| Message ID | 20221121174605.2456845-8-bigeasy@linutronix.de (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v2,net,1/7] Revert "net: hsr: use hlist_head instead of list_head for mac addresses" | expand |
On Mon Nov 21 2022, Sebastian Andrzej Siewior wrote: > self_node_db is a list_head with one entry of struct hsr_node. The > purpose is to hold the two MAC addresses of the node itself. > It is convenient to recycle the structure. However having a list_head > and fetching always the first entry is not really optimal. > > Created a new data strucure contaning the two MAC addresses named > hsr_self_node. Access that structured like an RCU protected pointer so ^ structure > it can be replaced on the fly withou blocking the reader. ^ without > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Lacks a Fixes tag. Looks rather like an optimization than a bugfix? So, maybe this one should go to net-next instead. [snip] > +struct hsr_self_node { > + unsigned char macaddress_A[6]; ^ ETH_ALEN > + unsigned char macaddress_B[6]; ^ ETH_ALEN > + struct rcu_head rcu_head; > +}; > + Thanks, Kurt
On 2022-11-22 10:20:49 [+0100], Kurt Kanzenbach wrote: > On Mon Nov 21 2022, Sebastian Andrzej Siewior wrote: > > self_node_db is a list_head with one entry of struct hsr_node. The > > purpose is to hold the two MAC addresses of the node itself. > > It is convenient to recycle the structure. However having a list_head > > and fetching always the first entry is not really optimal. > > > > Created a new data strucure contaning the two MAC addresses named > > hsr_self_node. Access that structured like an RCU protected pointer so > ^ structure > > > it can be replaced on the fly withou blocking the reader. > ^ without argh. > > > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > > Lacks a Fixes tag. Looks rather like an optimization than a bugfix? So, > maybe this one should go to net-next instead. The initial motivation for hsr: Avoid double remove of a node was to use hlist_del_init_rcu() for the remove and then use hlist_unhashed() for the check. This got me to this because I was not sure why we have this list for a single node which isn't needed and looks like waste of memory and confusion (a list for a single entry?). In the end I decided midway to stay with the list_head and just add a `removed' field to deal with this. Can we ignore this patch and then I repost just that one for next? > [snip] > > > +struct hsr_self_node { > > + unsigned char macaddress_A[6]; > ^ ETH_ALEN > > > + unsigned char macaddress_B[6]; > ^ ETH_ALEN > > + struct rcu_head rcu_head; > > +}; > > + Sure. > Thanks, > Kurt Sebastian
Hi Sebastian,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on net/master]
url: https://github.com/intel-lab-lkp/linux/commits/Sebastian-Andrzej-Siewior/Revert-net-hsr-use-hlist_head-instead-of-list_head-for-mac-addresses/20221122-024634
patch link: https://lore.kernel.org/r/20221121174605.2456845-8-bigeasy%40linutronix.de
patch subject: [PATCH v2 net 7/7] hsr: Use a single struct for self_node.
