drivers/infiniband/core/device.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-)
The mad_client will be initialized in enable_device_and_get(), while the
devices_rwsem will be downgraded to a read semaphore. There is a window
that leads to the failed initialization for cm_client, since it can not
get matched mad port from ib_mad_port_list, and the matched mad port will
be added to the list after that.
mad_client | cm_client
------------------|--------------------------------------------------------
ib_register_device|
enable_device_and_get
down_write(&devices_rwsem)
xa_set_mark(&devices, DEVICE_REGISTERED)
downgrade_write(&devices_rwsem)
|
|ib_cm_init
|ib_register_client(&cm_client)
|down_read(&devices_rwsem)
|xa_for_each_marked (&devices, DEVICE_REGISTERED)
|add_client_context
|cm_add_one
|ib_register_mad_agent
|ib_get_mad_port
|__ib_get_mad_port
|list_for_each_entry(entry, &ib_mad_port_list, port_list)
|return NULL
|up_read(&devices_rwsem)
|
add_client_context|
ib_mad_init_device|
ib_mad_port_open |
list_add_tail(&port_priv->port_list, &ib_mad_port_list)
up_read(&devices_rwsem)
|
Fix it by using the devices_rwsem write semaphore to protect the mad_client
init flow in enable_device_and_get().
Fixes: d0899892edd0 ("RDMA/device: Provide APIs from the core code to help unregistration")
Cc: Shifeng Li <lishifeng1992@126.com>
Signed-off-by: Shifeng Li <lishifeng@sangfor.com.cn>
---
drivers/infiniband/core/device.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index 67bcea7a153c..85782786993d 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -1315,12 +1315,6 @@ static int enable_device_and_get(struct ib_device *device)
down_write(&devices_rwsem);
xa_set_mark(&devices, device->index, DEVICE_REGISTERED);
- /*
- * By using downgrade_write() we ensure that no other thread can clear
- * DEVICE_REGISTERED while we are completing the client setup.
- */
- downgrade_write(&devices_rwsem);
-
if (device->ops.enable_driver) {
ret = device->ops.enable_driver(device);
if (ret)
@@ -1337,7 +1331,7 @@ static int enable_device_and_get(struct ib_device *device)
if (!ret)
ret = add_compat_devs(device);
out:
- up_read(&devices_rwsem);
+ up_write(&devices_rwsem);
return ret;
}
--
2.25.1On Mon, Jan 01, 2024 at 07:43:35PM -0800, Shifeng Li wrote:
> diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
> index 67bcea7a153c..85782786993d 100644
> --- a/drivers/infiniband/core/device.c
> +++ b/drivers/infiniband/core/device.c
> @@ -1315,12 +1315,6 @@ static int enable_device_and_get(struct ib_device *device)
> down_write(&devices_rwsem);
> xa_set_mark(&devices, device->index, DEVICE_REGISTERED);
>
> - /*
> - * By using downgrade_write() we ensure that no other thread can clear
> - * DEVICE_REGISTERED while we are completing the client setup.
