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Date: Sat, 19 Aug 2023 11:19:56 +0200
From: Petr Pavlu <petr.pavlu@...e.com>
To: Leon Romanovsky <leon@...nel.org>
Cc: tariqt@...dia.com, yishaih@...dia.com, davem@...emloft.net,
edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, jgg@...pe.ca,
netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 03/10] mlx4: Replace the mlx4_interface.event
callback with a notifier
On 8/13/23 18:54, Leon Romanovsky wrote:
> On Sun, Aug 13, 2023 at 04:51:20PM +0200, Petr Pavlu wrote:
>> Use a notifier to implement mlx4_dispatch_event() in preparation to
>> switch mlx4_en and mlx4_ib to be an auxiliary device.
>>
>> A problem is that if the mlx4_interface.event callback was replaced with
>> something as mlx4_adrv.event then the implementation of
>> mlx4_dispatch_event() would need to acquire a lock on a given device
>> before executing this callback. That is necessary because otherwise
>> there is no guarantee that the associated driver cannot get unbound when
>> the callback is running. However, taking this lock is not possible
>> because mlx4_dispatch_event() can be invoked from the hardirq context.
>> Using an atomic notifier allows the driver to accurately record when it
>> wants to receive these events and solves this problem.
>>
>> A handler registration is done by both mlx4_en and mlx4_ib at the end of
>> their mlx4_interface.add callback. This matches the current situation
>> when mlx4_add_device() would enable events for a given device
>> immediately after this callback, by adding the device on the
>> mlx4_priv.list.
>>
>> Signed-off-by: Petr Pavlu <petr.pavlu@...e.com>
>> Tested-by: Leon Romanovsky <leonro@...dia.com>
>> Acked-by: Tariq Toukan <tariqt@...dia.com>
>> ---
>> drivers/infiniband/hw/mlx4/main.c | 41 +++++++++++++-------
>> drivers/infiniband/hw/mlx4/mlx4_ib.h | 2 +
>> drivers/net/ethernet/mellanox/mlx4/en_main.c | 27 +++++++++----
>> drivers/net/ethernet/mellanox/mlx4/intf.c | 24 ++++++++----
>> drivers/net/ethernet/mellanox/mlx4/main.c | 2 +
>> drivers/net/ethernet/mellanox/mlx4/mlx4.h | 2 +
>> drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 2 +
>> include/linux/mlx4/driver.h | 8 +++-
>> 8 files changed, 77 insertions(+), 31 deletions(-)
>>
>> diff --git a/drivers/infiniband/hw/mlx4/main.c b/drivers/infiniband/hw/mlx4/main.c
>> index 7dd70d778b6b..0761c465120b 100644
>> --- a/drivers/infiniband/hw/mlx4/main.c
>> +++ b/drivers/infiniband/hw/mlx4/main.c
>> @@ -82,6 +82,8 @@ static const char mlx4_ib_version[] =
>> static void do_slave_init(struct mlx4_ib_dev *ibdev, int slave, int do_init);
>> static enum rdma_link_layer mlx4_ib_port_link_layer(struct ib_device *device,
>> u32 port_num);
>> +static int mlx4_ib_event(struct notifier_block *this, unsigned long event,
>> + void *ptr);
>>
>> static struct workqueue_struct *wq;
>>
>> @@ -2836,6 +2838,12 @@ static void *mlx4_ib_add(struct mlx4_dev *dev)
>> do_slave_init(ibdev, j, 1);
>> }
>> }
>> +
>> + /* register mlx4 core notifier */
>> + ibdev->mlx_nb.notifier_call = mlx4_ib_event;
>> + err = mlx4_register_event_notifier(dev, &ibdev->mlx_nb);
>> + WARN(err, "failed to register mlx4 event notifier (%d)", err);
>> +
>> return ibdev;
>>
>> err_notif:
>> @@ -2953,6 +2961,8 @@ static void mlx4_ib_remove(struct mlx4_dev *dev, void *ibdev_ptr)
>> int p;
>> int i;
>>
>> + mlx4_unregister_event_notifier(dev, &ibdev->mlx_nb);
>> +
>> mlx4_foreach_port(i, dev, MLX4_PORT_TYPE_IB)
>> devlink_port_type_clear(mlx4_get_devlink_port(dev, i));
>> ibdev->ib_active = false;
>> @@ -3173,11 +3183,14 @@ void mlx4_sched_ib_sl2vl_update_work(struct mlx4_ib_dev *ibdev,
>> }
>> }
>>
>> -static void mlx4_ib_event(struct mlx4_dev *dev, void *ibdev_ptr,
>> - enum mlx4_dev_event event, unsigned long param)
>> +static int mlx4_ib_event(struct notifier_block *this, unsigned long event,
>> + void *ptr)
>> {
>> + struct mlx4_ib_dev *ibdev =
>> + container_of(this, struct mlx4_ib_dev, mlx_nb);
>> + struct mlx4_dev *dev = ibdev->dev;
>> + unsigned long param = *(unsigned long *)ptr;
>
> You don't need this assignment here as later, you will cast param again,
> in your next patches:
>
> 3227 if (event == MLX4_DEV_EVENT_PORT_MGMT_CHANGE)
> 3228 eqe = (struct mlx4_eqe *)param;
> 3229 else
> 3230 p = (int) param;
>
> so use ptr directly:
>
> if (event == MLX4_DEV_EVENT_PORT_MGMT_CHANGE)
> eqe = param;
> else
> p = *(int *) param;
Function mlx4_dispatch_event() currently takes an 'unsigned long' as its
event parameter. The patch updates the function to use
atomic_notifier_call_chain() which however expects 'void *' as the
'param' value. To solve the mismatch, mlx4_dispatch_event() passes to
atomic_notifier_call_chain() an address of the original 'param'. This
creates one additional level of indirection which the handlers, such as
mlx4_ib_event(), need to deal with. Line
'unsigned long param = *(unsigned long *)ptr;' is added for that.
