diff options
author | Oliver Hartkopp <socketcan@hartkopp.net> | 2022-05-20 21:32:39 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-07-12 17:32:16 +0300 |
commit | 85cd41070df992d3c0dfd828866fdd243d3b774a (patch) | |
tree | a4b9802718cc9d369997d9618d59fdb99875e1a5 /net/can | |
parent | b75d4bec85b81109726c0a7d982067e766714509 (diff) | |
download | linux-85cd41070df992d3c0dfd828866fdd243d3b774a.tar.xz |
can: bcm: use call_rcu() instead of costly synchronize_rcu()
commit f1b4e32aca0811aa011c76e5d6cf2fa19224b386 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/can')
-rw-r--r-- | net/can/bcm.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/net/can/bcm.c b/net/can/bcm.c index 0928a39c4423..e918a0f3cda2 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 */ } |