> - */
> - downgrade_write(&devices_rwsem);
> -
> if (device->ops.enable_driver) {
> ret = device->ops.enable_driver(device);
> if (ret)
> @@ -1337,7 +1331,7 @@ static int enable_device_and_get(struct ib_device *device)
> if (!ret)
> ret = add_compat_devs(device);
> out:
> - up_read(&devices_rwsem);
> + up_write(&devices_rwsem);
> return ret;
> }
I don't think messing with the devices_rwsem here is a great idea, it
would be better to address this on the clients_rwsem side like:
diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index 67bcea7a153c6a..b956c9f8e62d34 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -1730,7 +1730,7 @@ static int assign_client_id(struct ib_client *client)
{
int ret;
- down_write(&clients_rwsem);
+ lockdep_assert_held(&clients_rwsem);
/*
* The add/remove callbacks must be called in FIFO/LIFO order. To
* achieve this we assign client_ids so they are sorted in
@@ -1739,14 +1739,11 @@ static int assign_client_id(struct ib_client *client)
client->client_id = highest_client_id;
ret = xa_insert(&clients, client->client_id, client, GFP_KERNEL);
if (ret)
- goto out;
+ return ret;
highest_client_id++;
xa_set_mark(&clients, client->client_id, CLIENT_REGISTERED);
-
-out:
- up_write(&clients_rwsem);
- return ret;
+ return 0;
}
static void remove_client_id(struct ib_client *client)
@@ -1776,25 +1773,31 @@ int ib_register_client(struct ib_client *client)
{
struct ib_device *device;
unsigned long index;
+ bool need_unreg = false;
int ret;
refcount_set(&client->uses, 1);
init_completion(&client->uses_zero);
- ret = assign_client_id(client);
- if (ret)
- return ret;
down_read(&devices_rwsem);
+ down_write(&clients_rwsem);
+ ret = assign_client_id(client);
+ if (ret)
+ goto out;
+
+ need_unreg = true;
xa_for_each_marked (&devices, index, device, DEVICE_REGISTERED) {
ret = add_client_context(device, client);
- if (ret) {
- up_read(&devices_rwsem);
- ib_unregister_client(client);
- return ret;
- }
+ if (ret)
+ goto out;
}
+ ret = 0;
+out:
+ up_write(&clients_rwsem);
up_read(&devices_rwsem);
- return 0;
+ if (need_unreg && ret)
+ ib_unregister_client(client);
+ return ret;
}
EXPORT_SYMBOL(ib_register_client);
On Mon, Jan 01, 2024 at 07:43:35PM -0800, Shifeng Li wrote:
> The mad_client will be initialized in enable_device_and_get(), while the
> devices_rwsem will be downgraded to a read semaphore. There is a window
> that leads to the failed initialization for cm_client, since it can not
> get matched mad port from ib_mad_port_list, and the matched mad port will
> be added to the list after that.
>
> mad_client | cm_client
> ------------------|--------------------------------------------------------
> ib_register_device|
> enable_device_and_get
> down_write(&devices_rwsem)
> xa_set_mark(&devices, DEVICE_REGISTERED)
> downgrade_write(&devices_rwsem)
> |
> |ib_cm_init
> |ib_register_client(&cm_client)
> |down_read(&devices_rwsem)
> |xa_for_each_marked (&devices, DEVICE_REGISTERED)
> |add_client_context
> |cm_add_one
> |ib_register_mad_agent
> |ib_get_mad_port
> |__ib_get_mad_port
> |list_for_each_entry(entry, &ib_mad_port_list, port_list)
> |return NULL
> |up_read(&devices_rwsem)
> |
> add_client_context|
> ib_mad_init_device|
> ib_mad_port_open |
> list_add_tail(&port_priv->port_list, &ib_mad_port_list)
> up_read(&devices_rwsem)
> |
How is this stack possible?
ib_register_device() is called by drivers and happens much later than ib_cm_init().
Thanks
>
> Fix it by using the devices_rwsem write semaphore to protect the mad_client
> init flow in enable_device_and_get().
>
> Fixes: d0899892edd0 ("RDMA/device: Provide APIs from the core code to help unregistration")
> Cc: Shifeng Li <lishifeng1992@126.com>
> Signed-off-by: Shifeng Li <lishifeng@sangfor.com.cn>
> ---
> drivers/infiniband/core/device.c | 8 +-------
> 1 file changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
> index 67bcea7a153c..85782786993d 100644
> --- a/drivers/infiniband/core/device.c
> +++ b/drivers/infiniband/core/device.c
> @@ -1315,12 +1315,6 @@ static int enable_device_and_get(struct ib_device *device)
> down_write(&devices_rwsem);
> xa_set_mark(&devices, device->index, DEVICE_REGISTERED);
>
> - /*
> - * By using downgrade_write() we ensure that no other thread can clear
> - * DEVICE_REGISTERED while we are completing the client setup.
