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[PATCH net-next] net: bridge: use sysfs_emit instead of sprintf

David Corvaglia posted 1 patch 6 days, 12 hours ago
There is a newer version of this series
net/bridge/br_stp_if.c   |  2 +-
net/bridge/br_sysfs_br.c | 84 ++++++++++++++++++++--------------------
net/bridge/br_sysfs_if.c | 32 +++++++--------
3 files changed, 59 insertions(+), 59 deletions(-)
[PATCH net-next] net: bridge: use sysfs_emit instead of sprintf
Posted by David Corvaglia 6 days, 12 hours ago 
Replace sprintf with sysfs_emit in sysfs show() methods as outlined in
Documentation/filesystems/sysfs.rst. sysfs_emit is preferred to sprintf 
in sysfs show() methods as it is safer with buffer handling.

Signed-off-by: David Corvaglia <david@corvaglia.dev>
---
This is my first patch to the kernel! I've been able to build and boot 
with the patch. I also tested the sysfs reads and they seem to be 
correct. Any feedback is appreciated.

 net/bridge/br_stp_if.c   |  2 +-
 net/bridge/br_sysfs_br.c | 84 ++++++++++++++++++++--------------------
 net/bridge/br_sysfs_if.c | 32 +++++++--------
 3 files changed, 59 insertions(+), 59 deletions(-)

diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index c20a41bf253b..aad338706c6d 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -344,7 +344,7 @@ int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
 
 ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
 {
-	return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
+	return sysfs_emit(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
 	       id->prio[0], id->prio[1],
 	       id->addr[0], id->addr[1], id->addr[2],
 	       id->addr[3], id->addr[4], id->addr[5]);
diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index cb4855ed9500..74ffa2176784 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c
@@ -67,7 +67,7 @@ static ssize_t forward_delay_show(struct device *d,
 				  struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%lu\n", jiffies_to_clock_t(br->forward_delay));
+	return sysfs_emit(buf, "%lu\n", jiffies_to_clock_t(br->forward_delay));
 }
 
 static int set_forward_delay(struct net_bridge *br, unsigned long val,
@@ -87,7 +87,7 @@ static DEVICE_ATTR_RW(forward_delay);
 static ssize_t hello_time_show(struct device *d, struct device_attribute *attr,
 			       char *buf)
 {
-	return sprintf(buf, "%lu\n",
+	return sysfs_emit(buf, "%lu\n",
 		       jiffies_to_clock_t(to_bridge(d)->hello_time));
 }
 
@@ -108,7 +108,7 @@ static DEVICE_ATTR_RW(hello_time);
 static ssize_t max_age_show(struct device *d, struct device_attribute *attr,
 			    char *buf)
 {
-	return sprintf(buf, "%lu\n",
+	return sysfs_emit(buf, "%lu\n",
 		       jiffies_to_clock_t(to_bridge(d)->max_age));
 }
 
@@ -129,7 +129,7 @@ static ssize_t ageing_time_show(struct device *d,
 				struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%lu\n", jiffies_to_clock_t(br->ageing_time));
+	return sysfs_emit(buf, "%lu\n", jiffies_to_clock_t(br->ageing_time));
 }
 
 static int set_ageing_time(struct net_bridge *br, unsigned long val,
@@ -150,7 +150,7 @@ static ssize_t stp_state_show(struct device *d,
 			      struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%d\n", br->stp_enabled);
+	return sysfs_emit(buf, "%d\n", br->stp_enabled);
 }
 
 
@@ -173,7 +173,7 @@ static ssize_t group_fwd_mask_show(struct device *d,
 				   char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%#x\n", br->group_fwd_mask);
+	return sysfs_emit(buf, "%#x\n", br->group_fwd_mask);
 }
 
 static int set_group_fwd_mask(struct net_bridge *br, unsigned long val,
@@ -200,7 +200,7 @@ static ssize_t priority_show(struct device *d, struct device_attribute *attr,
 			     char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%d\n",
+	return sysfs_emit(buf, "%d\n",
 		       (br->bridge_id.prio[0] << 8) | br->bridge_id.prio[1]);
 }
 
