bpf: devmap, use cond_resched instead of cpu_relax

jrfastab · davem330 · commit 374fb014fc5b · 2017-09-08T21:11:00.000-07:00
Be a bit more friendly about waiting for flush bits to complete.
Replace the cpu_relax() with a cond_resched().

Suggested-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Acked-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Signed-off-by: John Fastabend &lt;john.fastabend@gmail.com&gt;
Acked-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
@@ -159,7 +159,7 @@ static void dev_map_free(struct bpf_map *map)
 		unsigned long *bitmap = per_cpu_ptr(dtab->flush_needed, cpu);
 
 		while (!bitmap_empty(bitmap, dtab->map.max_entries))
-			cpu_relax();
+			cond_resched();
 	}
 
 	for (i = 0; i < dtab->map.max_entries; i++) {

Original file line number	Diff line number	Diff line change
`@@ -159,7 +159,7 @@ static void dev_map_free(struct bpf_map *map)`
`159`	`159`	`unsigned long *bitmap = per_cpu_ptr(dtab->flush_needed, cpu);`
`160`	`160`
`161`	`161`	`while (!bitmap_empty(bitmap, dtab->map.max_entries))`
`162`		`- cpu_relax();`
	`162`	`+ cond_resched();`
`163`	`163`	`}`
`164`	`164`
`165`	`165`	`for (i = 0; i < dtab->map.max_entries; i++) {`