> - */
> - downgrade_write(&devices_rwsem);
> -
> if (device->ops.enable_driver) {
> ret = device->ops.enable_driver(device);
> if (ret)
> @@ -1337,7 +1331,7 @@ static int enable_device_and_get(struct ib_device *device)
> if (!ret)
> ret = add_compat_devs(device);
> out:
> - up_read(&devices_rwsem);
> + up_write(&devices_rwsem);
> return ret;
> }
>
> --
> 2.25.1
>
>
On 2024/1/2 16:58, Leon Romanovsky wrote:
> On Mon, Jan 01, 2024 at 07:43:35PM -0800, Shifeng Li wrote:
>> The mad_client will be initialized in enable_device_and_get(), while the
>> devices_rwsem will be downgraded to a read semaphore. There is a window
>> that leads to the failed initialization for cm_client, since it can not
>> get matched mad port from ib_mad_port_list, and the matched mad port will
>> be added to the list after that.
>>
>> mad_client | cm_client
>> ------------------|--------------------------------------------------------
>> ib_register_device|
>> enable_device_and_get
>> down_write(&devices_rwsem)
>> xa_set_mark(&devices, DEVICE_REGISTERED)
>> downgrade_write(&devices_rwsem)
>> |
>> |ib_cm_init
>> |ib_register_client(&cm_client)
>> |down_read(&devices_rwsem)
>> |xa_for_each_marked (&devices, DEVICE_REGISTERED)
>> |add_client_context
>> |cm_add_one
>> |ib_register_mad_agent
>> |ib_get_mad_port
>> |__ib_get_mad_port
>> |list_for_each_entry(entry, &ib_mad_port_list, port_list)
>> |return NULL
>> |up_read(&devices_rwsem)
>> |
>> add_client_context|
>> ib_mad_init_device|
>> ib_mad_port_open |
>> list_add_tail(&port_priv->port_list, &ib_mad_port_list)
>> up_read(&devices_rwsem)
>> |
>
> How is this stack possible?
>
> ib_register_device() is called by drivers and happens much later than ib_cm_init().
>
I've caught the stack and err log as follows, ib_mad_init_device() called after
cm_add_one().
[ 98.281786] CPU: 18 PID: 30079 Comm: modprobe Kdump: loaded
[ 98.281787] Call Trace:
[ 98.281790] dump_stack+0x71/0xab
[ 98.281805] ib_register_mad_agent+0x1c6/0x27f0 [ib_core]
[ 98.281840] cm_add_one+0x4b0/0x9d0 [ib_cm]
[ 98.281865] add_client_context+0x2b9/0x380 [ib_core]
[ 98.281890] ib_register_client+0x22a/0x2a0 [ib_core]
[ 98.281908] __init_backport+0x12f/0x1000 [ib_cm]
[ 98.281912] do_one_initcall+0x87/0x2e2
[ 98.281926] do_init_module+0x1c3/0x5f7
[ 98.281928] load_module+0x4fe0/0x68d0
[ 98.281945] __do_sys_finit_module+0x14d/0x180
[ 98.281952] do_syscall_64+0xa0/0x370
[ 98.281957] entry_SYSCALL_64_after_hwframe+0x65/0xca
[ 98.281958] RIP: 0033:0x7f51d3a4373d
[ 98.281961] RSP: 002b:00007ffceb925938 EFLAGS: 00000202 ORIG_RAX: 0000000000000139
[ 98.281964] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f51d3a4373d
[ 98.281965] RDX: 0000000000000000 RSI: 0000000001636b70 RDI: 0000000000000003
[ 98.281966] RBP: 00007ffceb925950 R08: 0000000000000000 R09: 0000000001636b70
[ 98.281967] R10: 0000000000000003 R11: 0000000000000202 R12: 0000000000402410
[ 98.281968] R13: 00007ffceb926e60 R14: 0000000000000000 R15: 0000000000000000
[ 98.281977] infiniband mlx5_1: ib_register_mad_agent: Invalid port 1
[ 98.349040] CPU: 38 PID: 29896 Comm: modprobe Kdump: loaded
[ 98.349043] Call Trace:
[ 98.349053] dump_stack+0x71/0xab
