43.0

[PATCH 2/2] net-sysfs: switch xps_queue_show() to sysfs_emit()

[Yury Norov]

Switch the function to use the proper sysfs_emit("%pb").

Suggested-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Yury Norov <ynorov@nvidia.com>
---
 net/core/net-sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 07624b682b08..a260f8b4d5c6 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1754,7 +1754,7 @@ static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
 out_no_maps:
 	rcu_read_unlock();
 
-	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
+	len = sysfs_emit(buf, "%*pb\n", nr_ids, mask);
 	bitmap_free(mask);
 
 	return len < PAGE_SIZE ? len : -EINVAL;
-- 
2.43.0