I think the best way to avoid this complexity would be for
mlx4_dispatch_event() to take 'void *' as its 'param' in the first
place. I would add the following patch before this one in v3 of the
series.
>From e17d6b8fb32e6caeba2929764ad0249a2e136049 Mon Sep 17 00:00:00 2001
From: Petr Pavlu <petr.pavlu@...e.com>
Date: Fri, 18 Aug 2023 12:55:30 +0200
Subject: [PATCH] mlx4: Use 'void *' as the event param of
mlx4_dispatch_event()
Function mlx4_dispatch_event() takes an 'unsigned long' as its event
parameter. The actual value is none (MLX4_DEV_EVENT_CATASTROPHIC_ERROR),
a pointer to mlx4_eqe (MLX4_DEV_EVENT_PORT_MGMT_CHANGE), or a 32-bit
integer (remaining events).
In preparation to switch mlx4_en and mlx4_ib to be an auxiliary device,
the mlx4_interface.event callback is replaced with a notifier and
function mlx4_dispatch_event() gets updated to invoke
atomic_notifier_call_chain(). This requires forwarding the input 'param'
value from the former function to the latter. A problem is that the
notifier call takes 'void *' as its 'param' value, compared to
'unsigned long' used by mlx4_dispatch_event(). Re-passing the value
would need either punning it to 'void *' or passing down the address of
the input 'param'. Both approaches create a number of unnecessary casts.
Change instead the input 'param' of mlx4_dispatch_event() from
'unsigned long' to 'void *'. A mlx4_eqe pointer can be passed directly,
callers using an int value are adjusted to pass its address.
Signed-off-by: Petr Pavlu <petr.pavlu@...e.com>
---
drivers/infiniband/hw/mlx4/main.c | 14 ++++++++++----
drivers/net/ethernet/mellanox/mlx4/catas.c | 2 +-
drivers/net/ethernet/mellanox/mlx4/cmd.c | 4 ++--
drivers/net/ethernet/mellanox/mlx4/en_main.c | 17 +++++++++++++++--
drivers/net/ethernet/mellanox/mlx4/eq.c | 15 ++++++++-------
drivers/net/ethernet/mellanox/mlx4/intf.c | 2 +-
drivers/net/ethernet/mellanox/mlx4/mlx4.h | 2 +-
include/linux/mlx4/driver.h | 2 +-
8 files changed, 39 insertions(+), 19 deletions(-)
diff --git a/drivers/infiniband/hw/mlx4/main.c b/drivers/infiniband/hw/mlx4/main.c
index 7dd70d778b6b..2c5fd8174b3c 100644
--- a/drivers/infiniband/hw/mlx4/main.c
+++ b/drivers/infiniband/hw/mlx4/main.c
@@ -3174,7 +3174,7 @@ void mlx4_sched_ib_sl2vl_update_work(struct mlx4_ib_dev *ibdev,
}
static void mlx4_ib_event(struct mlx4_dev *dev, void *ibdev_ptr,
- enum mlx4_dev_event event, unsigned long param)
+ enum mlx4_dev_event event, void *param)
{
struct ib_event ibev;
struct mlx4_ib_dev *ibdev = to_mdev((struct ib_device *) ibdev_ptr);
@@ -3194,10 +3194,16 @@ static void mlx4_ib_event(struct mlx4_dev *dev, void *ibdev_ptr,
return;
}
- if (event == MLX4_DEV_EVENT_PORT_MGMT_CHANGE)
+ switch (event) {
+ case MLX4_DEV_EVENT_CATASTROPHIC_ERROR:
+ break;
+ case MLX4_DEV_EVENT_PORT_MGMT_CHANGE:
eqe = (struct mlx4_eqe *)param;
- else
- p = (int) param;
+ break;
+ default:
+ p = *(int *)param;
+ break;
+ }
switch (event) {
case MLX4_DEV_EVENT_PORT_UP:
diff --git a/drivers/net/ethernet/mellanox/mlx4/catas.c b/drivers/net/ethernet/mellanox/mlx4/catas.c
index 0eb7b83637d8..0d8a362c2673 100644
--- a/drivers/net/ethernet/mellanox/mlx4/catas.c
