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Subject[RFC patch 13/19] bpf: Use migrate_disable/enable in array macros and cgroup/lirc code.
From: David Miller <davem@davemloft.net>

Replace the preemption disable/enable with migrate_disable/enable() to
reflect the actual requirement and to allow PREEMPT_RT to substitute it
with an actual migration disable mechanism which does not disable
preemption.

Including the code paths that go via __bpf_prog_run_save_cb().

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
include/linux/bpf.h | 8 ++++----
include/linux/filter.h | 5 +++--
2 files changed, 7 insertions(+), 6 deletions(-)

--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -885,7 +885,7 @@ int bpf_prog_array_copy(struct bpf_prog_
struct bpf_prog *_prog; \
struct bpf_prog_array *_array; \
u32 _ret = 1; \
- preempt_disable(); \
+ migrate_disable(); \
rcu_read_lock(); \
_array = rcu_dereference(array); \
if (unlikely(check_non_null && !_array))\
@@ -898,7 +898,7 @@ int bpf_prog_array_copy(struct bpf_prog_
} \
_out: \
rcu_read_unlock(); \
- preempt_enable(); \
+ migrate_enable(); \
_ret; \
})

@@ -932,7 +932,7 @@ int bpf_prog_array_copy(struct bpf_prog_
u32 ret; \
u32 _ret = 1; \
u32 _cn = 0; \
- preempt_disable(); \
+ migrate_disable(); \
rcu_read_lock(); \
_array = rcu_dereference(array); \
_item = &_array->items[0]; \
@@ -944,7 +944,7 @@ int bpf_prog_array_copy(struct bpf_prog_
_item++; \
} \
rcu_read_unlock(); \
- preempt_enable(); \
+ migrate_enable(); \
if (_ret) \
_ret = (_cn ? NET_XMIT_CN : NET_XMIT_SUCCESS); \
else \
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -673,6 +673,7 @@ static inline u8 *bpf_skb_cb(struct sk_b
return qdisc_skb_cb(skb)->data;
}

+/* Must be invoked with migration disabled */
static inline u32 __bpf_prog_run_save_cb(const struct bpf_prog *prog,
struct sk_buff *skb)
{
@@ -698,9 +699,9 @@ static inline u32 bpf_prog_run_save_cb(c
{
u32 res;

- preempt_disable();
+ migrate_disable();
res = __bpf_prog_run_save_cb(prog, skb);
- preempt_enable();
+ migrate_enable();
return res;
}

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