bpf: add schedule points to map alloc/free

edumazet · Alexei Starovoitov · commit 9147efcbe0b7 · 2017-12-12T15:27:22.000-08:00
While using large percpu maps, htab_map_alloc() can hold
cpu for hundreds of ms.

This patch adds cond_resched() calls to percpu alloc/free
call sites, all running in process context.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
@@ -114,6 +114,7 @@ static void htab_free_elems(struct bpf_htab *htab)
 		pptr = htab_elem_get_ptr(get_htab_elem(htab, i),
 					 htab->map.key_size);
 		free_percpu(pptr);
+		cond_resched();
 	}
 free_elems:
 	bpf_map_area_free(htab->elems);
@@ -159,6 +160,7 @@ static int prealloc_init(struct bpf_htab *htab)
 			goto free_elems;
 		htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size,
 				  pptr);
+		cond_resched();
 	}
 
 skip_percpu_elems:

Original file line number	Diff line number	Diff line change
`@@ -114,6 +114,7 @@ static void htab_free_elems(struct bpf_htab *htab)`
`114`	`114`	`pptr = htab_elem_get_ptr(get_htab_elem(htab, i),`
`115`	`115`	`htab->map.key_size);`
`116`	`116`	`free_percpu(pptr);`
	`117`	`+ cond_resched();`
`117`	`118`	`}`
`118`	`119`	`free_elems:`
`119`	`120`	`bpf_map_area_free(htab->elems);`
`@@ -159,6 +160,7 @@ static int prealloc_init(struct bpf_htab *htab)`
`159`	`160`	`goto free_elems;`
`160`	`161`	`htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size,`
`161`	`162`	`pptr);`
	`163`	`+ cond_resched();`
`162`	`164`	`}`
`163`	`165`
`164`	`166`	`skip_percpu_elems:`