+++ b/drivers/net/ethernet/mellanox/mlx4/catas.c
@@ -194,7 +194,7 @@ void mlx4_enter_error_state(struct mlx4_dev_persistent *persist)
mutex_unlock(&persist->device_state_mutex);
/* At that step HW was already reset, now notify clients */
- mlx4_dispatch_event(dev, MLX4_DEV_EVENT_CATASTROPHIC_ERROR, 0);
+ mlx4_dispatch_event(dev, MLX4_DEV_EVENT_CATASTROPHIC_ERROR, NULL);
mlx4_cmd_wake_completions(dev);
return;
diff --git a/drivers/net/ethernet/mellanox/mlx4/cmd.c b/drivers/net/ethernet/mellanox/mlx4/cmd.c
index c56d2194cbfc..f5b1f8c7834f 100644
--- a/drivers/net/ethernet/mellanox/mlx4/cmd.c
+++ b/drivers/net/ethernet/mellanox/mlx4/cmd.c
@@ -2113,7 +2113,7 @@ static void mlx4_master_do_cmd(struct mlx4_dev *dev, int slave, u8 cmd,
if (MLX4_COMM_CMD_FLR == slave_state[slave].last_cmd)
goto inform_slave_state;
- mlx4_dispatch_event(dev, MLX4_DEV_EVENT_SLAVE_SHUTDOWN, slave);
+ mlx4_dispatch_event(dev, MLX4_DEV_EVENT_SLAVE_SHUTDOWN, &slave);
/* write the version in the event field */
reply |= mlx4_comm_get_version();
@@ -2152,7 +2152,7 @@ static void mlx4_master_do_cmd(struct mlx4_dev *dev, int slave, u8 cmd,
if (mlx4_master_activate_admin_state(priv, slave))
goto reset_slave;
slave_state[slave].active = true;
- mlx4_dispatch_event(dev, MLX4_DEV_EVENT_SLAVE_INIT, slave);
+ mlx4_dispatch_event(dev, MLX4_DEV_EVENT_SLAVE_INIT, &slave);
break;
case MLX4_COMM_CMD_VHCR_POST:
if ((slave_state[slave].last_cmd != MLX4_COMM_CMD_VHCR_EN) &&
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_main.c b/drivers/net/ethernet/mellanox/mlx4/en_main.c
index be8ba34c9025..83dae886ade6 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_main.c
@@ -184,10 +184,22 @@ static void mlx4_en_get_profile(struct mlx4_en_dev *mdev)
}
static void mlx4_en_event(struct mlx4_dev *dev, void *endev_ptr,
- enum mlx4_dev_event event, unsigned long port)
+ enum mlx4_dev_event event, void *param)
{
struct mlx4_en_dev *mdev = (struct mlx4_en_dev *) endev_ptr;
struct mlx4_en_priv *priv;
+ int port;
+
+ switch (event) {
+ case MLX4_DEV_EVENT_CATASTROPHIC_ERROR:
+ case MLX4_DEV_EVENT_PORT_MGMT_CHANGE:
+ case MLX4_DEV_EVENT_SLAVE_INIT:
+ case MLX4_DEV_EVENT_SLAVE_SHUTDOWN:
+ break;
+ default:
+ port = *(int *)param;
+ break;
+ }
switch (event) {
case MLX4_DEV_EVENT_PORT_UP:
@@ -205,6 +217,7 @@ static void mlx4_en_event(struct mlx4_dev *dev, void *endev_ptr,
mlx4_err(mdev, "Internal error detected, restarting device\n");
break;
+ case MLX4_DEV_EVENT_PORT_MGMT_CHANGE:
case MLX4_DEV_EVENT_SLAVE_INIT:
case MLX4_DEV_EVENT_SLAVE_SHUTDOWN:
break;
@@ -213,7 +226,7 @@ static void mlx4_en_event(struct mlx4_dev *dev, void *endev_ptr,
!mdev->pndev[port])
return;
mlx4_warn(mdev, "Unhandled event %d for port %d\n", event,
- (int) port);
+ port);
}
}
diff --git a/drivers/net/ethernet/mellanox/mlx4/eq.c b/drivers/net/ethernet/mellanox/mlx4/eq.c
index 414e390e6b48..6598b10a9ff4 100644
--- a/drivers/net/ethernet/mellanox/mlx4/eq.c
+++ b/drivers/net/ethernet/mellanox/mlx4/eq.c
@@ -501,7 +501,7 @@ static int mlx4_eq_int(struct mlx4_dev *dev, struct mlx4_eq *eq)
int port;
int slave = 0;
int ret;
- u32 flr_slave;
