diff mbox series

[v2,1/6] drm/i915/gem: fix bitwise and logical AND mixup

Message ID 643cc0a4d12f47fd8403d42581e83b1e9c4543c7.1726680898.git.jani.nikula@intel.com (mailing list archive)
State New, archived
Headers show
Series drm/i915: wakeref fixes and improvements | expand

Commit Message

Jani Nikula Sept. 18, 2024, 5:35 p.m. UTC
CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND is an int, defaulting to 250. When
the wakeref is non-zero, it's either -1 or a dynamically allocated
pointer, depending on CONFIG_DRM_I915_DEBUG_RUNTIME_PM. It's likely that
the code works by coincidence with the bitwise AND, but with
CONFIG_DRM_I915_DEBUG_RUNTIME_PM=y, there's the off chance that the
condition evaluates to false, and intel_wakeref_auto() doesn't get
called. Switch to the intended logical AND.

v2: Use != to avoid clang -Wconstant-logical-operand (Nathan)

Fixes: ad74457a6b5a ("drm/i915/dgfx: Release mmap on rpm suspend")
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Anshuman Gupta <anshuman.gupta@intel.com>
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: <stable@vger.kernel.org> # v6.1+
Reviewed-by: Matthew Auld <matthew.auld@intel.com> # v1
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> # v1
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Rodrigo Vivi Sept. 26, 2024, 8:40 p.m. UTC | #1
On Wed, Sep 18, 2024 at 08:35:43PM +0300, Jani Nikula wrote:
> CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND is an int, defaulting to 250. When
> the wakeref is non-zero, it's either -1 or a dynamically allocated
> pointer, depending on CONFIG_DRM_I915_DEBUG_RUNTIME_PM. It's likely that
> the code works by coincidence with the bitwise AND, but with
> CONFIG_DRM_I915_DEBUG_RUNTIME_PM=y, there's the off chance that the
> condition evaluates to false, and intel_wakeref_auto() doesn't get
> called. Switch to the intended logical AND.
> 
> v2: Use != to avoid clang -Wconstant-logical-operand (Nathan)

oh, this is ugly!

Wouldn't it be better then to use IS_ENABLED() macro?

> 
> Fixes: ad74457a6b5a ("drm/i915/dgfx: Release mmap on rpm suspend")
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: Anshuman Gupta <anshuman.gupta@intel.com>
> Cc: Andi Shyti <andi.shyti@linux.intel.com>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: <stable@vger.kernel.org> # v6.1+
> Reviewed-by: Matthew Auld <matthew.auld@intel.com> # v1
> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> # v1
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index 5c72462d1f57..b22e2019768f 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -1131,7 +1131,7 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
>  		GEM_WARN_ON(!i915_ttm_cpu_maps_iomem(bo->resource));
>  	}
>  
> -	if (wakeref & CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND)
> +	if (wakeref && CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND != 0)
>  		intel_wakeref_auto(&to_i915(obj->base.dev)->runtime_pm.userfault_wakeref,
>  				   msecs_to_jiffies_timeout(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND));
>  
> -- 
> 2.39.2
>
Jani Nikula Sept. 27, 2024, 8:38 a.m. UTC | #2
On Thu, 26 Sep 2024, Rodrigo Vivi <rodrigo.vivi@intel.com> wrote:
> On Wed, Sep 18, 2024 at 08:35:43PM +0300, Jani Nikula wrote:
>> CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND is an int, defaulting to 250. When
>> the wakeref is non-zero, it's either -1 or a dynamically allocated
>> pointer, depending on CONFIG_DRM_I915_DEBUG_RUNTIME_PM. It's likely that
>> the code works by coincidence with the bitwise AND, but with
>> CONFIG_DRM_I915_DEBUG_RUNTIME_PM=y, there's the off chance that the
>> condition evaluates to false, and intel_wakeref_auto() doesn't get
>> called. Switch to the intended logical AND.
>> 
>> v2: Use != to avoid clang -Wconstant-logical-operand (Nathan)
>
> oh, this is ugly!
>
> Wouldn't it be better then to use IS_ENABLED() macro?

It's an int config option, not a bool. (Yes, the name is misleading.)

IS_ENABLED(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND) would be the same as
CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND == 1.

We're actually checking if the int value != 0, so IMO the patch at hand
is fine.

BR,
Jani.


