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authorOliver Hartkopp <socketcan@hartkopp.net>2022-05-20 20:32:39 +0200
committerMarc Kleine-Budde <mkl@pengutronix.de>2022-07-04 10:33:39 +0200
commitf1b4e32aca0811aa011c76e5d6cf2fa19224b386 (patch)
tree0f694194df3c23161ed53d97fb2a8b40436e9a6a /net
parent280e3a857d96f9ca8e24632788e1e7a0fec4e9f7 (diff)
can: bcm: use call_rcu() instead of costly synchronize_rcu()
In commit d5f9023fa61e ("can: bcm: delay release of struct bcm_op after synchronize_rcu()") Thadeu Lima de Souza Cascardo introduced two synchronize_rcu() calls in bcm_release() (only once at socket close) and in bcm_delete_rx_op() (called on removal of each single bcm_op). Unfortunately this slow removal of the bcm_op's affects user space applications like cansniffer where the modification of a filter removes 2048 bcm_op's which blocks the cansniffer application for 40(!) seconds. In commit 181d4447905d ("can: gw: use call_rcu() instead of costly synchronize_rcu()") Eric Dumazet replaced the synchronize_rcu() calls with several call_rcu()'s to safely remove the data structures after the removal of CAN ID subscriptions with can_rx_unregister() calls. This patch adopts Erics approach for the can-bcm which should be applicable since the removal of tasklet_kill() in bcm_remove_op() and the introduction of the HRTIMER_MODE_SOFT timer handling in Linux 5.4. Fixes: d5f9023fa61e ("can: bcm: delay release of struct bcm_op after synchronize_rcu()") # >= 5.4 Link: https://lore.kernel.org/all/20220520183239.19111-1-socketcan@hartkopp.net Cc: stable@vger.kernel.org Cc: Eric Dumazet <edumazet@google.com> Cc: Norbert Slusarek <nslusarek@gmx.net> Cc: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'net')
-rw-r--r--net/can/bcm.c18
1 files changed, 14 insertions, 4 deletions
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 65ee1b784a30..e60161bec850 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -100,6 +100,7 @@ static inline u64 get_u64(const struct canfd_frame *cp, int offset)
struct bcm_op {
struct list_head list;
+ struct rcu_head rcu;
int ifindex;
canid_t can_id;
u32 flags;
@@ -718,10 +719,9 @@ static struct bcm_op *bcm_find_op(struct list_head *ops,
return NULL;
}
-static void bcm_remove_op(struct bcm_op *op)
+static void bcm_free_op_rcu(struct rcu_head *rcu_head)
{
- hrtimer_cancel(&op->timer);
- hrtimer_cancel(&op->thrtimer);
+ struct bcm_op *op = container_of(rcu_head, struct bcm_op, rcu);
if ((op->frames) && (op->frames != &op->sframe))
kfree(op->frames);
@@ -732,6 +732,14 @@ static void bcm_remove_op(struct bcm_op *op)
kfree(op);
}
+static void bcm_remove_op(struct bcm_op *op)
+{
+ hrtimer_cancel(&op->timer);
+ hrtimer_cancel(&op->thrtimer);
+
+ call_rcu(&op->rcu, bcm_free_op_rcu);
+}
+
static void bcm_rx_unreg(struct net_device *dev, struct bcm_op *op)
{
if (op->rx_reg_dev == dev) {
@@ -757,6 +765,9 @@ static int bcm_delete_rx_op(struct list_head *ops, struct bcm_msg_head *mh,
if ((op->can_id == mh->can_id) && (op->ifindex == ifindex) &&
(op->flags & CAN_FD_FRAME) == (mh->flags & CAN_FD_FRAME)) {
+ /* disable automatic timer on frame reception */
+ op->flags |= RX_NO_AUTOTIMER;
+
/*
* Don't care if we're bound or not (due to netdev
* problems) can_rx_unregister() is always a save
@@ -785,7 +796,6 @@ static int bcm_delete_rx_op(struct list_head *ops, struct bcm_msg_head *mh,
bcm_rx_handler, op);
list_del(&op->list);
- synchronize_rcu();
bcm_remove_op(op);
return 1; /* done */
}