bpf: Use u64_stats_t in struct bpf_prog_stats

Commit 316580b69d0a ("u64_stats: provide u64_stats_t type")
fixed possible load/store tearing on 64bit arches.

For instance the following C code

stats->nsecs += sched_clock() - start;

Could be rightfully implemented like this by a compiler,
confusing concurrent readers a lot:

stats->nsecs += sched_clock();
// arbitrary delay
stats->nsecs -= start;

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211026214133.3114279-4-eric.dumazet@gmail.com

1 files changed, 5 insertions, 5 deletions

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 2fffe9cc50f9..9782e3245852 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -553,9 +553,9 @@ struct bpf_binary_header {
 };
 
 struct bpf_prog_stats {
-	u64 cnt;
-	u64 nsecs;
-	u64 misses;
+	u64_stats_t cnt;
+	u64_stats_t nsecs;
+	u64_stats_t misses;
 	struct u64_stats_sync syncp;
 } __aligned(2 * sizeof(u64));
 
@@ -617,8 +617,8 @@ static __always_inline u32 __bpf_prog_run(const struct bpf_prog *prog,
 		ret = dfunc(ctx, prog->insnsi, prog->bpf_func);
 		stats = this_cpu_ptr(prog->stats);
 		flags = u64_stats_update_begin_irqsave(&stats->syncp);
-		stats->cnt++;
-		stats->nsecs += sched_clock() - start;
+		u64_stats_inc(&stats->cnt);
+		u64_stats_add(&stats->nsecs, sched_clock() - start);
 		u64_stats_update_end_irqrestore(&stats->syncp, flags);
 	} else {
 		ret = dfunc(ctx, prog->insnsi, prog->bpf_func);