[ 98.349076] ib_register_mad_agent+0x1c6/0x27f0 [ib_core]
[ 98.349149] ib_agent_port_open+0xe2/0x2d0 [ib_core]
[ 98.349164] ib_mad_init_device+0x818/0x1d70 [ib_core]
[ 98.349197] add_client_context+0x2b9/0x380 [ib_core]
[ 98.349221] enable_device_and_get+0x1ab/0x340 [ib_core]
[ 98.349292] ib_register_device+0xcbf/0xfd0 [ib_core]
[ 98.349355] __mlx5_ib_add+0x44/0xf0 [mlx5_ib]
[ 98.349404] mlx5_add_device+0xc3/0x280 [mlx5_core]
[ 98.349434] mlx5_register_interface+0x109/0x190 [mlx5_core]
[ 98.349442] do_one_initcall+0x87/0x2e2
[ 98.349460] do_init_module+0x1c3/0x5f7
[ 98.349462] load_module+0x4fe0/0x68d0
[ 98.349481] __do_sys_init_module+0x1f9/0x220
[ 98.349486] do_syscall_64+0xa0/0x370
[ 98.349492] entry_SYSCALL_64_after_hwframe+0x65/0xca
[ 98.349494] RIP: 0033:0x7fbc327faa7a
[ 98.349500] RSP: 002b:00007fff890df7f8 EFLAGS: 00000202 ORIG_RAX: 00000000000000af
[ 98.349502] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbc327faa7a
[ 98.349503] RDX: 00000000004250c0 RSI: 00000000001b0230 RDI: 00007fbc31919010
[ 98.349505] RBP: 00007fff890df860 R08: 00000000025045b0 R09: 0000000000000000
[ 98.349506] R10: 00000000001b0230 R11: 0000000000000202 R12: 0000000000402410
[ 98.349507] R13: 00007fff890e0cf0 R14: 0000000000000000 R15: 0000000000000000
Thanks
> Thanks
>
>>
>> Fix it by using the devices_rwsem write semaphore to protect the mad_client
>> init flow in enable_device_and_get().
>>
>> Fixes: d0899892edd0 ("RDMA/device: Provide APIs from the core code to help unregistration")
>> Cc: Shifeng Li <lishifeng1992@126.com>
>> Signed-off-by: Shifeng Li <lishifeng@sangfor.com.cn>
>> ---
>> drivers/infiniband/core/device.c | 8 +-------
>> 1 file changed, 1 insertion(+), 7 deletions(-)
>>
>> diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
>> index 67bcea7a153c..85782786993d 100644
>> --- a/drivers/infiniband/core/device.c
>> +++ b/drivers/infiniband/core/device.c
>> @@ -1315,12 +1315,6 @@ static int enable_device_and_get(struct ib_device *device)
>> down_write(&devices_rwsem);
>> xa_set_mark(&devices, device->index, DEVICE_REGISTERED);
>>
>> - /*
>> - * By using downgrade_write() we ensure that no other thread can clear
>> - * DEVICE_REGISTERED while we are completing the client setup.
>> - */
>> - downgrade_write(&devices_rwsem);
>> -
>> if (device->ops.enable_driver) {
>> ret = device->ops.enable_driver(device);
>> if (ret)
>> @@ -1337,7 +1331,7 @@ static int enable_device_and_get(struct ib_device *device)
>> if (!ret)
>> ret = add_compat_devs(device);
>> out:
>> - up_read(&devices_rwsem);
>> + up_write(&devices_rwsem);
>> return ret;
>> }
>>
>> --
>> 2.25.1
>>
>>
>
On Tue, Jan 02, 2024 at 07:33:41PM +0800, Shifeng Li wrote:
> On 2024/1/2 16:58, Leon Romanovsky wrote:
> > On Mon, Jan 01, 2024 at 07:43:35PM -0800, Shifeng Li wrote:
> > > The mad_client will be initialized in enable_device_and_get(), while the
> > > devices_rwsem will be downgraded to a read semaphore. There is a window
> > > that leads to the failed initialization for cm_client, since it can not
> > > get matched mad port from ib_mad_port_list, and the matched mad port will
> > > be added to the list after that.