>
>> 
>> Fixes: ad74457a6b5a ("drm/i915/dgfx: Release mmap on rpm suspend")
>> Cc: Matthew Auld <matthew.auld@intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>> Cc: Anshuman Gupta <anshuman.gupta@intel.com>
>> Cc: Andi Shyti <andi.shyti@linux.intel.com>
>> Cc: Nathan Chancellor <nathan@kernel.org>
>> Cc: <stable@vger.kernel.org> # v6.1+
>> Reviewed-by: Matthew Auld <matthew.auld@intel.com> # v1
>> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> # v1
>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>> ---
>>  drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>> index 5c72462d1f57..b22e2019768f 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>> @@ -1131,7 +1131,7 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
>>  		GEM_WARN_ON(!i915_ttm_cpu_maps_iomem(bo->resource));
>>  	}
>>  
>> -	if (wakeref & CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND)
>> +	if (wakeref && CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND != 0)
>>  		intel_wakeref_auto(&to_i915(obj->base.dev)->runtime_pm.userfault_wakeref,
>>  				   msecs_to_jiffies_timeout(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND));
>>  
>> -- 
>> 2.39.2
>>
Jani Nikula Sept. 30, 2024, 1:54 p.m. UTC | #3
On Fri, 27 Sep 2024, Jani Nikula <jani.nikula@intel.com> wrote:
> On Thu, 26 Sep 2024, Rodrigo Vivi <rodrigo.vivi@intel.com> wrote:
>> On Wed, Sep 18, 2024 at 08:35:43PM +0300, Jani Nikula wrote:
>>> CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND is an int, defaulting to 250. When
>>> the wakeref is non-zero, it's either -1 or a dynamically allocated
>>> pointer, depending on CONFIG_DRM_I915_DEBUG_RUNTIME_PM. It's likely that
>>> the code works by coincidence with the bitwise AND, but with
>>> CONFIG_DRM_I915_DEBUG_RUNTIME_PM=y, there's the off chance that the
>>> condition evaluates to false, and intel_wakeref_auto() doesn't get
>>> called. Switch to the intended logical AND.
>>> 
>>> v2: Use != to avoid clang -Wconstant-logical-operand (Nathan)
>>
>> oh, this is ugly!
>>
>> Wouldn't it be better then to use IS_ENABLED() macro?
>
> It's an int config option, not a bool. (Yes, the name is misleading.)
>
> IS_ENABLED(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND) would be the same as
> CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND == 1.
>
> We're actually checking if the int value != 0, so IMO the patch at hand
> is fine.

Ping, r-b on this one too?

BR,
Jani.

>
> BR,
> Jani.
>
>
>>
>>> 
>>> Fixes: ad74457a6b5a ("drm/i915/dgfx: Release mmap on rpm suspend")
>>> Cc: Matthew Auld <matthew.auld@intel.com>
>>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>>> Cc: Anshuman Gupta <anshuman.gupta@intel.com>
>>> Cc: Andi Shyti <andi.shyti@linux.intel.com>
>>> Cc: Nathan Chancellor <nathan@kernel.org>
>>> Cc: <stable@vger.kernel.org> # v6.1+
>>> Reviewed-by: Matthew Auld <matthew.auld@intel.com> # v1
>>> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> # v1
>>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>>> ---
>>>  drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>> 
>>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>>> index 5c72462d1f57..b22e2019768f 100644
>>> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>>> @@ -1131,7 +1131,7 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
>>>  		GEM_WARN_ON(!i915_ttm_cpu_maps_iomem(bo->resource));
>>>  	}
>>>  
>>> -	if (wakeref & CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND)
>>> +	if (wakeref && CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND != 0)
>>>  		intel_wakeref_auto(&to_i915(obj->base.dev)->runtime_pm.userfault_wakeref,
>>>  				   msecs_to_jiffies_timeout(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND));
>>>  
>>> -- 
>>> 2.39.2
>>>
Matthew Auld Sept. 30, 2024, 2:23 p.m. UTC | #4
On 30/09/2024 14:54, Jani Nikula wrote:
> On Fri, 27 Sep 2024, Jani Nikula <jani.nikula@intel.com> wrote:
>> On Thu, 26 Sep 2024, Rodrigo Vivi <rodrigo.vivi@intel.com> wrote:
>>> On Wed, Sep 18, 2024 at 08:35:43PM +0300, Jani Nikula wrote:
>>>> CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND is an int, defaulting to 250. When
>>>> the wakeref is non-zero, it's either -1 or a dynamically allocated
>>>> pointer, depending on CONFIG_DRM_I915_DEBUG_RUNTIME_PM. It's likely that
>>>> the code works by coincidence with the bitwise AND, but with
>>>> CONFIG_DRM_I915_DEBUG_RUNTIME_PM=y, there's the off chance that the
>>>> condition evaluates to false, and intel_wakeref_auto() doesn't get
>>>> called. Switch to the intended logical AND.
>>>>
>>>> v2: Use != to avoid clang -Wconstant-logical-operand (Nathan)
>>>
>>> oh, this is ugly!
>>>
>>> Wouldn't it be better then to use IS_ENABLED() macro?
>>
>> It's an int config option, not a bool. (Yes, the name is misleading.)
>>
>> IS_ENABLED(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND) would be the same as
>> CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND == 1.
>>
>> We're actually checking if the int value != 0, so IMO the patch at hand
>> is fine.
> 
> Ping, r-b on this one too?

r-b still holds for v2, fwiw.

