Re: [PATCH bluetooth-next 4/4] mac802154: use atomic ops for sequence incrementation

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Hello.

On 22/05/15 10:57, Alexander Aring wrote:
This patch will use atomic operations for sequence number incrementation
while MAC header generation. Upper layers like af_802154 or 6LoWPAN
could call this function in a parallel context while generating 802.15.4
MAC header before queuing into wpan interfaces transmit queue.

Signed-off-by: Alexander Aring <alex.aring@xxxxxxxxx>
---
  include/net/cfg802154.h |  4 ++--
  net/mac802154/iface.c   | 12 ++++++------
  2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/include/net/cfg802154.h b/include/net/cfg802154.h
index c6aa1d2..4de59aa 100644
--- a/include/net/cfg802154.h
+++ b/include/net/cfg802154.h
@@ -177,9 +177,9 @@ struct wpan_dev {
  	__le64 extended_addr;
/* MAC BSN field */
-	u8 bsn;
+	atomic_t bsn;
  	/* MAC DSN field */
-	u8 dsn;
+	atomic_t dsn;
u8 min_be;
  	u8 max_be;
diff --git a/net/mac802154/iface.c b/net/mac802154/iface.c
index 866d27f..f30788d 100644
--- a/net/mac802154/iface.c
+++ b/net/mac802154/iface.c
@@ -365,10 +365,7 @@ static int mac802154_header_create(struct sk_buff *skb,
  	hdr.fc.type = cb->type;
  	hdr.fc.security_enabled = cb->secen;
  	hdr.fc.ack_request = cb->ackreq;
-	/* TODO: use atomic_t as dsn, dsn need to be locked when AF_IEEE802154
-	 * and IEEE802154 6LoWPAN call this at the same time.
-	 */
-	hdr.seq = dev->ieee802154_ptr->dsn++;
+	hdr.seq = atomic_inc_return(&dev->ieee802154_ptr->dsn) & 0xFF;

After reviewing this in its full glory I also think the order needs to change an patch number 4 should come before 3.

if (mac802154_set_header_security(sdata, &hdr, cb) < 0)
  		return -EINVAL;
@@ -464,13 +461,16 @@ ieee802154_setup_sdata(struct ieee802154_sub_if_data *sdata,
  		       enum nl802154_iftype type)
  {
  	struct wpan_dev *wpan_dev = &sdata->wpan_dev;
+	u8 tmp;
/* set some type-dependent values */
  	sdata->vif.type = type;
  	sdata->wpan_dev.iftype = type;
- get_random_bytes(&wpan_dev->bsn, 1);
-	get_random_bytes(&wpan_dev->dsn, 1);
+	get_random_bytes(&tmp, sizeof(tmp));
+	atomic_set(&wpan_dev->bsn, tmp);
+	get_random_bytes(&tmp, sizeof(tmp));
+	atomic_set(&wpan_dev->dsn, tmp);
/* defaults per 802.15.4-2011 */
  	wpan_dev->min_be = 3;

After swapping you can add:

Reviewed-by: Stefan Schmidt <stefan@xxxxxxxxxxxxxxx>

This includes some smoke testing between two nodes (atusb and at86rf233), Basically ping6 with various sizes and a count of 1000 pings. No problem showed up with these patches during the testing.

regards
Stefan Schmidt
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