> > >
> > > mad_client | cm_client
> > > ------------------|--------------------------------------------------------
> > > ib_register_device|
> > > enable_device_and_get
> > > down_write(&devices_rwsem)
> > > xa_set_mark(&devices, DEVICE_REGISTERED)
> > > downgrade_write(&devices_rwsem)
> > > |
> > > |ib_cm_init
> > > |ib_register_client(&cm_client)
> > > |down_read(&devices_rwsem)
> > > |xa_for_each_marked (&devices, DEVICE_REGISTERED)
> > > |add_client_context
> > > |cm_add_one
> > > |ib_register_mad_agent
> > > |ib_get_mad_port
> > > |__ib_get_mad_port
> > > |list_for_each_entry(entry, &ib_mad_port_list, port_list)
> > > |return NULL
> > > |up_read(&devices_rwsem)
> > > |
> > > add_client_context|
> > > ib_mad_init_device|
> > > ib_mad_port_open |
> > > list_add_tail(&port_priv->port_list, &ib_mad_port_list)
> > > up_read(&devices_rwsem)
> > > |
> >
> > How is this stack possible?
> >
> > ib_register_device() is called by drivers and happens much later than ib_cm_init().
> >
>
> I've caught the stack and err log as follows, ib_mad_init_device() called after
ib_mad_init_device != ib_register_device
You mentioned ib_register_device() in your callstack, while you caught ib_mad_init_device().
Thanks
> cm_add_one().
>
> [ 98.281786] CPU: 18 PID: 30079 Comm: modprobe Kdump: loaded
> [ 98.281787] Call Trace:
> [ 98.281790] dump_stack+0x71/0xab
> [ 98.281805] ib_register_mad_agent+0x1c6/0x27f0 [ib_core]
> [ 98.281840] cm_add_one+0x4b0/0x9d0 [ib_cm]
> [ 98.281865] add_client_context+0x2b9/0x380 [ib_core]
> [ 98.281890] ib_register_client+0x22a/0x2a0 [ib_core]
> [ 98.281908] __init_backport+0x12f/0x1000 [ib_cm]
> [ 98.281912] do_one_initcall+0x87/0x2e2
> [ 98.281926] do_init_module+0x1c3/0x5f7
> [ 98.281928] load_module+0x4fe0/0x68d0
> [ 98.281945] __do_sys_finit_module+0x14d/0x180
> [ 98.281952] do_syscall_64+0xa0/0x370
> [ 98.281957] entry_SYSCALL_64_after_hwframe+0x65/0xca
> [ 98.281958] RIP: 0033:0x7f51d3a4373d
> [ 98.281961] RSP: 002b:00007ffceb925938 EFLAGS: 00000202 ORIG_RAX: 0000000000000139
> [ 98.281964] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f51d3a4373d
> [ 98.281965] RDX: 0000000000000000 RSI: 0000000001636b70 RDI: 0000000000000003
> [ 98.281966] RBP: 00007ffceb925950 R08: 0000000000000000 R09: 0000000001636b70
> [ 98.281967] R10: 0000000000000003 R11: 0000000000000202 R12: 0000000000402410
> [ 98.281968] R13: 00007ffceb926e60 R14: 0000000000000000 R15: 0000000000000000
>
> [ 98.281977] infiniband mlx5_1: ib_register_mad_agent: Invalid port 1
>
> [ 98.349040] CPU: 38 PID: 29896 Comm: modprobe Kdump: loaded
> [ 98.349043] Call Trace:
> [ 98.349053] dump_stack+0x71/0xab
> [ 98.349076] ib_register_mad_agent+0x1c6/0x27f0 [ib_core]
> [ 98.349149] ib_agent_port_open+0xe2/0x2d0 [ib_core]
> [ 98.349164] ib_mad_init_device+0x818/0x1d70 [ib_core]
> [ 98.349197] add_client_context+0x2b9/0x380 [ib_core]
> [ 98.349221] enable_device_and_get+0x1ab/0x340 [ib_core]
> [ 98.349292] ib_register_device+0xcbf/0xfd0 [ib_core]
