sysctl: define proc_do_static_key()

Convert proc_dointvec_minmax_bpf_stats() into a more generic
helper, since we are going to use jump labels more often.

Note that sysctl_bpf_stats_enabled is removed, since
it is no longer needed/used.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 26 insertions, 23 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 5df8e9e2a393..b92ef9f73e42 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -600,7 +600,6 @@ void bpf_map_area_free(void *base);
 void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr);
 
 extern int sysctl_unprivileged_bpf_disabled;
-extern int sysctl_bpf_stats_enabled;
 
 int bpf_map_new_fd(struct bpf_map *map, int flags);
 int bpf_prog_new_fd(struct bpf_prog *prog);
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index b769ecfcc3bd..aadd310769d0 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -63,6 +63,9 @@ extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
                                       void __user *, size_t *, loff_t *);
 extern int proc_do_large_bitmap(struct ctl_table *, int,
                                 void __user *, size_t *, loff_t *);
+extern int proc_do_static_key(struct ctl_table *table, int write,
+                              void __user *buffer, size_t *lenp,
+                              loff_t *ppos);
 
 /*
  * Register a set of sysctl names by calling register_sysctl_table
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 7c473f208a10..080e2bb644cc 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2097,7 +2097,6 @@ int __weak skb_copy_bits(const struct sk_buff *skb, int offset, void *to,
 
 DEFINE_STATIC_KEY_FALSE(bpf_stats_enabled_key);
 EXPORT_SYMBOL(bpf_stats_enabled_key);
-int sysctl_bpf_stats_enabled __read_mostly;
 
 /* All definitions of tracepoints related to BPF. */
 #define CREATE_TRACE_POINTS
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 7d1008be6173..1beca96fb625 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -230,11 +230,6 @@ static int proc_dostring_coredump(struct ctl_table *table, int write,
 #endif
 static int proc_dopipe_max_size(struct ctl_table *table, int write,
                 void __user *buffer, size_t *lenp, loff_t *ppos);
-#ifdef CONFIG_BPF_SYSCALL
-static int proc_dointvec_minmax_bpf_stats(struct ctl_table *table, int write,
-                                          void __user *buffer, size_t *lenp,
-                                          loff_t *ppos);
-#endif
 
 #ifdef CONFIG_MAGIC_SYSRQ
 /* Note: sysrq code uses its own private copy */
@@ -1253,12 +1248,10 @@ static struct ctl_table kern_table[] = {
         },
         {
                 .procname       = "bpf_stats_enabled",
-                .data           = &sysctl_bpf_stats_enabled,
-                .maxlen         = sizeof(sysctl_bpf_stats_enabled),
+                .data           = &bpf_stats_enabled_key.key,
+                .maxlen         = sizeof(bpf_stats_enabled_key),
                 .mode           = 0644,
-                .proc_handler   = proc_dointvec_minmax_bpf_stats,
-                .extra1         = &zero,
-                .extra2         = &one,
+                .proc_handler   = proc_do_static_key,
         },
 #endif
 #if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU)
@@ -3374,26 +3367,35 @@ int proc_do_large_bitmap(struct ctl_table *table, int write,
 
 #endif /* CONFIG_PROC_SYSCTL */
 
-#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_SYSCTL)
-static int proc_dointvec_minmax_bpf_stats(struct ctl_table *table, int write,
-                                          void __user *buffer, size_t *lenp,
-                                          loff_t *ppos)
+#if defined(CONFIG_SYSCTL)
+int proc_do_static_key(struct ctl_table *table, int write,
+                       void __user *buffer, size_t *lenp,
+                       loff_t *ppos)
 {
-        int ret, bpf_stats = *(int *)table->data;
-        struct ctl_table tmp = *table;
+        struct static_key *key = (struct static_key *)table->data;
+        static DEFINE_MUTEX(static_key_mutex);
+        int val, ret;
+        struct ctl_table tmp = {
+                .data   = &val,
+                .maxlen = sizeof(val),
+                .mode   = table->mode,
+                .extra1 = &zero,
+                .extra2 = &one,
+        };
 
         if (write && !capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
-        tmp.data = &bpf_stats;
+        mutex_lock(&static_key_mutex);
+        val = static_key_enabled(key);
         ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
         if (write && !ret) {
-                *(int *)table->data = bpf_stats;
-                if (bpf_stats)
-                        static_branch_enable(&bpf_stats_enabled_key);
+                if (val)
+                        static_key_enable(key);
                 else
-                        static_branch_disable(&bpf_stats_enabled_key);
+                        static_key_disable(key);
         }
+        mutex_unlock(&static_key_mutex);
         return ret;
 }
 #endif