[v6,09/20] batman-adv: Convert batadv_dat_entry to kref
Commit Message
batman-adv uses a self-written reference implementation which is just based
on atomic_t. This is less obvious when reading the code than kref and
therefore increases the change that the reference counting will be missed.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
v6:
- removed patches which are now applied in the branch next
- rebased remaining patches on the patch
"batman-adv: Avoid recursive call_rcu for batadv_nc_node" which was
modified by Marek while he applied the patches (this unfortunately made
some of the remaining patches "hard" to apply)
v5:
- add hack which allows to compile against stable kernel like 3.2.44 which
also added the kref_get_unless_zero function
v4:
- fix function names in commit messages
- fix double whitespace in batadv_tt_orig_list_entry_release kerneldoc
- add extra patch for batadv_claim_free_ref kerneldoc fix
- change the phrase "free it" in all *_free_ref/*_put functions to "release it"
v3:
- update copyright year
v2:
- split patchset into fixes and kref migration to make it easier when the
decision is made where each patch will be applied
net/batman-adv/distributed-arp-table.c | 27 +++++++++++++++++++++------
net/batman-adv/types.h | 2 +-
2 files changed, 22 insertions(+), 7 deletions(-)
Comments
On Saturday, January 16, 2016 10:29:47 Sven Eckelmann wrote:
> batman-adv uses a self-written reference implementation which is just based
> on atomic_t. This is less obvious when reading the code than kref and
> therefore increases the change that the reference counting will be missed.
>
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> ---
> v6:
> - removed patches which are now applied in the branch next
> - rebased remaining patches on the patch
> "batman-adv: Avoid recursive call_rcu for batadv_nc_node" which was
> modified by Marek while he applied the patches (this unfortunately made
> some of the remaining patches "hard" to apply)
> v5:
> - add hack which allows to compile against stable kernel like 3.2.44 which
> also added the kref_get_unless_zero function
> v4:
> - fix function names in commit messages
> - fix double whitespace in batadv_tt_orig_list_entry_release kerneldoc
> - add extra patch for batadv_claim_free_ref kerneldoc fix
> - change the phrase "free it" in all *_free_ref/*_put functions to "release
> it" v3:
> - update copyright year
> v2:
> - split patchset into fixes and kref migration to make it easier when the
> decision is made where each patch will be applied
>
> net/batman-adv/distributed-arp-table.c | 27 +++++++++++++++++++++------
> net/batman-adv/types.h | 2 +-
> 2 files changed, 22 insertions(+), 7 deletions(-)
Applied in revision 4952250.
Thanks,
Marek
@@ -30,6 +30,7 @@
#include <linux/in.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
+#include <linux/kref.h>
#include <linux/list.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
@@ -62,14 +63,27 @@ static void batadv_dat_start_timer(struct batadv_priv *bat_priv)
}
/**
+ * batadv_dat_entry_release - release dat_entry from lists and queue for free
+ * after rcu grace period
+ * @ref: kref pointer of the dat_entry
+ */
+static void batadv_dat_entry_release(struct kref *ref)
+{
+ struct batadv_dat_entry *dat_entry;
+
+ dat_entry = container_of(ref, struct batadv_dat_entry, refcount);
+
+ kfree_rcu(dat_entry, rcu);
+}
+
+/**
* batadv_dat_entry_free_ref - decrement the dat_entry refcounter and possibly
- * free it
- * @dat_entry: the entry to free
+ * release it
+ * @dat_entry: dat_entry to be free'd
*/
static void batadv_dat_entry_free_ref(struct batadv_dat_entry *dat_entry)
{
- if (atomic_dec_and_test(&dat_entry->refcount))
- kfree_rcu(dat_entry, rcu);
+ kref_put(&dat_entry->refcount, batadv_dat_entry_release);
}
/**
@@ -281,7 +295,7 @@ batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
if (dat_entry->ip != ip)
continue;
- if (!atomic_inc_not_zero(&dat_entry->refcount))
+ if (!kref_get_unless_zero(&dat_entry->refcount))
continue;
dat_entry_tmp = dat_entry;
@@ -326,7 +340,8 @@ static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
dat_entry->vid = vid;
ether_addr_copy(dat_entry->mac_addr, mac_addr);
dat_entry->last_update = jiffies;
- atomic_set(&dat_entry->refcount, 2);
+ kref_init(&dat_entry->refcount);
+ kref_get(&dat_entry->refcount);
hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
batadv_hash_dat, dat_entry,
@@ -1230,7 +1230,7 @@ struct batadv_dat_entry {
unsigned short vid;
unsigned long last_update;
struct hlist_node hash_entry;
- atomic_t refcount;
+ struct kref refcount;
struct rcu_head rcu;
};