[PATCH] rpmsg: glink: fix deadlock in endpoint destroy during driver detach

[PATCH] rpmsg: glink: fix deadlock in endpoint destroy during driver detach

[Vishnu Santhosh]

During driver detach, the device core holds the device mutex throughout
the driver's remove callback chain.  When the rpmsg endpoint is
destroyed as part of that teardown, the GLINK endpoint destroy
implementation attempts to unregister the underlying rpmsg device.
That unregistration calls device_del(), which tries to re-acquire the
same device mutex already held higher up the stack, causing rmmod to
hang indefinitely.

The deadlock manifests with the following call chain:

[<0>] device_del+0x44/0x414  <- tries to acquire same mutex
[<0>] device_unregister+0x18/0x34
[<0>] rpmsg_unregister_device+0x28/0x4c
[<0>] qcom_glink_remove_rpmsg_device+0x70/0xc0
[<0>] qcom_glink_destroy_ept+0x58/0xbc
[<0>] rpmsg_dev_remove+0x50/0x60
[<0>] device_remove+0x4c/0x80
[<0>] device_release_driver_internal+0x1cc/0x228  <- acquires device mutex
[<0>] driver_detach+0x4c/0x98
[<0>] bus_remove_driver+0x6c/0xbc
[<0>] driver_unregister+0x30/0x60
[<0>] unregister_rpmsg_driver+0x10/0x1c
[<0>] fastrpc_exit+0x28/0x38 [fastrpc]
[<0>] __arm64_sys_delete_module+0x1b8/0x294
[<0>] invoke_syscall+0x48/0x10c
[<0>] el0_svc_common.constprop.0+0xc0/0xe0
[<0>] do_el0_svc+0x1c/0x28
[<0>] el0_svc+0x34/0x108
[<0>] el0t_64_sync_handler+0xa0/0xe4
[<0>] el0t_64_sync+0x198/0x19c

The rpmsg device unregistration inside endpoint destroy is redundant.
In both contexts where endpoint destruction is triggered:

- Driver detach path: the driver core already tears down the rpmsg
  device.

- Channel close path: the rpmsg device is already unregistered before
  endpoint destruction is reached.

Remove the redundant unregistration to fix the deadlock.

Co-developed-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
Signed-off-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
Signed-off-by: Vishnu Santhosh <vishnu.santhosh@oss.qualcomm.com>
---
 drivers/rpmsg/qcom_glink_native.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
index 401a4ece0c9777398837d4427746fae0a5003e88..ab7ff3d2f56bf797592fc4227ce5b730bce72226 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c
@@ -1418,9 +1418,6 @@ static void qcom_glink_destroy_ept(struct rpmsg_endpoint *ept)
 	channel->ept.cb = NULL;
 	spin_unlock_irqrestore(&channel->recv_lock, flags);
 
-	/* Decouple the potential rpdev from the channel */
-	qcom_glink_remove_rpmsg_device(glink, channel);
-
 	qcom_glink_send_close_req(glink, channel);
 }
 

---
base-commit: ba3e43a9e601636f5edb54e259a74f96ca3b8fd8
change-id: 20260416-rpmsg-glink-fix-deadlock-destroy-ept-5cc7aac522a0

Best regards,
-- 
Vishnu Santhosh <vishnu.santhosh@oss.qualcomm.com>

Re: [PATCH] rpmsg: glink: fix deadlock in endpoint destroy during driver detach

[Jie Gan]

