[PATCH v2] octeontx2-af: use seq_file for rsrc_alloc debugfs

[Heyang Tan]

The rsrc_alloc debugfs reader writes rows directly to userspace without
respecting the caller's read count. It also uses the current row length as
the userspace stride, which can corrupt output when rows have different
widths.

Use seq_file to handle userspace buffer sizes, offsets, and partial reads,
and write output columns directly to the seq_file buffer.

Fixes: 23205e6d06d4 ("octeontx2-af: Dump current resource provisioning status")
Signed-off-by: Heyang Tan <thy15333007817@xxxxxxx>
---
Changes in v2:
- Write columns directly to the seq_file buffer as suggested by Ratheesh.
- Preserve skipping PF/VF rows without allocated resources.

Link: https://lore.kernel.org/netdev/20260906141129.1730-1-thy15333007817@xxxxxxx/
Compile-tested: drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.o
Not hardware-tested.

 .../marvell/octeontx2/af/rvu_debugfs.c        | 104 ++++++------------
 1 file changed, 33 insertions(+), 71 deletions(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
index 22ee99676879..fcbf4ba0e10a 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.c
@@ -714,110 +714,72 @@ static int get_max_column_width(struct rvu *rvu)
 }
 
 /* Dumps current provisioning status of all RVU block LFs */
-static ssize_t rvu_dbg_rsrc_attach_status(struct file *filp,
-					  char __user *buffer,
-					  size_t count, loff_t *ppos)
+static int rvu_dbg_rsrc_attach_status(struct seq_file *filp, void *unused)
 {
-	int index, off = 0, flag = 0, len = 0, i = 0;
-	struct rvu *rvu = filp->private_data;
-	int bytes_not_copied = 0;
+	int index, pf, vf, pcifunc;
+	struct rvu *rvu = filp->private;
 	struct rvu_block block;
-	int pf, vf, pcifunc;
-	int buf_size = 2048;
 	int lf_str_size;
 	char *lfs;
-	char *buf;
-
-	/* don't allow partial reads */
-	if (*ppos != 0)
-		return 0;
-
-	buf = kzalloc(buf_size, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
 
-	/* Get the maximum width of a column */
 	lf_str_size = get_max_column_width(rvu);
+	if (lf_str_size < 0)
+		return lf_str_size;
 
 	lfs = kzalloc(lf_str_size, GFP_KERNEL);
-	if (!lfs) {
-		kfree(buf);
+	if (!lfs)
 		return -ENOMEM;
-	}
-	off +=	scnprintf(&buf[off], buf_size - 1 - off, "%-*s", lf_str_size,
-			  "pcifunc");
-	for (index = 0; index < BLK_COUNT; index++)
-		if (strlen(rvu->hw->block[index].name)) {
-			off += scnprintf(&buf[off], buf_size - 1 - off,
-					 "%-*s", lf_str_size,
-					 rvu->hw->block[index].name);
-		}
 
-	off += scnprintf(&buf[off], buf_size - 1 - off, "\n");
-	bytes_not_copied = copy_to_user(buffer + (i * off), buf, off);
-	if (bytes_not_copied)
-		goto out;
+	seq_printf(filp, "%-*s", lf_str_size, "pcifunc");
+	for (index = 0; index < BLK_COUNT; index++)
+		if (strlen(rvu->hw->block[index].name))
+			seq_printf(filp, "%-*s", lf_str_size,
+				   rvu->hw->block[index].name);
 
-	i++;
-	*ppos += off;
+	seq_putc(filp, '\n');
 	for (pf = 0; pf < rvu->hw->total_pfs; pf++) {
 		for (vf = 0; vf <= rvu->hw->total_vfs; vf++) {
-			off = 0;
-			flag = 0;
 			pcifunc = rvu_make_pcifunc(rvu->pdev, pf, vf);
 			if (!pcifunc)
 				continue;
 
-			if (vf) {
+			for (index = 0; index < BLK_COUNT; index++) {
+				block = rvu->hw->block[index];
+				if (!strlen(block.name))
+					continue;
+				lfs[0] = '\0';
+				get_lf_str_list(&block, pcifunc, lfs);
+				if (strlen(lfs))
+					break;
+			}
+			if (index == BLK_COUNT)
+				continue;
+
+			if (vf)
 				sprintf(lfs, "PF%d:VF%d", pf, vf - 1);
-				off = scnprintf(&buf[off],
-						buf_size - 1 - off,
-						"%-*s", lf_str_size, lfs);
-			} else {
+			else
 				sprintf(lfs, "PF%d", pf);
-				off = scnprintf(&buf[off],
-						buf_size - 1 - off,
-						"%-*s", lf_str_size, lfs);
-			}
+			seq_printf(filp, "%-*s", lf_str_size, lfs);
 
 			for (index = 0; index < BLK_COUNT; index++) {
 				block = rvu->hw->block[index];
 				if (!strlen(block.name))
 					continue;
-				len = 0;
-				lfs[len] = '\0';
-				get_lf_str_list(&block, pcifunc, lfs);
-				if (strlen(lfs))
-					flag = 1;
 
-				off += scnprintf(&buf[off], buf_size - 1 - off,
-						 "%-*s", lf_str_size, lfs);
-			}
-			if (flag) {
-				off +=	scnprintf(&buf[off],
-						  buf_size - 1 - off, "\n");
-				bytes_not_copied = copy_to_user(buffer +
-								(i * off),
-								buf, off);
-				if (bytes_not_copied)
-					goto out;
-
-				i++;
-				*ppos += off;
+				lfs[0] = '\0';
+				get_lf_str_list(&block, pcifunc, lfs);
+				seq_printf(filp, "%-*s", lf_str_size, lfs);
 			}
+			seq_putc(filp, '\n');
 		}
 	}
 
-out:
 	kfree(lfs);
-	kfree(buf);
-	if (bytes_not_copied)
-		return -EFAULT;
 
-	return *ppos;
+	return 0;
 }
 
-RVU_DEBUG_FOPS(rsrc_status, rsrc_attach_status, NULL);
+RVU_DEBUG_SEQ_FOPS(rsrc_status, rsrc_attach_status, NULL);
 
 static int rvu_dbg_rvu_pf_cgx_map_display(struct seq_file *filp, void *unused)
 {
-- 
2.34.1