> [ 98.349355] __mlx5_ib_add+0x44/0xf0 [mlx5_ib]
> [ 98.349404] mlx5_add_device+0xc3/0x280 [mlx5_core]
> [ 98.349434] mlx5_register_interface+0x109/0x190 [mlx5_core]
> [ 98.349442] do_one_initcall+0x87/0x2e2
> [ 98.349460] do_init_module+0x1c3/0x5f7
> [ 98.349462] load_module+0x4fe0/0x68d0
> [ 98.349481] __do_sys_init_module+0x1f9/0x220
> [ 98.349486] do_syscall_64+0xa0/0x370
> [ 98.349492] entry_SYSCALL_64_after_hwframe+0x65/0xca
> [ 98.349494] RIP: 0033:0x7fbc327faa7a
> [ 98.349500] RSP: 002b:00007fff890df7f8 EFLAGS: 00000202 ORIG_RAX: 00000000000000af
> [ 98.349502] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbc327faa7a
> [ 98.349503] RDX: 00000000004250c0 RSI: 00000000001b0230 RDI: 00007fbc31919010
> [ 98.349505] RBP: 00007fff890df860 R08: 00000000025045b0 R09: 0000000000000000
> [ 98.349506] R10: 00000000001b0230 R11: 0000000000000202 R12: 0000000000402410
> [ 98.349507] R13: 00007fff890e0cf0 R14: 0000000000000000 R15: 0000000000000000
>
> Thanks
>
> > Thanks
> >
> > >
> > > Fix it by using the devices_rwsem write semaphore to protect the mad_client
> > > init flow in enable_device_and_get().
> > >
> > > Fixes: d0899892edd0 ("RDMA/device: Provide APIs from the core code to help unregistration")
> > > Cc: Shifeng Li <lishifeng1992@126.com>
> > > Signed-off-by: Shifeng Li <lishifeng@sangfor.com.cn>
> > > ---
> > > drivers/infiniband/core/device.c | 8 +-------
> > > 1 file changed, 1 insertion(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
> > > index 67bcea7a153c..85782786993d 100644
> > > --- a/drivers/infiniband/core/device.c
> > > +++ b/drivers/infiniband/core/device.c
> > > @@ -1315,12 +1315,6 @@ static int enable_device_and_get(struct ib_device *device)
> > > down_write(&devices_rwsem);
> > > xa_set_mark(&devices, device->index, DEVICE_REGISTERED);
> > > - /*
> > > - * By using downgrade_write() we ensure that no other thread can clear
> > > - * DEVICE_REGISTERED while we are completing the client setup.
> > > - */
> > > - downgrade_write(&devices_rwsem);
> > > -
> > > if (device->ops.enable_driver) {
> > > ret = device->ops.enable_driver(device);
> > > if (ret)
> > > @@ -1337,7 +1331,7 @@ static int enable_device_and_get(struct ib_device *device)
> > > if (!ret)
> > > ret = add_compat_devs(device);
> > > out:
> > > - up_read(&devices_rwsem);
> > > + up_write(&devices_rwsem);
> > > return ret;
> > > }
> > > --
> > > 2.25.1
> > >
> > >
> >
>
>
On 2024/1/2 19:58, Leon Romanovsky wrote:
> On Tue, Jan 02, 2024 at 07:33:41PM +0800, Shifeng Li wrote:
>> On 2024/1/2 16:58, Leon Romanovsky wrote:
>>> On Mon, Jan 01, 2024 at 07:43:35PM -0800, Shifeng Li wrote:
>>>> The mad_client will be initialized in enable_device_and_get(), while the
>>>> devices_rwsem will be downgraded to a read semaphore. There is a window
>>>> that leads to the failed initialization for cm_client, since it can not
>>>> get matched mad port from ib_mad_port_list, and the matched mad port will
>>>> be added to the list after that.