@@ -235,21 +235,21 @@ static DEVICE_ATTR_RO(bridge_id);
 static ssize_t root_port_show(struct device *d, struct device_attribute *attr,
 			      char *buf)
 {
-	return sprintf(buf, "%d\n", to_bridge(d)->root_port);
+	return sysfs_emit(buf, "%d\n", to_bridge(d)->root_port);
 }
 static DEVICE_ATTR_RO(root_port);
 
 static ssize_t root_path_cost_show(struct device *d,
 				   struct device_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%d\n", to_bridge(d)->root_path_cost);
+	return sysfs_emit(buf, "%d\n", to_bridge(d)->root_path_cost);
 }
 static DEVICE_ATTR_RO(root_path_cost);
 
 static ssize_t topology_change_show(struct device *d,
 				    struct device_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%d\n", to_bridge(d)->topology_change);
+	return sysfs_emit(buf, "%d\n", to_bridge(d)->topology_change);
 }
 static DEVICE_ATTR_RO(topology_change);
 
@@ -258,7 +258,7 @@ static ssize_t topology_change_detected_show(struct device *d,
 					     char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%d\n", br->topology_change_detected);
+	return sysfs_emit(buf, "%d\n", br->topology_change_detected);
 }
 static DEVICE_ATTR_RO(topology_change_detected);
 
@@ -266,7 +266,7 @@ static ssize_t hello_timer_show(struct device *d,
 				struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%ld\n", br_timer_value(&br->hello_timer));
+	return sysfs_emit(buf, "%ld\n", br_timer_value(&br->hello_timer));
 }
 static DEVICE_ATTR_RO(hello_timer);
 
@@ -274,7 +274,7 @@ static ssize_t tcn_timer_show(struct device *d, struct device_attribute *attr,
 			      char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%ld\n", br_timer_value(&br->tcn_timer));
+	return sysfs_emit(buf, "%ld\n", br_timer_value(&br->tcn_timer));
 }
 static DEVICE_ATTR_RO(tcn_timer);
 
@@ -283,7 +283,7 @@ static ssize_t topology_change_timer_show(struct device *d,
 					  char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%ld\n", br_timer_value(&br->topology_change_timer));
+	return sysfs_emit(buf, "%ld\n", br_timer_value(&br->topology_change_timer));
 }
 static DEVICE_ATTR_RO(topology_change_timer);
 
@@ -291,7 +291,7 @@ static ssize_t gc_timer_show(struct device *d, struct device_attribute *attr,
 			     char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%ld\n", br_timer_value(&br->gc_work.timer));
+	return sysfs_emit(buf, "%ld\n", br_timer_value(&br->gc_work.timer));
 }
 static DEVICE_ATTR_RO(gc_timer);
 
@@ -299,7 +299,7 @@ static ssize_t group_addr_show(struct device *d,
 			       struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%pM\n", br->group_addr);
+	return sysfs_emit(buf, "%pM\n", br->group_addr);
 }
 
 static ssize_t group_addr_store(struct device *d,
@@ -365,7 +365,7 @@ static ssize_t no_linklocal_learn_show(struct device *d,
 				       char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%d\n", br_boolopt_get(br, BR_BOOLOPT_NO_LL_LEARN));
+	return sysfs_emit(buf, "%d\n", br_boolopt_get(br, BR_BOOLOPT_NO_LL_LEARN));
 }
 
 static int set_no_linklocal_learn(struct net_bridge *br, unsigned long val,
@@ -387,7 +387,7 @@ static ssize_t multicast_router_show(struct device *d,
 				     struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%d\n", br->multicast_ctx.multicast_router);
+	return sysfs_emit(buf, "%d\n", br->multicast_ctx.multicast_router);
 }
 
 static int set_multicast_router(struct net_bridge *br, unsigned long val,
@@ -409,7 +409,7 @@ static ssize_t multicast_snooping_show(struct device *d,
 				       char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%d\n", br_opt_get(br, BROPT_MULTICAST_ENABLED));
+	return sysfs_emit(buf, "%d\n", br_opt_get(br, BROPT_MULTICAST_ENABLED));
 }
 
 static ssize_t multicast_snooping_store(struct device *d,
@@ -425,7 +425,7 @@ static ssize_t multicast_query_use_ifaddr_show(struct device *d,
 					       char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%d\n",
+	return sysfs_emit(buf, "%d\n",
 		       br_opt_get(br, BROPT_MULTICAST_QUERY_USE_IFADDR));
 }
 
