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

[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 1/2] octeontx2-af: simplify 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..9e5a85998ccc 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->pool_ctx->qsize, pfvf->pool_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

[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

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

[Simon Horman]

On Thu, Mar 19, 2026 at 04:17:09PM -0400, Yury Norov wrote:
> 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).

Thanks for the updates.

Reviewed-by: Simon Horman <horms@kernel.org>

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

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Thu, 19 Mar 2026 16:17:09 -0400 you wrote:
> 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]".
> 
> [...]

Here is the summary with links:
  - [1/2] octeontx2-af: simplify rvu_debugfs
    https://git.kernel.org/netdev/net-next/c/6e4235adfa88
  - [2/2] net-sysfs: switch xps_queue_show() to sysfs_emit()
    https://git.kernel.org/netdev/net-next/c/de69301dc2f6

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html