Re: [PATCH net-next v1] netdevsim: Forbid devlink reload when adding or deleting ports
From: Leon Romanovsky <leon@kernel.org>
Date: 2021-08-05 13:51:39
Also in:
lkml
Subsystem:
netdevsim, networking drivers, the rest · Maintainers:
Jakub Kicinski, Andrew Lunn, "David S. Miller", Eric Dumazet, Paolo Abeni, Linus Torvalds
On Thu, Aug 05, 2021 at 06:15:47AM -0700, Jakub Kicinski wrote:
On Thu, 5 Aug 2021 14:05:41 +0300 Leon Romanovsky wrote:quoted
From: Leon Romanovsky <leonro@nvidia.com> In order to remove complexity in devlink core related to devlink_reload_enable/disable, let's rewrite new_port/del_port logic to rely on internal to netdevsim lock. We should protect only reload_down flow because it destroys nsim_dev, which is needed for nsim_dev_port_add/nsim_dev_port_del to hold port_list_lock.I don't understand why we only have to protect reload_down.
I assumed that if we succeeded to pass reload_down and we are in reload_up stage, everything was already bailed out.
What protects us from adding a port right after down? That'd hit a destroyed mutex, up wipes the port list etc...
You will have very similar crash to already existing one: * parallel call to del_device and add_port will hit same issue. The idea is not make netdevsim universally correct, but to ensure that it doesn't crash immediately.
quoted
+ nsim_bus_dev = nsim_dev->nsim_bus_dev; + if (!mutex_trylock(&nsim_bus_dev->nsim_bus_reload_lock)) + return -EOPNOTSUPP;Why not -EBUSY?
This is what devlink_reload_disable() returns, so I kept same error. It is not important at all. What about the following change on top of this patch?
diff --git a/drivers/net/netdevsim/bus.c b/drivers/net/netdevsim/bus.c
index a29ec264119d..62d033a1a557 100644
--- a/drivers/net/netdevsim/bus.c
+++ b/drivers/net/netdevsim/bus.c@@ -196,6 +196,11 @@ new_port_store(struct device *dev, struct device_attribute *attr, if (!mutex_trylock(&nsim_bus_dev->nsim_bus_reload_lock)) return -EBUSY; + if (nsim_bus_dev->in_reload) { + mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock); + return -EBUSY; + } + ret = nsim_dev_port_add(nsim_bus_dev, NSIM_DEV_PORT_TYPE_PF, port_index); mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock); return ret ? ret : count;
@@ -221,6 +226,11 @@ del_port_store(struct device *dev, struct device_attribute *attr, if (!mutex_trylock(&nsim_bus_dev->nsim_bus_reload_lock)) return -EBUSY; + if (nsim_bus_dev->in_reload) { + mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock); + return -EBUSY; + } + ret = nsim_dev_port_del(nsim_bus_dev, NSIM_DEV_PORT_TYPE_PF, port_index); mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock); return ret ? ret : count;
diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
index ff5714209b86..53068e184c90 100644
--- a/drivers/net/netdevsim/dev.c
+++ b/drivers/net/netdevsim/dev.c@@ -878,6 +878,7 @@ static int nsim_dev_reload_down(struct devlink *devlink, bool netns_change, mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock); return -EOPNOTSUPP; } + nsim_bus_dev->in_reload = true; nsim_dev_reload_destroy(nsim_dev); mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock);
@@ -889,17 +890,26 @@ static int nsim_dev_reload_up(struct devlink *devlink, enum devlink_reload_actio struct netlink_ext_ack *extack) { struct nsim_dev *nsim_dev = devlink_priv(devlink); + struct nsim_bus_dev *nsim_bus_dev; + int ret; + + nsim_bus_dev = nsim_dev->nsim_bus_dev; + mutex_lock(&nsim_bus_dev->nsim_bus_reload_lock); + nsim_bus_dev->in_reload = false; if (nsim_dev->fail_reload) { /* For testing purposes, user set debugfs fail_reload * value to true. Fail right away. */ NL_SET_ERR_MSG_MOD(extack, "User setup the reload to fail for testing purposes"); + mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock); return -EINVAL; } *actions_performed = BIT(DEVLINK_RELOAD_ACTION_DRIVER_REINIT); - return nsim_dev_reload_create(nsim_dev, extack); + ret = nsim_dev_reload_create(nsim_dev, extack); + mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock); + return ret; } static int nsim_dev_info_get(struct devlink *devlink,
diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index 1c20bcbd9d91..793c86dc5a9c 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h@@ -362,6 +362,7 @@ struct nsim_bus_dev { struct nsim_vf_config *vfconfigs; /* Lock for devlink->reload_enabled in netdevsim module */ struct mutex nsim_bus_reload_lock; + bool in_reload; bool init; };
Thanks