@@ -450,7 +450,7 @@ static ssize_t multicast_querier_show(struct device *d,
 				      char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%d\n", br->multicast_ctx.multicast_querier);
+	return sysfs_emit(buf, "%d\n", br->multicast_ctx.multicast_querier);
 }
 
 static int set_multicast_querier(struct net_bridge *br, unsigned long val,
@@ -470,7 +470,7 @@ static DEVICE_ATTR_RW(multicast_querier);
 static ssize_t hash_elasticity_show(struct device *d,
 				    struct device_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%u\n", RHT_ELASTICITY);
+	return sysfs_emit(buf, "%u\n", RHT_ELASTICITY);
 }
 
 static int set_elasticity(struct net_bridge *br, unsigned long val,
@@ -494,7 +494,7 @@ static ssize_t hash_max_show(struct device *d, struct device_attribute *attr,
 			     char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%u\n", br->hash_max);
+	return sysfs_emit(buf, "%u\n", br->hash_max);
 }
 
 static int set_hash_max(struct net_bridge *br, unsigned long val,
@@ -517,7 +517,7 @@ static ssize_t multicast_igmp_version_show(struct device *d,
 {
 	struct net_bridge *br = to_bridge(d);
 
-	return sprintf(buf, "%u\n", br->multicast_ctx.multicast_igmp_version);
+	return sysfs_emit(buf, "%u\n", br->multicast_ctx.multicast_igmp_version);
 }
 
 static int set_multicast_igmp_version(struct net_bridge *br, unsigned long val,
@@ -539,7 +539,7 @@ static ssize_t multicast_last_member_count_show(struct device *d,
 						char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%u\n", br->multicast_ctx.multicast_last_member_count);
+	return sysfs_emit(buf, "%u\n", br->multicast_ctx.multicast_last_member_count);
 }
 
 static int set_last_member_count(struct net_bridge *br, unsigned long val,
@@ -561,7 +561,7 @@ static ssize_t multicast_startup_query_count_show(
 	struct device *d, struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%u\n", br->multicast_ctx.multicast_startup_query_count);
+	return sysfs_emit(buf, "%u\n", br->multicast_ctx.multicast_startup_query_count);
 }
 
 static int set_startup_query_count(struct net_bridge *br, unsigned long val,
@@ -583,7 +583,7 @@ static ssize_t multicast_last_member_interval_show(
 	struct device *d, struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%lu\n",
+	return sysfs_emit(buf, "%lu\n",
 		       jiffies_to_clock_t(br->multicast_ctx.multicast_last_member_interval));
 }
 
@@ -606,7 +606,7 @@ static ssize_t multicast_membership_interval_show(
 	struct device *d, struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%lu\n",
+	return sysfs_emit(buf, "%lu\n",
 		       jiffies_to_clock_t(br->multicast_ctx.multicast_membership_interval));
 }
 
@@ -630,7 +630,7 @@ static ssize_t multicast_querier_interval_show(struct device *d,
 					       char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%lu\n",
+	return sysfs_emit(buf, "%lu\n",
 		       jiffies_to_clock_t(br->multicast_ctx.multicast_querier_interval));
 }
 
@@ -654,7 +654,7 @@ static ssize_t multicast_query_interval_show(struct device *d,
 					     char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%lu\n",
+	return sysfs_emit(buf, "%lu\n",
 		       jiffies_to_clock_t(br->multicast_ctx.multicast_query_interval));
 }
 
@@ -677,7 +677,7 @@ static ssize_t multicast_query_response_interval_show(
 	struct device *d, struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(
+	return sysfs_emit(
 		buf, "%lu\n",
 		jiffies_to_clock_t(br->multicast_ctx.multicast_query_response_interval));
 }
@@ -701,7 +701,7 @@ static ssize_t multicast_startup_query_interval_show(
 	struct device *d, struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(
+	return sysfs_emit(
 		buf, "%lu\n",
 		jiffies_to_clock_t(br->multicast_ctx.multicast_startup_query_interval));
 }
@@ -727,7 +727,7 @@ static ssize_t multicast_stats_enabled_show(struct device *d,
 {
 	struct net_bridge *br = to_bridge(d);
 