On 6/4/2026 4:42 PM, Vishnu Santhosh wrote:
> During driver detach, the device core holds the device mutex throughout
> the driver's remove callback chain.  When the rpmsg endpoint is
> destroyed as part of that teardown, the GLINK endpoint destroy
> implementation attempts to unregister the underlying rpmsg device.
> That unregistration calls device_del(), which tries to re-acquire the
> same device mutex already held higher up the stack, causing rmmod to
> hang indefinitely.
> 
> The deadlock manifests with the following call chain:
> 
> [<0>] device_del+0x44/0x414  <- tries to acquire same mutex
> [<0>] device_unregister+0x18/0x34
> [<0>] rpmsg_unregister_device+0x28/0x4c
> [<0>] qcom_glink_remove_rpmsg_device+0x70/0xc0
> [<0>] qcom_glink_destroy_ept+0x58/0xbc
> [<0>] rpmsg_dev_remove+0x50/0x60
> [<0>] device_remove+0x4c/0x80
> [<0>] device_release_driver_internal+0x1cc/0x228  <- acquires device mutex
> [<0>] driver_detach+0x4c/0x98
> [<0>] bus_remove_driver+0x6c/0xbc
> [<0>] driver_unregister+0x30/0x60
> [<0>] unregister_rpmsg_driver+0x10/0x1c
> [<0>] fastrpc_exit+0x28/0x38 [fastrpc]
> [<0>] __arm64_sys_delete_module+0x1b8/0x294
> [<0>] invoke_syscall+0x48/0x10c
> [<0>] el0_svc_common.constprop.0+0xc0/0xe0
> [<0>] do_el0_svc+0x1c/0x28
> [<0>] el0_svc+0x34/0x108
> [<0>] el0t_64_sync_handler+0xa0/0xe4
> [<0>] el0t_64_sync+0x198/0x19c
> 
> The rpmsg device unregistration inside endpoint destroy is redundant.
> In both contexts where endpoint destruction is triggered:
> 
> - Driver detach path: the driver core already tears down the rpmsg
>    device.
> 
> - Channel close path: the rpmsg device is already unregistered before
>    endpoint destruction is reached.
> 
> Remove the redundant unregistration to fix the deadlock.
> 

Fixes: a53e356df548 ("rpmsg: glink: fix rpmsg device leak")

Thanks,
Jie

> Co-developed-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
> Signed-off-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
> Signed-off-by: Vishnu Santhosh <vishnu.santhosh@oss.qualcomm.com>
> ---
>   drivers/rpmsg/qcom_glink_native.c | 3 ---
>   1 file changed, 3 deletions(-)
> 
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index 401a4ece0c9777398837d4427746fae0a5003e88..ab7ff3d2f56bf797592fc4227ce5b730bce72226 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -1418,9 +1418,6 @@ static void qcom_glink_destroy_ept(struct rpmsg_endpoint *ept)
>   	channel->ept.cb = NULL;
>   	spin_unlock_irqrestore(&channel->recv_lock, flags);
>   
> -	/* Decouple the potential rpdev from the channel */
> -	qcom_glink_remove_rpmsg_device(glink, channel);
> -
>   	qcom_glink_send_close_req(glink, channel);
>   }
>   
> 
> ---
> base-commit: ba3e43a9e601636f5edb54e259a74f96ca3b8fd8
> change-id: 20260416-rpmsg-glink-fix-deadlock-destroy-ept-5cc7aac522a0
> 
> Best regards,

Re: [PATCH] rpmsg: glink: fix deadlock in endpoint destroy during driver detach

[Dmitry Baryshkov]

On Fri, Jun 05, 2026 at 09:17:19AM +0800, Jie Gan wrote:
> 
> 
> On 6/4/2026 4:42 PM, Vishnu Santhosh wrote:
> > During driver detach, the device core holds the device mutex throughout
> > the driver's remove callback chain.  When the rpmsg endpoint is
> > destroyed as part of that teardown, the GLINK endpoint destroy
> > implementation attempts to unregister the underlying rpmsg device.
> > That unregistration calls device_del(), which tries to re-acquire the
> > same device mutex already held higher up the stack, causing rmmod to
> > hang indefinitely.
> > 
> > The deadlock manifests with the following call chain:
> > 
> > [<0>] device_del+0x44/0x414  <- tries to acquire same mutex
> > [<0>] device_unregister+0x18/0x34
> > [<0>] rpmsg_unregister_device+0x28/0x4c
> > [<0>] qcom_glink_remove_rpmsg_device+0x70/0xc0
> > [<0>] qcom_glink_destroy_ept+0x58/0xbc
> > [<0>] rpmsg_dev_remove+0x50/0x60
> > [<0>] device_remove+0x4c/0x80
> > [<0>] device_release_driver_internal+0x1cc/0x228  <- acquires device mutex
> > [<0>] driver_detach+0x4c/0x98
> > [<0>] bus_remove_driver+0x6c/0xbc
> > [<0>] driver_unregister+0x30/0x60
> > [<0>] unregister_rpmsg_driver+0x10/0x1c
> > [<0>] fastrpc_exit+0x28/0x38 [fastrpc]
> > [<0>] __arm64_sys_delete_module+0x1b8/0x294
> > [<0>] invoke_syscall+0x48/0x10c
> > [<0>] el0_svc_common.constprop.0+0xc0/0xe0
> > [<0>] do_el0_svc+0x1c/0x28
> > [<0>] el0_svc+0x34/0x108
> > [<0>] el0t_64_sync_handler+0xa0/0xe4
> > [<0>] el0t_64_sync+0x198/0x19c
> > 
> > The rpmsg device unregistration inside endpoint destroy is redundant.
> > In both contexts where endpoint destruction is triggered:
> > 
> > - Driver detach path: the driver core already tears down the rpmsg
> >    device.
> > 
> > - Channel close path: the rpmsg device is already unregistered before
> >    endpoint destruction is reached.
> > 
> > Remove the redundant unregistration to fix the deadlock.
> > 
> 
> Fixes: a53e356df548 ("rpmsg: glink: fix rpmsg device leak")
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>


