[ovs-dev] datapath: Provide this_cpu_{read, inc, dec} wrappers for v2.6.33
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Message ID 1443581482-18862-1-git-send-email-simon.horman@netronome.com
State Not Applicable
Headers show

Commit Message

Simon Horman Sept. 30, 2015, 2:51 a.m. UTC
My understanding is that prior to linux kernel commit
dd17c8f72993 ("percpu: remove per_cpu__ prefix.") per_cpu_var(),
which was included in v2.6.34, was used to wrap per cpu variables

In order to allow Open vSwitch to compile against  v2.6.33
and earlier use per_cpu_var() and in order to allow compilation
with latter kernels provide a per_cpu_var() which performs
an identity map.

In the case of v2.6.32 the kernel does not supply this_cpu_{read,inc,dec}
and the compat code for RHEL6 in datapath/linux/compat/include/linux/percpu.h
is used.

Fixes: 60759b2b9d0c ("datapath: Remove recirc stack depth limit check")
Signed-off-by: Simon Horman <simon.horman@netronome.com>

---

* I was searching for an approach that would not involve
  updating actions.c but I was not able to find one.
* This problem has been present since around August 2014,
  perhaps an easier approach would be to simply drop support for
  v2.6.32 and v2.6.33 Kernels.
* This problem appears to be present in both master ranch-v2.4

Compile tested against: 4.2.2, 4.1.9, 4.0.9, 3.19.8, 3.18.21, 3.17.8, 3.16.7,
3.15.10, 3.14.53, 3.13.11, 3.12.48, 3.11.10, 3.10.89, 3.9.11, 3.8.13, 3.7.10,
3.6.11, 3.5.7, 3.4.109, 3.3.8, 3.2.71, 3.1.10, 3.0.101, 2.6.39.4, 2.6.38.8.

Compile tested in conjunction with "datapath: compat: provide
skb_checksum_start_offset for 2.6.37 and earlier" on: 2.6.37.6, 2.6.36.4,
2.6.35.14, 2.6.34.15, 2.6.33.20, 2.6.32.68.
---
 datapath/actions.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

Patch
diff mbox

diff --git a/datapath/actions.c b/datapath/actions.c
index c529bbb9b6ee..e8ca114beec2 100644
--- a/datapath/actions.c
+++ b/datapath/actions.c
@@ -982,12 +982,22 @@  static void process_deferred_actions(struct datapath *dp)
 	action_fifo_init(fifo);
 }
 
+#if LINUX_VERSION_CODE == KERNEL_VERSION(2,6,33)
+#define ovs_this_cpu_read(ptr) this_cpu_read(per_cpu_var(ptr))
+#define ovs_this_cpu_inc(ptr) this_cpu_inc(per_cpu_var(ptr))
+#define ovs_this_cpu_dec(ptr) this_cpu_dec(per_cpu_var(ptr))
+#else
+#define ovs_this_cpu_read(ptr) this_cpu_read(ptr)
+#define ovs_this_cpu_inc(ptr) this_cpu_inc(ptr)
+#define ovs_this_cpu_dec(ptr) this_cpu_dec(ptr)
+#endif
+
 /* Execute a list of actions against 'skb'. */
 int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb,
 			const struct sw_flow_actions *acts,
 			struct sw_flow_key *key)
 {
-	int level = this_cpu_read(exec_actions_level);
+	int level = ovs_this_cpu_read(exec_actions_level);
 	int err;
 
 	if (unlikely(level >= EXEC_ACTIONS_LEVEL_LIMIT)) {
@@ -999,14 +1009,14 @@  int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb,
 		return -ELOOP;
 	}
 
-	this_cpu_inc(exec_actions_level);
+	ovs_this_cpu_inc(exec_actions_level);
 	err = do_execute_actions(dp, skb, key,
 				 acts->actions, acts->actions_len);
 
 	if (!level)
 		process_deferred_actions(dp);
 
-	this_cpu_dec(exec_actions_level);
+	ovs_this_cpu_dec(exec_actions_level);
 
 	/* This return status currently does not reflect the errors
 	 * encounted during deferred actions execution. Probably needs to