[PATCH v2] i915/perf: Fix NULL deref bugs with drm_dbg() calls

[Harshit Mogalapalli]

When i915 perf interface is not available dereferencing it will lead to
NULL dereferences.

As returning -ENOTSUPP is pretty clear return when perf interface is not
available.

Fixes: 2fec539112e8 ("i915/perf: Replace DRM_DEBUG with driver specific drm_dbg 
call")
Suggested-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapa...@oracle.com>
---
v1 --> v2: Remove the debug calls as they don't add much value and
-ENOTSUPP is a good enough return value.
---
 drivers/gpu/drm/i915/i915_perf.c | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 2f3ecd7d4804..7b1c8de2f9cb 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -4227,11 +4227,8 @@ int i915_perf_open_ioctl(struct drm_device *dev, void 
*data,
        u32 known_open_flags;
        int ret;
 
-       if (!perf->i915) {
-               drm_dbg(&perf->i915->drm,
-                       "i915 perf interface not available for this system\n");
+       if (!perf->i915)
                return -ENOTSUPP;
-       }
 
        known_open_flags = I915_PERF_FLAG_FD_CLOEXEC |
                           I915_PERF_FLAG_FD_NONBLOCK |
@@ -4607,11 +4604,8 @@ int i915_perf_add_config_ioctl(struct drm_device *dev, 
void *data,
        struct i915_oa_reg *regs;
        int err, id;
 
-       if (!perf->i915) {
-               drm_dbg(&perf->i915->drm,
-                       "i915 perf interface not available for this system\n");
+       if (!perf->i915)
                return -ENOTSUPP;
-       }
 
        if (!perf->metrics_kobj) {
                drm_dbg(&perf->i915->drm,
@@ -4773,11 +4767,8 @@ int i915_perf_remove_config_ioctl(struct drm_device 
*dev, void *data,
        struct i915_oa_config *oa_config;
        int ret;
 
-       if (!perf->i915) {
-               drm_dbg(&perf->i915->drm,
-                       "i915 perf interface not available for this system\n");
+       if (!perf->i915)
                return -ENOTSUPP;
-       }
 
        if (i915_perf_stream_paranoid && !perfmon_capable()) {
                drm_dbg(&perf->i915->drm,
-- 
2.39.3