-- 
With best wishes
Dmitry

Re: [PATCH] rpmsg: glink: fix deadlock in endpoint destroy during driver detach

[Bjorn Andersson]

On Thu, Jun 04, 2026 at 02:12:53PM +0530, Vishnu Santhosh wrote:
> During driver detach, the device core holds the device mutex throughout
> the driver's remove callback chain.  When the rpmsg endpoint is
> destroyed as part of that teardown, the GLINK endpoint destroy
> implementation attempts to unregister the underlying rpmsg device.
> That unregistration calls device_del(), which tries to re-acquire the
> same device mutex already held higher up the stack, causing rmmod to
> hang indefinitely.
> 
> The deadlock manifests with the following call chain:
> 
> [<0>] device_del+0x44/0x414  <- tries to acquire same mutex
> [<0>] device_unregister+0x18/0x34
> [<0>] rpmsg_unregister_device+0x28/0x4c
> [<0>] qcom_glink_remove_rpmsg_device+0x70/0xc0
> [<0>] qcom_glink_destroy_ept+0x58/0xbc
> [<0>] rpmsg_dev_remove+0x50/0x60
> [<0>] device_remove+0x4c/0x80
> [<0>] device_release_driver_internal+0x1cc/0x228  <- acquires device mutex
> [<0>] driver_detach+0x4c/0x98
> [<0>] bus_remove_driver+0x6c/0xbc
> [<0>] driver_unregister+0x30/0x60
> [<0>] unregister_rpmsg_driver+0x10/0x1c
> [<0>] fastrpc_exit+0x28/0x38 [fastrpc]
> [<0>] __arm64_sys_delete_module+0x1b8/0x294
> [<0>] invoke_syscall+0x48/0x10c
> [<0>] el0_svc_common.constprop.0+0xc0/0xe0
> [<0>] do_el0_svc+0x1c/0x28
> [<0>] el0_svc+0x34/0x108
> [<0>] el0t_64_sync_handler+0xa0/0xe4
> [<0>] el0t_64_sync+0x198/0x19c
> 
> The rpmsg device unregistration inside endpoint destroy is redundant.
> In both contexts where endpoint destruction is triggered:
> 
> - Driver detach path: the driver core already tears down the rpmsg
>   device.
> 
> - Channel close path: the rpmsg device is already unregistered before
>   endpoint destruction is reached.
> 
> Remove the redundant unregistration to fix the deadlock.
> 
> Co-developed-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
> Signed-off-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
> Signed-off-by: Vishnu Santhosh <vishnu.santhosh@oss.qualcomm.com>

Tested-by: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>

Regards,
Bjorn

> ---
>  drivers/rpmsg/qcom_glink_native.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index 401a4ece0c9777398837d4427746fae0a5003e88..ab7ff3d2f56bf797592fc4227ce5b730bce72226 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -1418,9 +1418,6 @@ static void qcom_glink_destroy_ept(struct rpmsg_endpoint *ept)
>  	channel->ept.cb = NULL;
>  	spin_unlock_irqrestore(&channel->recv_lock, flags);
>  
> -	/* Decouple the potential rpdev from the channel */
> -	qcom_glink_remove_rpmsg_device(glink, channel);
> -
>  	qcom_glink_send_close_req(glink, channel);
>  }
>  
> 
> ---
> base-commit: ba3e43a9e601636f5edb54e259a74f96ca3b8fd8
> change-id: 20260416-rpmsg-glink-fix-deadlock-destroy-ept-5cc7aac522a0
> 
> Best regards,
> -- 
> Vishnu Santhosh <vishnu.santhosh@oss.qualcomm.com>
>