> 
> BR,
> Jani.
> 
>>
>> BR,
>> Jani.
>>
>>
>>>
>>>>
>>>> Fixes: ad74457a6b5a ("drm/i915/dgfx: Release mmap on rpm suspend")
>>>> Cc: Matthew Auld <matthew.auld@intel.com>
>>>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>>>> Cc: Anshuman Gupta <anshuman.gupta@intel.com>
>>>> Cc: Andi Shyti <andi.shyti@linux.intel.com>
>>>> Cc: Nathan Chancellor <nathan@kernel.org>
>>>> Cc: <stable@vger.kernel.org> # v6.1+
>>>> Reviewed-by: Matthew Auld <matthew.auld@intel.com> # v1
>>>> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> # v1
>>>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>>>> ---
>>>>   drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 2 +-
>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>>>> index 5c72462d1f57..b22e2019768f 100644
>>>> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>>>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>>>> @@ -1131,7 +1131,7 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
>>>>   		GEM_WARN_ON(!i915_ttm_cpu_maps_iomem(bo->resource));
>>>>   	}
>>>>   
>>>> -	if (wakeref & CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND)
>>>> +	if (wakeref && CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND != 0)
>>>>   		intel_wakeref_auto(&to_i915(obj->base.dev)->runtime_pm.userfault_wakeref,
>>>>   				   msecs_to_jiffies_timeout(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND));
>>>>   
>>>> -- 
>>>> 2.39.2
>>>>
>
Jani Nikula Sept. 30, 2024, 2:58 p.m. UTC | #5
On Mon, 30 Sep 2024, Matthew Auld <matthew.auld@intel.com> wrote:
> On 30/09/2024 14:54, Jani Nikula wrote:
>> On Fri, 27 Sep 2024, Jani Nikula <jani.nikula@intel.com> wrote:
>>> On Thu, 26 Sep 2024, Rodrigo Vivi <rodrigo.vivi@intel.com> wrote:
>>>> On Wed, Sep 18, 2024 at 08:35:43PM +0300, Jani Nikula wrote:
>>>>> CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND is an int, defaulting to 250. When
>>>>> the wakeref is non-zero, it's either -1 or a dynamically allocated
>>>>> pointer, depending on CONFIG_DRM_I915_DEBUG_RUNTIME_PM. It's likely that
>>>>> the code works by coincidence with the bitwise AND, but with
>>>>> CONFIG_DRM_I915_DEBUG_RUNTIME_PM=y, there's the off chance that the
>>>>> condition evaluates to false, and intel_wakeref_auto() doesn't get
>>>>> called. Switch to the intended logical AND.
>>>>>
>>>>> v2: Use != to avoid clang -Wconstant-logical-operand (Nathan)
>>>>
>>>> oh, this is ugly!
>>>>
>>>> Wouldn't it be better then to use IS_ENABLED() macro?
>>>
>>> It's an int config option, not a bool. (Yes, the name is misleading.)
>>>
>>> IS_ENABLED(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND) would be the same as
>>> CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND == 1.
>>>
>>> We're actually checking if the int value != 0, so IMO the patch at hand
>>> is fine.
>> 
>> Ping, r-b on this one too?
>
> r-b still holds for v2, fwiw.

Thanks for the reviews, pushed the lot to drm-intel-next.

BR,
Jani.

>
>> 
>> BR,
>> Jani.
>> 
>>>
>>> BR,
>>> Jani.
>>>
>>>
>>>>
>>>>>
>>>>> Fixes: ad74457a6b5a ("drm/i915/dgfx: Release mmap on rpm suspend")
>>>>> Cc: Matthew Auld <matthew.auld@intel.com>
>>>>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>>>>> Cc: Anshuman Gupta <anshuman.gupta@intel.com>
>>>>> Cc: Andi Shyti <andi.shyti@linux.intel.com>
>>>>> Cc: Nathan Chancellor <nathan@kernel.org>
>>>>> Cc: <stable@vger.kernel.org> # v6.1+
>>>>> Reviewed-by: Matthew Auld <matthew.auld@intel.com> # v1
>>>>> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> # v1
>>>>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>>>>> ---
>>>>>   drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 2 +-
>>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>>>>> index 5c72462d1f57..b22e2019768f 100644
>>>>> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>>>>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
>>>>> @@ -1131,7 +1131,7 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
>>>>>   		GEM_WARN_ON(!i915_ttm_cpu_maps_iomem(bo->resource));
>>>>>   	}
>>>>>   
>>>>> -	if (wakeref & CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND)
>>>>> +	if (wakeref && CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND != 0)
>>>>>   		intel_wakeref_auto(&to_i915(obj->base.dev)->runtime_pm.userfault_wakeref,
>>>>>   				   msecs_to_jiffies_timeout(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND));
>>>>>   
>>>>> -- 
>>>>> 2.39.2
>>>>>
>>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index 5c72462d1f57..b22e2019768f 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -1131,7 +1131,7 @@  static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
 		GEM_WARN_ON(!i915_ttm_cpu_maps_iomem(bo->resource));
 	}
 
-	if (wakeref & CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND)
+	if (wakeref && CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND != 0)
 		intel_wakeref_auto(&to_i915(obj->base.dev)->runtime_pm.userfault_wakeref,
 				   msecs_to_jiffies_timeout(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND));