Hi David,
here is a small cleanup pull request of batman-adv to go into net-next.
Please pull or let me know of any problem!
Thank you, Simon
The following changes since commit bb6d3fb354c5ee8d6bde2d576eb7220ea09862b9:
Linux 5.6-rc1 (2020-02-09 16:08:48 -0800)
are available in the Git repository at:
git://git.open-mesh.org/linux-merge.git tags/batadv-next-for-davem-20200306
for you to fetch changes up to 5f27eb055d5c5814785fb9cf0ae4a4c150a8f334:
batman-adv: Replace zero-length array with flexible-array member (2020-02-17 22:43:42 +0100)
---------------------------------------------------------------- This cleanup patchset includes the following patches:
- bump version strings, by Simon Wunderlich
- Avoid RCU list-traversal in spinlock, by Sven Eckelmann
- Replace zero-length array with flexible-array member, by Gustavo A. R. Silva
---------------------------------------------------------------- Gustavo A. R. Silva (1): batman-adv: Replace zero-length array with flexible-array member
Simon Wunderlich (1): batman-adv: Start new development cycle
Sven Eckelmann (1): batman-adv: Avoid RCU list-traversal in spinlock
net/batman-adv/distributed-arp-table.c | 2 +- net/batman-adv/main.h | 2 +- net/batman-adv/translation-table.c | 8 ++++---- 3 files changed, 6 insertions(+), 6 deletions(-)
Signed-off-by: Simon Wunderlich sw@simonwunderlich.de --- net/batman-adv/main.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/batman-adv/main.h b/net/batman-adv/main.h index 692306df7b6f..2a234d0ad445 100644 --- a/net/batman-adv/main.h +++ b/net/batman-adv/main.h @@ -13,7 +13,7 @@ #define BATADV_DRIVER_DEVICE "batman-adv"
#ifndef BATADV_SOURCE_VERSION -#define BATADV_SOURCE_VERSION "2020.0" +#define BATADV_SOURCE_VERSION "2020.1" #endif
/* B.A.T.M.A.N. parameters */
From: Sven Eckelmann sven@narfation.org
The new CONFIG_PROVE_RCU_LIST requires a condition statement in (h)list_for_each_entry_rcu when the code might be executed in a non RCU non-reader section with the writer lock. Otherwise lockdep might cause a false positive warning like
============================= WARNING: suspicious RCU usage ----------------------------- translation-table.c:940 RCU-list traversed in non-reader section!!
batman-adv is (mostly) following the examples from the RCU documentation and is using the normal list-traversal primitives instead of the RCU list-traversal primitives when the writer (spin)lock is held.
The remaining users of RCU list-traversal primitives with writer spinlock have to be converted to the same style as the rest of the code.
Reported-by: Madhuparna Bhowmik madhuparnabhowmik10@gmail.com Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Simon Wunderlich sw@simonwunderlich.de --- net/batman-adv/translation-table.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c index 852932838ddc..a9635c882fe0 100644 --- a/net/batman-adv/translation-table.c +++ b/net/batman-adv/translation-table.c @@ -862,7 +862,7 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node, u8 *tt_change_ptr;
spin_lock_bh(&orig_node->vlan_list_lock); - hlist_for_each_entry_rcu(vlan, &orig_node->vlan_list, list) { + hlist_for_each_entry(vlan, &orig_node->vlan_list, list) { num_vlan++; num_entries += atomic_read(&vlan->tt.num_entries); } @@ -888,7 +888,7 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node, (*tt_data)->num_vlan = htons(num_vlan);
tt_vlan = (struct batadv_tvlv_tt_vlan_data *)(*tt_data + 1); - hlist_for_each_entry_rcu(vlan, &orig_node->vlan_list, list) { + hlist_for_each_entry(vlan, &orig_node->vlan_list, list) { tt_vlan->vid = htons(vlan->vid); tt_vlan->crc = htonl(vlan->tt.crc);
@@ -937,7 +937,7 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv, int change_offset;
spin_lock_bh(&bat_priv->softif_vlan_list_lock); - hlist_for_each_entry_rcu(vlan, &bat_priv->softif_vlan_list, list) { + hlist_for_each_entry(vlan, &bat_priv->softif_vlan_list, list) { vlan_entries = atomic_read(&vlan->tt.num_entries); if (vlan_entries < 1) continue; @@ -967,7 +967,7 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv, (*tt_data)->num_vlan = htons(num_vlan);
tt_vlan = (struct batadv_tvlv_tt_vlan_data *)(*tt_data + 1); - hlist_for_each_entry_rcu(vlan, &bat_priv->softif_vlan_list, list) { + hlist_for_each_entry(vlan, &bat_priv->softif_vlan_list, list) { vlan_entries = atomic_read(&vlan->tt.num_entries); if (vlan_entries < 1) continue;
From: "Gustavo A. R. Silva" gustavo@embeddedor.com
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99:
struct foo { int stuff; struct boo array[]; };
By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by this change:
"Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva gustavo@embeddedor.com Signed-off-by: Sven Eckelman sven@narfation.org Signed-off-by: Simon Wunderlich sw@simonwunderlich.de --- net/batman-adv/distributed-arp-table.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c index 3d21dd83f8cc..b85da4b7a77b 100644 --- a/net/batman-adv/distributed-arp-table.c +++ b/net/batman-adv/distributed-arp-table.c @@ -88,7 +88,7 @@ struct batadv_dhcp_packet { __u8 sname[64]; __u8 file[128]; __be32 magic; - __u8 options[0]; + __u8 options[]; };
#define BATADV_DHCP_YIADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->yiaddr)
b.a.t.m.a.n@lists.open-mesh.org
-
Simon Wunderlich