>>>>
>>>> mad_client | cm_client
>>>> ------------------|--------------------------------------------------------
>>>> ib_register_device|
>>>> enable_device_and_get
>>>> down_write(&devices_rwsem)
>>>> xa_set_mark(&devices, DEVICE_REGISTERED)
>>>> downgrade_write(&devices_rwsem)
>>>> |
>>>> |ib_cm_init
>>>> |ib_register_client(&cm_client)
>>>> |down_read(&devices_rwsem)
>>>> |xa_for_each_marked (&devices, DEVICE_REGISTERED)
>>>> |add_client_context
>>>> |cm_add_one
>>>> |ib_register_mad_agent
>>>> |ib_get_mad_port
>>>> |__ib_get_mad_port
>>>> |list_for_each_entry(entry, &ib_mad_port_list, port_list)
>>>> |return NULL
>>>> |up_read(&devices_rwsem)
>>>> |
>>>> add_client_context|
>>>> ib_mad_init_device|
>>>> ib_mad_port_open |
>>>> list_add_tail(&port_priv->port_list, &ib_mad_port_list)
>>>> up_read(&devices_rwsem)
>>>> |
>>>
>>> How is this stack possible?
>>>
>>> ib_register_device() is called by drivers and happens much later than ib_cm_init().
>>>
>>
>> I've caught the stack and err log as follows, ib_mad_init_device() called after
>
>
> ib_mad_init_device != ib_register_device
>
> You mentioned ib_register_device() in your callstack, while you caught ib_mad_init_device().
>
ib_register_device() is called by mlx5_ib driver, and then ib_register_device()
calls ib_mad_init_device().
Thanks
> Thanks
>
>> cm_add_one().
>>
>> [ 98.281786] CPU: 18 PID: 30079 Comm: modprobe Kdump: loaded
>> [ 98.281787] Call Trace:
>> [ 98.281790] dump_stack+0x71/0xab
>> [ 98.281805] ib_register_mad_agent+0x1c6/0x27f0 [ib_core]
>> [ 98.281840] cm_add_one+0x4b0/0x9d0 [ib_cm]
>> [ 98.281865] add_client_context+0x2b9/0x380 [ib_core]
>> [ 98.281890] ib_register_client+0x22a/0x2a0 [ib_core]
>> [ 98.281908] __init_backport+0x12f/0x1000 [ib_cm]
>> [ 98.281912] do_one_initcall+0x87/0x2e2
>> [ 98.281926] do_init_module+0x1c3/0x5f7
>> [ 98.281928] load_module+0x4fe0/0x68d0
>> [ 98.281945] __do_sys_finit_module+0x14d/0x180
>> [ 98.281952] do_syscall_64+0xa0/0x370
>> [ 98.281957] entry_SYSCALL_64_after_hwframe+0x65/0xca
>> [ 98.281958] RIP: 0033:0x7f51d3a4373d
>> [ 98.281961] RSP: 002b:00007ffceb925938 EFLAGS: 00000202 ORIG_RAX: 0000000000000139
>> [ 98.281964] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f51d3a4373d
>> [ 98.281965] RDX: 0000000000000000 RSI: 0000000001636b70 RDI: 0000000000000003
>> [ 98.281966] RBP: 00007ffceb925950 R08: 0000000000000000 R09: 0000000001636b70
>> [ 98.281967] R10: 0000000000000003 R11: 0000000000000202 R12: 0000000000402410
>> [ 98.281968] R13: 00007ffceb926e60 R14: 0000000000000000 R15: 0000000000000000
>>
>> [ 98.281977] infiniband mlx5_1: ib_register_mad_agent: Invalid port 1
>>
>> [ 98.349040] CPU: 38 PID: 29896 Comm: modprobe Kdump: loaded
>> [ 98.349043] Call Trace:
>> [ 98.349053] dump_stack+0x71/0xab
