netdev - [PATCH net-next v3 10/10] ptp: ocp: change sysfs attr group handling

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Date:   Fri, 13 May 2022 15:59:24 -0700
From:   Jonathan Lemon <jonathan.lemon@...il.com>
To:     netdev@...r.kernel.org
Cc:     richardcochran@...il.com, davem@...emloft.net, kuba@...nel.org,
        pabeni@...hat.com, edumazet@...gle.com, kernel-team@...com
Subject: [PATCH net-next v3 10/10] ptp: ocp: change sysfs attr group handling

In the detach path, the driver calls sysfs_remove_group() for the
groups it believes has been registered.  However, if the group was
never previously registered, then this causes a splat.

Instead, compute the groups that should be registered in advance,
and then use sysfs_create_groups(), which registers them all at once.
Update the error handling appropriately.

Reported-by: Zheyu Ma <zheyuma97@...il.com>
Signed-off-by: Jonathan Lemon <jonathan.lemon@...il.com>
---
 drivers/ptp/ptp_ocp.c | 67 ++++++++++++++++++++++++++++++++++---------
 1 file changed, 53 insertions(+), 14 deletions(-)

diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
index 4ff7f16242cf..6772b1e7e6d2 100644
--- a/drivers/ptp/ptp_ocp.c
+++ b/drivers/ptp/ptp_ocp.c
@@ -321,7 +321,7 @@ struct ptp_ocp {
 	struct platform_device	*spi_flash;
 	struct clk_hw		*i2c_clk;
 	struct timer_list	watchdog;
-	const struct ocp_attr_group *attr_tbl;
+	const struct attribute_group **attr_group;
 	const struct ptp_ocp_eeprom_map *eeprom_map;
 	struct dentry		*debug_root;
 	time64_t		gnss_lost;
@@ -1946,6 +1946,30 @@ ptp_ocp_signal_init(struct ptp_ocp *bp)
 					     bp->signal_out[i]->mem);
 }
 
+static int
+ptp_ocp_build_attr_group(struct ptp_ocp *bp,
+			 const struct ocp_attr_group *attr_tbl)
+{
+	int count, i;
+
+	count = 0;
+	for (i = 0; attr_tbl[i].cap; i++)
+		if (attr_tbl[i].cap & bp->fw_cap)
+			count++;
+
+	bp->attr_group = kcalloc(count + 1, sizeof(struct attribute_group *),
+				 GFP_KERNEL);
+	if (!bp->attr_group)
+		return -ENOMEM;
+
+	count = 0;
+	for (i = 0; attr_tbl[i].cap; i++)
+		if (attr_tbl[i].cap & bp->fw_cap)
+			bp->attr_group[count++] = attr_tbl[i].group;
+
+	return 0;
+}
+
 static void
 ptp_ocp_enable_fpga(u32 __iomem *reg, u32 bit, bool enable)
 {
@@ -2184,7 +2208,6 @@ ptp_ocp_fb_board_init(struct ptp_ocp *bp, struct ocp_resource *r)
 	bp->flash_start = 1024 * 4096;
 	bp->eeprom_map = fb_eeprom_map;
 	bp->fw_version = ioread32(&bp->image->version);
-	bp->attr_tbl = fb_timecard_groups;
 	bp->sma_op = &ocp_fb_sma_op;
 
 	ptp_ocp_fb_set_version(bp);
@@ -2194,6 +2217,10 @@ ptp_ocp_fb_board_init(struct ptp_ocp *bp, struct ocp_resource *r)
 	ptp_ocp_sma_init(bp);
 	ptp_ocp_signal_init(bp);
 
+	err = ptp_ocp_build_attr_group(bp, fb_timecard_groups);
+	if (err)
+		return err;
+
 	err = ptp_ocp_fb_set_pins(bp);
 	if (err)
 		return err;
@@ -3539,12 +3566,31 @@ ptp_ocp_link_child(struct ptp_ocp *bp, const char *name, const char *link)
 	put_device(child);
 }
 
+static void
+ptp_ocp_attr_group_del(struct ptp_ocp *bp)
+{
+	sysfs_remove_groups(&bp->dev.kobj, bp->attr_group);
+	kfree(bp->attr_group);
+}
+
+static int
+ptp_ocp_attr_group_add(struct ptp_ocp *bp)
+{
+	int err;
+
+	err = sysfs_create_groups(&bp->dev.kobj, bp->attr_group);
+	if (err)
+		bp->attr_group[0] = NULL;
+
+	return err;
+}
+
 static int
 ptp_ocp_complete(struct ptp_ocp *bp)
 {
 	struct pps_device *pps;
 	char buf[32];
-	int i, err;
+	int err;
 
 	if (bp->gnss_port != -1) {
 		sprintf(buf, "ttyS%d", bp->gnss_port);
@@ -3569,13 +3615,9 @@ ptp_ocp_complete(struct ptp_ocp *bp)
 	if (pps)
 		ptp_ocp_symlink(bp, pps->dev, "pps");
 
-	for (i = 0; bp->attr_tbl[i].cap; i++) {
-		if (!(bp->attr_tbl[i].cap & bp->fw_cap))
-			continue;
-		err = sysfs_create_group(&bp->dev.kobj, bp->attr_tbl[i].group);
-		if (err)
-			return err;
-	}
+	err = ptp_ocp_attr_group_add(bp);
+	if (err)
+		return err;
 
 	ptp_ocp_debugfs_add_device(bp);
 
@@ -3640,15 +3682,11 @@ static void
 ptp_ocp_detach_sysfs(struct ptp_ocp *bp)
 {
 	struct device *dev = &bp->dev;
-	int i;
 
 	sysfs_remove_link(&dev->kobj, "ttyGNSS");
 	sysfs_remove_link(&dev->kobj, "ttyMAC");
 	sysfs_remove_link(&dev->kobj, "ptp");
 	sysfs_remove_link(&dev->kobj, "pps");
-	if (bp->attr_tbl)
-		for (i = 0; bp->attr_tbl[i].cap; i++)
-			sysfs_remove_group(&dev->kobj, bp->attr_tbl[i].group);
 }
 
 static void
@@ -3658,6 +3696,7 @@ ptp_ocp_detach(struct ptp_ocp *bp)
 
 	ptp_ocp_debugfs_remove_device(bp);
 	ptp_ocp_detach_sysfs(bp);
+	ptp_ocp_attr_group_del(bp);
 	if (timer_pending(&bp->watchdog))
 		del_timer_sync(&bp->watchdog);
 	if (bp->ts0)
-- 
2.31.1