linux-kernel - Re: [PATCH 1/3] amdkfd: Don't clear *kfd2kgd on kfd_module

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Date:	Sun, 21 Dec 2014 12:27:41 +0100
From:	Christian König <deathsimple@...afone.de>
To:	Oded Gabbay <oded.gabbay@....com>, dri-devel@...ts.freedesktop.org
CC:	linux-kernel@...r.kernel.org, Alexander.Deucher@....com
Subject: Re: [PATCH 1/3] amdkfd: Don't clear *kfd2kgd on kfd_module_init

Am 20.12.2014 um 21:46 schrieb Oded Gabbay:
> When amdkfd and radeon are compiled inside the kernel image (not as modules),
> radeon will load before amdkfd and will set *kfd2kgd to its interface
> structure. Therefore, we must not set *kfd2kgd to NULL when amdkfd is loaded
> because it will override radeon's initialization and cause kernel BUG.
>
> Signed-off-by: Oded Gabbay <oded.gabbay@....com>

You should probably rather fix the dependency between the two modules to 
get an determined load order instead of doing such nasty workarounds.

Christian.

> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_module.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_module.c b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
> index 95d5af1..236562f 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_module.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
> @@ -34,7 +34,7 @@
>   #define KFD_DRIVER_MINOR	7
>   #define KFD_DRIVER_PATCHLEVEL	0
>   
> -const struct kfd2kgd_calls *kfd2kgd;
> +const struct kfd2kgd_calls *kfd2kgd = NULL;
>   static const struct kgd2kfd_calls kgd2kfd = {
>   	.exit		= kgd2kfd_exit,
>   	.probe		= kgd2kfd_probe,
> @@ -84,14 +84,13 @@ EXPORT_SYMBOL(kgd2kfd_init);
>   
>   void kgd2kfd_exit(void)
>   {
> +	kfd2kgd = NULL;
>   }
>   
>   static int __init kfd_module_init(void)
>   {
>   	int err;
>   
> -	kfd2kgd = NULL;
> -
>   	/* Verify module parameters */
>   	if ((sched_policy < KFD_SCHED_POLICY_HWS) ||
>   		(sched_policy > KFD_SCHED_POLICY_NO_HWS)) {

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