>> [ 98.349076] ib_register_mad_agent+0x1c6/0x27f0 [ib_core]
>> [ 98.349149] ib_agent_port_open+0xe2/0x2d0 [ib_core]
>> [ 98.349164] ib_mad_init_device+0x818/0x1d70 [ib_core]
>> [ 98.349197] add_client_context+0x2b9/0x380 [ib_core]
>> [ 98.349221] enable_device_and_get+0x1ab/0x340 [ib_core]
>> [ 98.349292] ib_register_device+0xcbf/0xfd0 [ib_core]
>> [ 98.349355] __mlx5_ib_add+0x44/0xf0 [mlx5_ib]
>> [ 98.349404] mlx5_add_device+0xc3/0x280 [mlx5_core]
>> [ 98.349434] mlx5_register_interface+0x109/0x190 [mlx5_core]
>> [ 98.349442] do_one_initcall+0x87/0x2e2
>> [ 98.349460] do_init_module+0x1c3/0x5f7
>> [ 98.349462] load_module+0x4fe0/0x68d0
>> [ 98.349481] __do_sys_init_module+0x1f9/0x220
>> [ 98.349486] do_syscall_64+0xa0/0x370
>> [ 98.349492] entry_SYSCALL_64_after_hwframe+0x65/0xca
>> [ 98.349494] RIP: 0033:0x7fbc327faa7a
>> [ 98.349500] RSP: 002b:00007fff890df7f8 EFLAGS: 00000202 ORIG_RAX: 00000000000000af
>> [ 98.349502] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbc327faa7a
>> [ 98.349503] RDX: 00000000004250c0 RSI: 00000000001b0230 RDI: 00007fbc31919010
>> [ 98.349505] RBP: 00007fff890df860 R08: 00000000025045b0 R09: 0000000000000000
>> [ 98.349506] R10: 00000000001b0230 R11: 0000000000000202 R12: 0000000000402410
>> [ 98.349507] R13: 00007fff890e0cf0 R14: 0000000000000000 R15: 0000000000000000
>>
>> Thanks
>>
>>> Thanks
>>>
>>>>
>>>> Fix it by using the devices_rwsem write semaphore to protect the mad_client
>>>> init flow in enable_device_and_get().
>>>>
>>>> Fixes: d0899892edd0 ("RDMA/device: Provide APIs from the core code to help unregistration")
>>>> Cc: Shifeng Li <lishifeng1992@126.com>
>>>> Signed-off-by: Shifeng Li <lishifeng@sangfor.com.cn>
>>>> ---
>>>> drivers/infiniband/core/device.c | 8 +-------
>>>> 1 file changed, 1 insertion(+), 7 deletions(-)
>>>>
>>>> diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
>>>> index 67bcea7a153c..85782786993d 100644
>>>> --- a/drivers/infiniband/core/device.c
>>>> +++ b/drivers/infiniband/core/device.c
>>>> @@ -1315,12 +1315,6 @@ static int enable_device_and_get(struct ib_device *device)
>>>> down_write(&devices_rwsem);
>>>> xa_set_mark(&devices, device->index, DEVICE_REGISTERED);
>>>> - /*
>>>> - * By using downgrade_write() we ensure that no other thread can clear
>>>> - * DEVICE_REGISTERED while we are completing the client setup.
>>>> - */
>>>> - downgrade_write(&devices_rwsem);
>>>> -
>>>> if (device->ops.enable_driver) {
>>>> ret = device->ops.enable_driver(device);
>>>> if (ret)
>>>> @@ -1337,7 +1331,7 @@ static int enable_device_and_get(struct ib_device *device)
>>>> if (!ret)
>>>> ret = add_compat_devs(device);
>>>> out:
>>>> - up_read(&devices_rwsem);
>>>> + up_write(&devices_rwsem);
>>>> return ret;
>>>> }
>>>> --
>>>> 2.25.1
>>>>
>>>>
>>>
>>
>>
>
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