-	return sprintf(buf, "%d\n",
+	return sysfs_emit(buf, "%d\n",
 		       br_opt_get(br, BROPT_MULTICAST_STATS_ENABLED));
 }
 
@@ -754,7 +754,7 @@ static ssize_t multicast_mld_version_show(struct device *d,
 {
 	struct net_bridge *br = to_bridge(d);
 
-	return sprintf(buf, "%u\n", br->multicast_ctx.multicast_mld_version);
+	return sysfs_emit(buf, "%u\n", br->multicast_ctx.multicast_mld_version);
 }
 
 static int set_multicast_mld_version(struct net_bridge *br, unsigned long val,
@@ -777,7 +777,7 @@ static ssize_t nf_call_iptables_show(
 	struct device *d, struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%u\n", br_opt_get(br, BROPT_NF_CALL_IPTABLES));
+	return sysfs_emit(buf, "%u\n", br_opt_get(br, BROPT_NF_CALL_IPTABLES));
 }
 
 static int set_nf_call_iptables(struct net_bridge *br, unsigned long val,
@@ -799,7 +799,7 @@ static ssize_t nf_call_ip6tables_show(
 	struct device *d, struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%u\n", br_opt_get(br, BROPT_NF_CALL_IP6TABLES));
+	return sysfs_emit(buf, "%u\n", br_opt_get(br, BROPT_NF_CALL_IP6TABLES));
 }
 
 static int set_nf_call_ip6tables(struct net_bridge *br, unsigned long val,
@@ -821,7 +821,7 @@ static ssize_t nf_call_arptables_show(
 	struct device *d, struct device_attribute *attr, char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%u\n", br_opt_get(br, BROPT_NF_CALL_ARPTABLES));
+	return sysfs_emit(buf, "%u\n", br_opt_get(br, BROPT_NF_CALL_ARPTABLES));
 }
 
 static int set_nf_call_arptables(struct net_bridge *br, unsigned long val,
@@ -845,7 +845,7 @@ static ssize_t vlan_filtering_show(struct device *d,
 				   char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%d\n", br_opt_get(br, BROPT_VLAN_ENABLED));
+	return sysfs_emit(buf, "%d\n", br_opt_get(br, BROPT_VLAN_ENABLED));
 }
 
 static ssize_t vlan_filtering_store(struct device *d,
@@ -861,7 +861,7 @@ static ssize_t vlan_protocol_show(struct device *d,
 				  char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%#06x\n", ntohs(br->vlan_proto));
+	return sysfs_emit(buf, "%#06x\n", ntohs(br->vlan_proto));
 }
 
 static ssize_t vlan_protocol_store(struct device *d,
@@ -877,7 +877,7 @@ static ssize_t default_pvid_show(struct device *d,
 				 char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%d\n", br->default_pvid);
+	return sysfs_emit(buf, "%d\n", br->default_pvid);
 }
 
 static ssize_t default_pvid_store(struct device *d,
@@ -893,7 +893,7 @@ static ssize_t vlan_stats_enabled_show(struct device *d,
 				       char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%u\n", br_opt_get(br, BROPT_VLAN_STATS_ENABLED));
+	return sysfs_emit(buf, "%u\n", br_opt_get(br, BROPT_VLAN_STATS_ENABLED));
 }
 
 static int set_vlan_stats_enabled(struct net_bridge *br, unsigned long val,
@@ -915,7 +915,7 @@ static ssize_t vlan_stats_per_port_show(struct device *d,
 					char *buf)
 {
 	struct net_bridge *br = to_bridge(d);
-	return sprintf(buf, "%u\n", br_opt_get(br, BROPT_VLAN_STATS_PER_PORT));
+	return sysfs_emit(buf, "%u\n", br_opt_get(br, BROPT_VLAN_STATS_PER_PORT));
 }
 
