re: drm/amd/powerplay: add dpm force multiple levels on cz/tonga/fiji/polaris (v2)

From: Dan Carpenter <dan.carpenter@oracle.com>
To: JinHuiEric.Huang@amd.com
Cc: dri-devel@lists.freedesktop.org
Subject: re: drm/amd/powerplay: add dpm force multiple levels on cz/tonga/fiji/polaris (v2)
Date: Tue, 10 May 2016 13:51:21 +0300	[thread overview]
Message-ID: <20160510105121.GA11874@mwanda> (raw)

Hello Eric Huang,

The patch 5632708f4452: "drm/amd/powerplay: add dpm force multiple
levels on cz/tonga/fiji/polaris (v2)" from Apr 12, 2016, leads to the
following static checker warning:

	drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c:368 amdgpu_set_pp_dpm_sclk()
	warn: why is the last element skipped?

drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
   356  static ssize_t amdgpu_set_pp_dpm_sclk(struct device *dev,
   357                  struct device_attribute *attr,
   358                  const char *buf,
   359                  size_t count)
   360  {
   361          struct drm_device *ddev = dev_get_drvdata(dev);
   362          struct amdgpu_device *adev = ddev->dev_private;
   363          int ret;
   364          long level;
   365          uint32_t i, mask = 0;
   366          char sub_str[2];
   367  
   368          for (i = 0; i < strlen(buf) - 1; i++) {

strlen() returns the number of characters not counting the NUL
terminator.  I guess this assumes that the last character is a newline?
Could we check for that instead?

   369                  sub_str[0] = *(buf + i);
   370                  sub_str[1] = '\0';
   371                  ret = kstrtol(sub_str, 0, &level);
   372  
   373                  if (ret) {
   374                          count = -EINVAL;
   375                          goto fail;
   376                  }
   377                  mask |= 1 << level;
   378          }
   379  
   380          if (adev->pp_enabled)
   381                  amdgpu_dpm_force_clock_level(adev, PP_SCLK, mask);
   382  fail:
   383          return count;
   384  }

There are a couple other:
drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c:412 amdgpu_set_pp_dpm_mclk() warn: why is the last element skipped?
drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c:456 amdgpu_set_pp_dpm_pcie() warn: why is the last element skipped?

regards,
dan carpenter
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