+ int flr_slave;
u8 update_slave_state;
int i;
enum slave_port_gen_event gen_event;
@@ -606,8 +606,8 @@ static int mlx4_eq_int(struct mlx4_dev *dev, struct mlx4_eq *eq)
port = be32_to_cpu(eqe->event.port_change.port) >> 28;
slaves_port = mlx4_phys_to_slaves_pport(dev, port);
if (eqe->subtype == MLX4_PORT_CHANGE_SUBTYPE_DOWN) {
- mlx4_dispatch_event(dev, MLX4_DEV_EVENT_PORT_DOWN,
- port);
+ mlx4_dispatch_event(
+ dev, MLX4_DEV_EVENT_PORT_DOWN, &port);
mlx4_priv(dev)->sense.do_sense_port[port] = 1;
if (!mlx4_is_master(dev))
break;
@@ -647,7 +647,8 @@ static int mlx4_eq_int(struct mlx4_dev *dev, struct mlx4_eq *eq)
}
}
} else {
- mlx4_dispatch_event(dev, MLX4_DEV_EVENT_PORT_UP, port);
+ mlx4_dispatch_event(dev, MLX4_DEV_EVENT_PORT_UP,
+ &port);
mlx4_priv(dev)->sense.do_sense_port[port] = 0;
@@ -758,7 +759,7 @@ static int mlx4_eq_int(struct mlx4_dev *dev, struct mlx4_eq *eq)
}
spin_unlock_irqrestore(&priv->mfunc.master.slave_state_lock, flags);
mlx4_dispatch_event(dev, MLX4_DEV_EVENT_SLAVE_SHUTDOWN,
- flr_slave);
+ &flr_slave);
queue_work(priv->mfunc.master.comm_wq,
&priv->mfunc.master.slave_flr_event_work);
break;
@@ -787,8 +788,8 @@ static int mlx4_eq_int(struct mlx4_dev *dev, struct mlx4_eq *eq)
break;
case MLX4_EVENT_TYPE_PORT_MNG_CHG_EVENT:
- mlx4_dispatch_event(dev, MLX4_DEV_EVENT_PORT_MGMT_CHANGE,
- (unsigned long) eqe);
+ mlx4_dispatch_event(
+ dev, MLX4_DEV_EVENT_PORT_MGMT_CHANGE, eqe);
break;
case MLX4_EVENT_TYPE_RECOVERABLE_ERROR_EVENT:
diff --git a/drivers/net/ethernet/mellanox/mlx4/intf.c b/drivers/net/ethernet/mellanox/mlx4/intf.c
index 28d7da925d36..a761971cd0c4 100644
--- a/drivers/net/ethernet/mellanox/mlx4/intf.c
+++ b/drivers/net/ethernet/mellanox/mlx4/intf.c
@@ -180,7 +180,7 @@ int mlx4_do_bond(struct mlx4_dev *dev, bool enable)
}
void mlx4_dispatch_event(struct mlx4_dev *dev, enum mlx4_dev_event type,
- unsigned long param)
+ void *param)
{
struct mlx4_priv *priv = mlx4_priv(dev);
struct mlx4_device_context *dev_ctx;
diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4.h b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
index 6ccf340660d9..de5699a4ddaa 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
@@ -1048,7 +1048,7 @@ int mlx4_restart_one(struct pci_dev *pdev);
int mlx4_register_device(struct mlx4_dev *dev);
void mlx4_unregister_device(struct mlx4_dev *dev);
void mlx4_dispatch_event(struct mlx4_dev *dev, enum mlx4_dev_event type,
- unsigned long param);
+ void *param);
struct mlx4_dev_cap;
struct mlx4_init_hca_param;
diff --git a/include/linux/mlx4/driver.h b/include/linux/mlx4/driver.h
index 923951e19300..032d7f5bfef6 100644
--- a/include/linux/mlx4/driver.h
+++ b/include/linux/mlx4/driver.h
@@ -58,7 +58,7 @@ struct mlx4_interface {
void * (*add) (struct mlx4_dev *dev);
void (*remove)(struct mlx4_dev *dev, void *context);
void (*event) (struct mlx4_dev *dev, void *context,
- enum mlx4_dev_event event, unsigned long param);
+ enum mlx4_dev_event event, void *param);
void (*activate)(struct mlx4_dev *dev, void *context);
struct list_head list;
enum mlx4_protocol protocol;
--
2.35.3
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