Re: [PATCH 2/2] drm/xe/hwmon: Fix static analysis tool reported issues

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 21 Mar 2024, Karthik Poosa <karthik.poosa@intel.com> wrote:
> Update xe hwmon with fixes for issues reported by static analysis
> tool.
> Fix integer overflow with upcasting.
> Initialize uninitialized variables.
>
> Fixes: 4446fcf220ce ("drm/xe/hwmon: Expose power1_max_interval")
> Signed-off-by: Karthik Poosa <karthik.poosa@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_hwmon.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_hwmon.c b/drivers/gpu/drm/xe/xe_hwmon.c
> index a256af8c2012..6ed9d5c4f6b1 100644
> --- a/drivers/gpu/drm/xe/xe_hwmon.c
> +++ b/drivers/gpu/drm/xe/xe_hwmon.c
> @@ -153,7 +153,7 @@ static void xe_hwmon_process_reg(struct xe_hwmon *hwmon, enum xe_hwmon_reg hwmon
>   */
>  static void xe_hwmon_power_max_read(struct xe_hwmon *hwmon, long *value)
>  {
> -	u64 reg_val, min, max;
> +	u64 reg_val = 0, min, max;

Nah. Just fix xe_hwmon_process_reg() to set *value = 0.

Side note, xe_hwmon_get_reg() should return struct xe_reg instead of
u32, and xe_hwmon_process_reg() has no business looking into the guts of
struct xe_reg.


BR,
Jani.


>  
>  	mutex_lock(&hwmon->hwmon_lock);
>  
> @@ -182,7 +182,7 @@ static void xe_hwmon_power_max_read(struct xe_hwmon *hwmon, long *value)
>  static int xe_hwmon_power_max_write(struct xe_hwmon *hwmon, long value)
>  {
>  	int ret = 0;
> -	u64 reg_val;
> +	u64 reg_val = 0;
>  
>  	mutex_lock(&hwmon->hwmon_lock);
>  
> @@ -212,7 +212,7 @@ static int xe_hwmon_power_max_write(struct xe_hwmon *hwmon, long value)
>  
>  static void xe_hwmon_power_rated_max_read(struct xe_hwmon *hwmon, long *value)
>  {
> -	u64 reg_val;
> +	u64 reg_val = 0;
>  
>  	xe_hwmon_process_reg(hwmon, REG_PKG_POWER_SKU, REG_READ32, &reg_val, 0, 0);
>  	reg_val = REG_FIELD_GET(PKG_TDP, reg_val);
> @@ -243,7 +243,7 @@ static void
>  xe_hwmon_energy_get(struct xe_hwmon *hwmon, long *energy)
>  {
>  	struct xe_hwmon_energy_info *ei = &hwmon->ei;
> -	u64 reg_val;
> +	u64 reg_val = 0;
>  
>  	xe_hwmon_process_reg(hwmon, REG_PKG_ENERGY_STATUS, REG_READ32,
>  			     &reg_val, 0, 0);
> @@ -264,8 +264,8 @@ xe_hwmon_power1_max_interval_show(struct device *dev, struct device_attribute *a
>  				  char *buf)
>  {
>  	struct xe_hwmon *hwmon = dev_get_drvdata(dev);
> -	u32 x, y, x_w = 2; /* 2 bits */
> -	u64 r, tau4, out;
> +	u32 x = 0, y = 0, x_w = 2; /* 2 bits */
> +	u64 r = 0, tau4, out;
>  
>  	xe_pm_runtime_get(gt_to_xe(hwmon->gt));
>  
> @@ -291,7 +291,7 @@ xe_hwmon_power1_max_interval_show(struct device *dev, struct device_attribute *a
>  	 * As y can be < 2, we compute tau4 = (4 | x) << y
>  	 * and then add 2 when doing the final right shift to account for units
>  	 */
> -	tau4 = ((1 << x_w) | x) << y;
> +	tau4 = (u64)((1 << x_w) | x) << y;
>  
>  	/* val in hwmon interface units (millisec) */
>  	out = mul_u64_u32_shr(tau4, SF_TIME, hwmon->scl_shift_time + x_w);
> @@ -331,7 +331,7 @@ xe_hwmon_power1_max_interval_store(struct device *dev, struct device_attribute *
>  	r = FIELD_PREP(PKG_MAX_WIN, PKG_MAX_WIN_DEFAULT);
>  	x = REG_FIELD_GET(PKG_MAX_WIN_X, r);
>  	y = REG_FIELD_GET(PKG_MAX_WIN_Y, r);
> -	tau4 = ((1 << x_w) | x) << y;
> +	tau4 = (u64)((1 << x_w) | x) << y;
>  	max_win = mul_u64_u32_shr(tau4, SF_TIME, hwmon->scl_shift_time + x_w);
>  
>  	if (val > max_win)
> @@ -466,7 +466,7 @@ static int xe_hwmon_power_curr_crit_write(struct xe_hwmon *hwmon, long value, u3
>  
>  static void xe_hwmon_get_voltage(struct xe_hwmon *hwmon, long *value)
>  {
> -	u64 reg_val;
> +	u64 reg_val = 0;
>  
>  	xe_hwmon_process_reg(hwmon, REG_GT_PERF_STATUS,
>  			     REG_READ32, &reg_val, 0, 0);

-- 
Jani Nikula, Intel