config: ia64-randconfig-s033-20221124
compiler: ia64-linux-gcc (GCC) 12.1.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# apt-get install sparse
# sparse version: v0.6.4-39-gce1a6720-dirty
# https://github.com/intel-lab-lkp/linux/commit/80e94f7b5ffe417abb25777833f59121dae6b17f
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Sebastian-Andrzej-Siewior/Revert-net-hsr-use-hlist_head-instead-of-list_head-for-mac-addresses/20221122-024634
git checkout 80e94f7b5ffe417abb25777833f59121dae6b17f
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=ia64 SHELL=/bin/bash drivers/hid/ net/hsr/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
sparse warnings: (new ones prefixed by >>)
>> net/hsr/hsr_framereg.c:45:14: sparse: sparse: incompatible types in comparison expression (different address spaces):
>> net/hsr/hsr_framereg.c:45:14: sparse: struct hsr_self_node [noderef] __rcu *
>> net/hsr/hsr_framereg.c:45:14: sparse: struct hsr_self_node *
net/hsr/hsr_framereg.c:91:15: sparse: sparse: incompatible types in comparison expression (different address spaces):
net/hsr/hsr_framereg.c:91:15: sparse: struct hsr_self_node [noderef] __rcu *
net/hsr/hsr_framereg.c:91:15: sparse: struct hsr_self_node *
net/hsr/hsr_framereg.c:91:15: sparse: sparse: incompatible types in comparison expression (different address spaces):
net/hsr/hsr_framereg.c:91:15: sparse: struct hsr_self_node [noderef] __rcu *
net/hsr/hsr_framereg.c:91:15: sparse: struct hsr_self_node *
net/hsr/hsr_framereg.c:105:15: sparse: sparse: incompatible types in comparison expression (different address spaces):
net/hsr/hsr_framereg.c:105:15: sparse: struct hsr_self_node [noderef] __rcu *
net/hsr/hsr_framereg.c:105:15: sparse: struct hsr_self_node *
net/hsr/hsr_framereg.c:105:15: sparse: sparse: incompatible types in comparison expression (different address spaces):
net/hsr/hsr_framereg.c:105:15: sparse: struct hsr_self_node [noderef] __rcu *
net/hsr/hsr_framereg.c:105:15: sparse: struct hsr_self_node *
vim +45 net/hsr/hsr_framereg.c
38
39 bool hsr_addr_is_self(struct hsr_priv *hsr, unsigned char *addr)
40 {
41 struct hsr_self_node *sn;
42 bool ret = false;
43
44 rcu_read_lock();
> 45 sn = rcu_dereference(hsr->self_node);
46 if (!sn) {
47 WARN_ONCE(1, "HSR: No self node\n");
48 goto out;
49 }
50
51 if (ether_addr_equal(addr, sn->macaddress_A) ||
52 ether_addr_equal(addr, sn->macaddress_B))
53 ret = true;
54 out:
55 rcu_read_unlock();
56 return ret;
57 }
58
diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c index b1e86a7265b32..5a236aae2366f 100644 --- a/net/hsr/hsr_device.c +++ b/net/hsr/hsr_device.c @@ -490,7 +490,6 @@ int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2], hsr = netdev_priv(hsr_dev); INIT_LIST_HEAD(&hsr->ports); INIT_LIST_HEAD(&hsr->node_db); - INIT_LIST_HEAD(&hsr->self_node_db); spin_lock_init(&hsr->list_lock); eth_hw_addr_set(hsr_dev, slave[0]->dev_addr); diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c index 39a6088080e93..00db74d96583d 100644 --- a/net/hsr/hsr_framereg.c +++ b/net/hsr/hsr_framereg.c @@ -38,21 +38,22 @@ static bool seq_nr_after(u16 a, u16 b) bool hsr_addr_is_self(struct hsr_priv *hsr, unsigned char *addr) { - struct hsr_node *node; + struct hsr_self_node *sn; + bool ret = false; - node = list_first_or_null_rcu(&hsr->self_node_db, struct hsr_node, - mac_list); - if (!node) { + rcu_read_lock(); + sn = rcu_dereference(hsr->self_node); + if (!sn) { WARN_ONCE(1, "HSR: No self node\n"); - return false; + goto out; } - if (ether_addr_equal(addr, node->macaddress_A)) - return true; - if (ether_addr_equal(addr, node->macaddress_B)) - return