linux-kernel - Re: [PATCH] drm/radeon/ci_dpm: Remove needless NULL checks of dpm tables

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Message-ID: <6a817784-f3d4-43c2-bd94-ac40c73e8583@fintech.ru>
Date: Thu, 13 Feb 2025 20:03:32 +0300
From: Nikita Zhandarovich <n.zhandarovich@...tech.ru>
To: Alex Deucher <alexander.deucher@....com>, Christian König
	<christian.koenig@....com>
CC: Xinhui Pan <Xinhui.Pan@....com>, David Airlie <airlied@...il.com>,
	"Simona Vetter" <simona@...ll.ch>, <amd-gfx@...ts.freedesktop.org>,
	<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
	<lvc-project@...uxtesting.org>
Subject: Re: [PATCH] drm/radeon/ci_dpm: Remove needless NULL checks of dpm
 tables

Gentle ping :)

On 1/14/25 16:58, Nikita Zhandarovich wrote:
> This patch removes useless NULL pointer checks in functions like
> ci_set_private_data_variables_based_on_pptable() and
> ci_setup_default_dpm_tables().
> 
> The pointers in question are initialized as addresses to existing
> structures such as rdev->pm.dpm.dyn_state.vddc_dependency_on_sclk by
> utilizing & operator and therefore are not in danger of being NULL.
> 
> Fix this by removing extra checks thus cleaning the code a tiny bit.
> 
> Found by Linux Verification Center (linuxtesting.org) with static
> analysis tool SVACE.
> 
> Fixes: cc8dbbb4f62a ("drm/radeon: add dpm support for CI dGPUs (v2)")
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@...tech.ru>
> ---
>  drivers/gpu/drm/radeon/ci_dpm.c | 34 ++++++++++------------------------
>  1 file changed, 10 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/gpu/drm/radeon/ci_dpm.c b/drivers/gpu/drm/radeon/ci_dpm.c
> index abe9d65cc460..7c3a960f486a 100644
> --- a/drivers/gpu/drm/radeon/ci_dpm.c
> +++ b/drivers/gpu/drm/radeon/ci_dpm.c
> @@ -3405,12 +3405,8 @@ static int ci_setup_default_dpm_tables(struct radeon_device *rdev)
>  		&rdev->pm.dpm.dyn_state.cac_leakage_table;
>  	u32 i;
>  
> -	if (allowed_sclk_vddc_table == NULL)
> -		return -EINVAL;
>  	if (allowed_sclk_vddc_table->count < 1)
>  		return -EINVAL;
> -	if (allowed_mclk_table == NULL)
> -		return -EINVAL;
>  	if (allowed_mclk_table->count < 1)
>  		return -EINVAL;
>  
> @@ -3468,24 +3464,20 @@ static int ci_setup_default_dpm_tables(struct radeon_device *rdev)
>  	pi->dpm_table.vddc_table.count = allowed_sclk_vddc_table->count;
>  
>  	allowed_mclk_table = &rdev->pm.dpm.dyn_state.vddci_dependency_on_mclk;
> -	if (allowed_mclk_table) {
> -		for (i = 0; i < allowed_mclk_table->count; i++) {
> -			pi->dpm_table.vddci_table.dpm_levels[i].value =
> -				allowed_mclk_table->entries[i].v;
> -			pi->dpm_table.vddci_table.dpm_levels[i].enabled = true;
> -		}
> -		pi->dpm_table.vddci_table.count = allowed_mclk_table->count;
> +	for (i = 0; i < allowed_mclk_table->count; i++) {
> +		pi->dpm_table.vddci_table.dpm_levels[i].value =
> +			allowed_mclk_table->entries[i].v;
> +		pi->dpm_table.vddci_table.dpm_levels[i].enabled = true;
>  	}
> +	pi->dpm_table.vddci_table.count = allowed_mclk_table->count;
>  
>  	allowed_mclk_table = &rdev->pm.dpm.dyn_state.mvdd_dependency_on_mclk;
> -	if (allowed_mclk_table) {
> -		for (i = 0; i < allowed_mclk_table->count; i++) {
> -			pi->dpm_table.mvdd_table.dpm_levels[i].value =
> -				allowed_mclk_table->entries[i].v;
> -			pi->dpm_table.mvdd_table.dpm_levels[i].enabled = true;
> -		}
> -		pi->dpm_table.mvdd_table.count = allowed_mclk_table->count;
> +	for (i = 0; i < allowed_mclk_table->count; i++) {
> +		pi->dpm_table.mvdd_table.dpm_levels[i].value =
> +			allowed_mclk_table->entries[i].v;
> +		pi->dpm_table.mvdd_table.dpm_levels[i].enabled = true;
>  	}
> +	pi->dpm_table.mvdd_table.count = allowed_mclk_table->count;
>  
>  	ci_setup_default_pcie_tables(rdev);
>  
> @@ -4880,16 +4872,10 @@ static int ci_set_private_data_variables_based_on_pptable(struct radeon_device *
>  	struct radeon_clock_voltage_dependency_table *allowed_mclk_vddci_table =
>  		&rdev->pm.dpm.dyn_state.vddci_dependency_on_mclk;
>  
> -	if (allowed_sclk_vddc_table == NULL)
> -		return -EINVAL;
>  	if (allowed_sclk_vddc_table->count < 1)
>  		return -EINVAL;
> -	if (allowed_mclk_vddc_table == NULL)
> -		return -EINVAL;
>  	if (allowed_mclk_vddc_table->count < 1)
>  		return -EINVAL;
> -	if (allowed_mclk_vddci_table == NULL)
> -		return -EINVAL;
>  	if (allowed_mclk_vddci_table->count < 1)
>  		return -EINVAL;
>