 static int set_vlan_stats_per_port(struct net_bridge *br, unsigned long val,
diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
index 74fdd8105dca..1f57c36a7fc0 100644
--- a/net/bridge/br_sysfs_if.c
+++ b/net/bridge/br_sysfs_if.c
@@ -47,7 +47,7 @@ const struct brport_attribute brport_attr_##_name = { 	        \
 #define BRPORT_ATTR_FLAG(_name, _mask)				\
 static ssize_t show_##_name(struct net_bridge_port *p, char *buf) \
 {								\
-	return sprintf(buf, "%d\n", !!(p->flags & _mask));	\
+	return sysfs_emit(buf, "%d\n", !!(p->flags & _mask));	\
 }								\
 static int store_##_name(struct net_bridge_port *p, unsigned long v) \
 {								\
@@ -83,7 +83,7 @@ static int store_flag(struct net_bridge_port *p, unsigned long v,
 
 static ssize_t show_path_cost(struct net_bridge_port *p, char *buf)
 {
-	return sprintf(buf, "%d\n", p->path_cost);
+	return sysfs_emit(buf, "%d\n", p->path_cost);
 }
 
 static BRPORT_ATTR(path_cost, 0644,
@@ -91,7 +91,7 @@ static BRPORT_ATTR(path_cost, 0644,
 
 static ssize_t show_priority(struct net_bridge_port *p, char *buf)
 {
-	return sprintf(buf, "%d\n", p->priority);
+	return sysfs_emit(buf, "%d\n", p->priority);
 }
 
 static BRPORT_ATTR(priority, 0644,
@@ -111,65 +111,65 @@ static BRPORT_ATTR(designated_bridge, 0444, show_designated_bridge, NULL);
 
 static ssize_t show_designated_port(struct net_bridge_port *p, char *buf)
 {
-	return sprintf(buf, "%d\n", p->designated_port);
+	return sysfs_emit(buf, "%d\n", p->designated_port);
 }
 static BRPORT_ATTR(designated_port, 0444, show_designated_port, NULL);
 
 static ssize_t show_designated_cost(struct net_bridge_port *p, char *buf)
 {
-	return sprintf(buf, "%d\n", p->designated_cost);
+	return sysfs_emit(buf, "%d\n", p->designated_cost);
 }
 static BRPORT_ATTR(designated_cost, 0444, show_designated_cost, NULL);
 
 static ssize_t show_port_id(struct net_bridge_port *p, char *buf)
 {
-	return sprintf(buf, "0x%x\n", p->port_id);
+	return sysfs_emit(buf, "0x%x\n", p->port_id);
 }
 static BRPORT_ATTR(port_id, 0444, show_port_id, NULL);
 
 static ssize_t show_port_no(struct net_bridge_port *p, char *buf)
 {
-	return sprintf(buf, "0x%x\n", p->port_no);
+	return sysfs_emit(buf, "0x%x\n", p->port_no);
 }
 
 static BRPORT_ATTR(port_no, 0444, show_port_no, NULL);
 
 static ssize_t show_change_ack(struct net_bridge_port *p, char *buf)
 {
-	return sprintf(buf, "%d\n", p->topology_change_ack);
+	return sysfs_emit(buf, "%d\n", p->topology_change_ack);
 }
 static BRPORT_ATTR(change_ack, 0444, show_change_ack, NULL);
 
 static ssize_t show_config_pending(struct net_bridge_port *p, char *buf)
 {
-	return sprintf(buf, "%d\n", p->config_pending);
+	return sysfs_emit(buf, "%d\n", p->config_pending);
 }
 static BRPORT_ATTR(config_pending, 0444, show_config_pending, NULL);
 
 static ssize_t show_port_state(struct net_bridge_port *p, char *buf)
 {
-	return sprintf(buf, "%d\n", p->state);
+	return sysfs_emit(buf, "%d\n", p->state);
 }
 static BRPORT_ATTR(state, 0444, show_port_state, NULL);
 
 static ssize_t show_message_age_timer(struct net_bridge_port *p,
 					    char *buf)
 {
-	return sprintf(buf, "%ld\n", br_timer_value(&p->message_age_timer));
+	return sysfs_emit(buf, "%ld\n", br_timer_value(&p->message_age_timer));
 }
 static BRPORT_ATTR(message_age_timer, 0444, show_message_age_timer, NULL);
 
 static ssize_t show_forward_delay_timer(struct net_bridge_port *p,
 					    char *buf)
 {
-	return sprintf(buf, "%ld\n", br_timer_value(&p->forward_delay_timer));
+	return sysfs_emit(buf, "%ld\n", br_timer_value(&p->forward_delay_timer));
 }
 static BRPORT_ATTR(forward_delay_timer, 0444, show_forward_delay_timer, NULL);
 
 static ssize_t show_hold_timer(struct net_bridge_port *p,
 					    char *buf)
 {
-	return sprintf(buf, "%ld\n", br_timer_value(&p->hold_timer));
+	return sysfs_emit(buf, "%ld\n", br_timer_value(&p->hold_timer));
 }
 static BRPORT_ATTR(hold_timer, 0444, show_hold_timer, NULL);
 
@@ -182,7 +182,7 @@ static BRPORT_ATTR(flush, 0200, NULL, store_flush);
 
 static ssize_t show_group_fwd_mask(struct net_bridge_port *p, char *buf)
 {
-	return sprintf(buf, "%#x\n", p->group_fwd_mask);
+	return sysfs_emit(buf, "%#x\n", p->group_fwd_mask);
 }
 
 static int store_group_fwd_mask(struct net_bridge_port *p,
@@ -205,7 +205,7 @@ static ssize_t show_backup_port(struct net_bridge_port *p, char *buf)
 	rcu_read_lock();
 	backup_p = rcu_dereference(p->backup_port);
 	if (backup_p)
-		ret = sprintf(buf, "%s\n", backup_p->dev->name);
+		ret = sysfs_emit(buf, "%s\n", backup_p->dev->name);
 	rcu_read_unlock();
 
 	return ret;
@@ -244,7 +244,7 @@ BRPORT_ATTR_FLAG(isolated, BR_ISOLATED);
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
 {
-	return sprintf(buf, "%d\n", p->multicast_ctx.multicast_router);
+	return sysfs_emit(buf, "%d\n", p->multicast_ctx.multicast_router);
 }
 
 static int store_multicast_router(struct net_bridge_port *p,
-- 
2.43.0
Re: [PATCH net-next] net: bridge: use sysfs_emit instead of sprintf
Posted by Ido Schimmel 5 days, 14 hours ago 
On Sat, Jan 31, 2026 at 04:53:09PM +0000, David Corvaglia wrote:
> Replace sprintf with sysfs_emit in sysfs show() methods as outlined in
> Documentation/filesystems/sysfs.rst. sysfs_emit is preferred to sprintf 
> in sysfs show() methods as it is safer with buffer handling.
> 
> Signed-off-by: David Corvaglia <david@corvaglia.dev>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>

But the patch is introducing a few alignment issues and it would be good
to fix them in v2. See below.

[...]

> @@ -87,7 +87,7 @@ static DEVICE_ATTR_RW(forward_delay);
>  static ssize_t hello_time_show(struct device *d, struct device_attribute *attr,
>  			       char *buf)
>  {
> -	return sprintf(buf, "%lu\n",
> +	return sysfs_emit(buf, "%lu\n",
>  		       jiffies_to_clock_t(to_bridge(d)->hello_time));

Here

>  }
>  
> @@ -108,7 +108,7 @@ static DEVICE_ATTR_RW(hello_time);
>  static ssize_t max_age_show(struct device *d, struct device_attribute *attr,
>  			    char *buf)
>  {
> -	return sprintf(buf, "%lu\n",
> +	return sysfs_emit(buf, "%lu\n",
>  		       jiffies_to_clock_t(to_bridge(d)->max_age));

Here

>  }
>  

[...]

>  static int set_group_fwd_mask(struct net_bridge *br, unsigned long val,
> @@ -200,7 +200,7 @@ static ssize_t priority_show(struct device *d, struct device_attribute *attr,
>  			     char *buf)
>  {
>  	struct net_bridge *br = to_bridge(d);
> -	return sprintf(buf, "%d\n",
> +	return sysfs_emit(buf, "%d\n",
>  		       (br->bridge_id.prio[0] << 8) | br->bridge_id.prio[1]);

Here

>  }

[...]