true; - - return false; + if (ether_addr_equal(addr, sn->macaddress_A) || + ether_addr_equal(addr, sn->macaddress_B)) + ret = true; +out: + rcu_read_unlock(); + return ret; } /* Search for mac entry. Caller must hold rcu read lock. @@ -70,50 +71,42 @@ static struct hsr_node *find_node_by_addr_A(struct list_head *node_db, return NULL; } -/* Helper for device init; the self_node_db is used in hsr_rcv() to recognize +/* Helper for device init; the self_node is used in hsr_rcv() to recognize * frames from self that's been looped over the HSR ring. */ int hsr_create_self_node(struct hsr_priv *hsr, const unsigned char addr_a[ETH_ALEN], const unsigned char addr_b[ETH_ALEN]) { - struct list_head *self_node_db = &hsr->self_node_db; - struct hsr_node *node, *oldnode; + struct hsr_self_node *sn, *old; - node = kmalloc(sizeof(*node), GFP_KERNEL); - if (!node) + sn = kmalloc(sizeof(*sn), GFP_KERNEL); + if (!sn) return -ENOMEM; - ether_addr_copy(node->macaddress_A, addr_a); - ether_addr_copy(node->macaddress_B, addr_b); + ether_addr_copy(sn->macaddress_A, addr_a); + ether_addr_copy(sn->macaddress_B, addr_b); spin_lock_bh(&hsr->list_lock); - oldnode = list_first_or_null_rcu(self_node_db, - struct hsr_node, mac_list); - if (oldnode) { - list_replace_rcu(&oldnode->mac_list, &node->mac_list); - spin_unlock_bh(&hsr->list_lock); - kfree_rcu(oldnode, rcu_head); - } else { - list_add_tail_rcu(&node->mac_list, self_node_db); - spin_unlock_bh(&hsr->list_lock); - } + old = rcu_replace_pointer(hsr->self_node, sn, + lockdep_is_held(&hsr->list_lock)); + spin_unlock_bh(&hsr->list_lock); + if (old) + kfree_rcu(old, rcu_head); return 0; } void hsr_del_self_node(struct hsr_priv *hsr) { - struct list_head *self_node_db = &hsr->self_node_db; - struct hsr_node *node; + struct hsr_self_node *old; spin_lock_bh(&hsr->list_lock); - node = list_first_or_null_rcu(self_node_db, struct hsr_node, mac_list); - if (node) { - list_del_rcu(&node->mac_list); - kfree_rcu(node, rcu_head); - } + old = rcu_replace_pointer(hsr->self_node, NULL, + lockdep_is_held(&hsr->list_lock)); spin_unlock_bh(&hsr->list_lock); + if (old) + kfree_rcu(old, rcu_head); } void hsr_del_nodes(struct list_head *node_db) diff --git a/net/hsr/hsr_main.h b/net/hsr/hsr_main.h index 16ae9fb09ccd2..bbbff6b71e92f 100644 --- a/net/hsr/hsr_main.h +++ b/net/hsr/hsr_main.h @@ -182,11 +182,17 @@ struct hsr_proto_ops { void (*update_san_info)(struct hsr_node *node, bool is_sup); }; +struct hsr_self_node { + unsigned char macaddress_A[6]; + unsigned char macaddress_B[6]; + struct rcu_head rcu_head; +}; + struct hsr_priv { struct rcu_head rcu_head; struct list_head ports; struct list_head node_db; /* Known HSR nodes */ - struct list_head self_node_db; /* MACs of slaves */ + struct hsr_self_node *self_node; /* MACs of slaves */ struct timer_list announce_timer; /* Supervision frame dispatch */ struct timer_list prune_timer; int announce_count;
self_node_db is a list_head with one entry of struct hsr_node. The purpose is to hold the two MAC addresses of the node itself. It is convenient to recycle the structure. However having a list_head and fetching always the first entry is not really optimal. Created a new data strucure contaning the two MAC addresses named hsr_self_node. Access that structured like an RCU protected pointer so it can be replaced on the fly withou blocking the reader. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- net/hsr/hsr_device.c | 1 - net/hsr/hsr_framereg.c | 63 +++++++++++++++++++----------------------- net/hsr/hsr_main.h | 8 +++++- 3 files changed, 35 insertions(+), 37 deletions(-)