> @@ -425,7 +425,7 @@ static ssize_t multicast_query_use_ifaddr_show(struct device *d,
>  					       char *buf)
>  {
>  	struct net_bridge *br = to_bridge(d);
> -	return sprintf(buf, "%d\n",
> +	return sysfs_emit(buf, "%d\n",
>  		       br_opt_get(br, BROPT_MULTICAST_QUERY_USE_IFADDR));

Here

>  }

> @@ -583,7 +583,7 @@ static ssize_t multicast_last_member_interval_show(
>  	struct device *d, struct device_attribute *attr, char *buf)
>  {
>  	struct net_bridge *br = to_bridge(d);
> -	return sprintf(buf, "%lu\n",
> +	return sysfs_emit(buf, "%lu\n",
>  		       jiffies_to_clock_t(br->multicast_ctx.multicast_last_member_interval));

Here

>  }
>  
> @@ -606,7 +606,7 @@ static ssize_t multicast_membership_interval_show(
>  	struct device *d, struct device_attribute *attr, char *buf)
>  {
>  	struct net_bridge *br = to_bridge(d);
> -	return sprintf(buf, "%lu\n",
> +	return sysfs_emit(buf, "%lu\n",
>  		       jiffies_to_clock_t(br->multicast_ctx.multicast_membership_interval));

Here

>  }
>  
> @@ -630,7 +630,7 @@ static ssize_t multicast_querier_interval_show(struct device *d,
>  					       char *buf)
>  {
>  	struct net_bridge *br = to_bridge(d);
> -	return sprintf(buf, "%lu\n",
> +	return sysfs_emit(buf, "%lu\n",
>  		       jiffies_to_clock_t(br->multicast_ctx.multicast_querier_interval));

Here

>  }
>  
> @@ -654,7 +654,7 @@ static ssize_t multicast_query_interval_show(struct device *d,
>  					     char *buf)
>  {
>  	struct net_bridge *br = to_bridge(d);
> -	return sprintf(buf, "%lu\n",
> +	return sysfs_emit(buf, "%lu\n",
>  		       jiffies_to_clock_t(br->multicast_ctx.multicast_query_interval));

Here

>  }

[...]

> @@ -727,7 +727,7 @@ static ssize_t multicast_stats_enabled_show(struct device *d,
>  {
>  	struct net_bridge *br = to_bridge(d);
>  
> -	return sprintf(buf, "%d\n",
> +	return sysfs_emit(buf, "%d\n",
>  		       br_opt_get(br, BROPT_MULTICAST_STATS_ENABLED));

Here

>  }
Re: [PATCH net-next] net: bridge: use sysfs_emit instead of sprintf
Posted by Nikolay Aleksandrov 5 days, 21 hours ago 
On 31/01/2026 18:53, David Corvaglia wrote:
> Replace sprintf with sysfs_emit in sysfs show() methods as outlined in
> Documentation/filesystems/sysfs.rst. sysfs_emit is preferred to sprintf
> in sysfs show() methods as it is safer with buffer handling.
> 
> Signed-off-by: David Corvaglia <david@corvaglia.dev>
> ---
> This is my first patch to the kernel! I've been able to build and boot
> with the patch. I also tested the sysfs reads and they seem to be
> correct. Any feedback is appreciated.
> 
>   net/bridge/br_stp_if.c   |  2 +-
>   net/bridge/br_sysfs_br.c | 84 ++++++++++++++++++++--------------------
>   net/bridge/br_sysfs_if.c | 32 +++++++--------
>   3 files changed, 59 insertions(+), 59 deletions(-)
> 

Hi,
IIUC it is safer because it takes into account the provided buffer's size (PAGE_SIZE).
I'm saying it for the curious as  I only found in Documentation/filesystems/sysfs.rst:
"- New implementations of show() methods should only use sysfs_emit() or
   sysfs_emit_at() when formatting the value to be returned to user space."

Which does say "new implementations", also most of these are numbers
and cannot really fill the provided buffer, there is one instance of a string
but it is an interface name, so that is limited as well.

That being said, I'm ok with switching to sysfs_emit() and the patch looks good
to me so:

Acked-by: Nikolay Aleksandrov <razor@blackwall.org>

Thanks,
  Nik

Patchew 2.1-devel-b67e4c2

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