intel: Review use of errno.

Hitting this error lead to a segfault:

  intel_bufmgr_gem.c:919: Error mapping buffer 48607 (pixmap):
                          Cannot allocate memory.

because the errno was reused as the function return value after being
reset by the fprintf(), so caller thought the mapping had succeeded. The
convention established by libdrm is that the return value is the
negative errno and that uses of libdrm cannot trust the value of errno
afterwards, but must use the return code.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
index e9896e7..bb20f43 100644 (file)
--- a/intel/intel_bufmgr_gem.c
+++ b/intel/intel_bufmgr_gem.c
@@ -846,6 +846,7 @@ static int drm_intel_gem_bo_map(drm_intel_bo *bo, int write_enable)
                                    &mmap_arg);
                } while (ret == -1 && errno == EINTR);
                if (ret != 0) {
+                       ret = -errno;
                        fprintf(stderr,
                                "%s:%d: Error mapping buffer %d (%s): %s .\n",
                                __FILE__, __LINE__, bo_gem->gem_handle,
@@ -871,6 +872,7 @@ static int drm_intel_gem_bo_map(drm_intel_bo *bo, int write_enable)
                            &set_domain);
        } while (ret == -1 && errno == EINTR);
        if (ret != 0) {
+               ret = -errno;
                fprintf(stderr, "%s:%d: Error setting to CPU domain %d: %s\n",
                        __FILE__, __LINE__, bo_gem->gem_handle,
                        strerror(errno));
@@ -909,6 +911,7 @@ int drm_intel_gem_bo_map_gtt(drm_intel_bo *bo)
                                    &mmap_arg);
                } while (ret == -1 && errno == EINTR);
                if (ret != 0) {
+                       ret = -errno;
                        fprintf(stderr,
                                "%s:%d: Error preparing buffer map %d (%s): %s .\n",
                                __FILE__, __LINE__,
@@ -923,13 +926,14 @@ int drm_intel_gem_bo_map_gtt(drm_intel_bo *bo)
                                           MAP_SHARED, bufmgr_gem->fd,
                                           mmap_arg.offset);
                if (bo_gem->gtt_virtual == MAP_FAILED) {
+                       ret = -errno;
                        fprintf(stderr,
                                "%s:%d: Error mapping buffer %d (%s): %s .\n",
                                __FILE__, __LINE__,
                                bo_gem->gem_handle, bo_gem->name,
                                strerror(errno));
                        pthread_mutex_unlock(&bufmgr_gem->lock);
-                       return errno;
+                       return ret;
                }
        }
 
@@ -949,6 +953,7 @@ int drm_intel_gem_bo_map_gtt(drm_intel_bo *bo)
        } while (ret == -1 && errno == EINTR);
 
        if (ret != 0) {
+               ret = -errno;
                fprintf(stderr, "%s:%d: Error setting domain %d: %s\n",
                        __FILE__, __LINE__, bo_gem->gem_handle,
                        strerror(errno));
@@ -1077,12 +1082,13 @@ drm_intel_gem_bo_get_subdata(drm_intel_bo *bo, unsigned long offset,
                            &pread);
        } while (ret == -1 && errno == EINTR);
        if (ret != 0) {
+               ret = -errno;
                fprintf(stderr,
                        "%s:%d: Error reading data from buffer %d: (%d %d) %s .\n",
                        __FILE__, __LINE__, bo_gem->gem_handle, (int)offset,
                        (int)size, strerror(errno));
        }
-       return 0;
+       return ret;
 }
 
 /** Waits for all GPU rendering to the object to have completed. */
@@ -1289,17 +1295,20 @@ drm_intel_gem_bo_exec(drm_intel_bo *bo, int used,
                            &execbuf);
        } while (ret != 0 && errno == EAGAIN);
 
-       if (ret != 0 && errno == ENOMEM) {
-               fprintf(stderr,
-                       "Execbuffer fails to pin. "
-                       "Estimate: %u. Actual: %u. Available: %u\n",
-                       drm_intel_gem_estimate_batch_space(bufmgr_gem->exec_bos,
-                                                          bufmgr_gem->
-                                                          exec_count),
-                       drm_intel_gem_compute_batch_space(bufmgr_gem->exec_bos,
-                                                         bufmgr_gem->
-                                                         exec_count),
-                       (unsigned int)bufmgr_gem->gtt_size);
+       if (ret != 0) {
+               ret = -errno;
+               if (errno == ENOSPC) {
+                       fprintf(stderr,
+                               "Execbuffer fails to pin. "
+                               "Estimate: %u. Actual: %u. Available: %u\n",
+                               drm_intel_gem_estimate_batch_space(bufmgr_gem->exec_bos,
+                                                                  bufmgr_gem->
+                                                                  exec_count),
+                               drm_intel_gem_compute_batch_space(bufmgr_gem->exec_bos,
+                                                                 bufmgr_gem->
+                                                                 exec_count),
+                               (unsigned int)bufmgr_gem->gtt_size);
+               }
        }
        drm_intel_update_buffer_offsets(bufmgr_gem);
 
@@ -1317,7 +1326,7 @@ drm_intel_gem_bo_exec(drm_intel_bo *bo, int used,
        bufmgr_gem->exec_count = 0;
        pthread_mutex_unlock(&bufmgr_gem->lock);
 
-       return 0;
+       return ret;
 }
 
 static int
@@ -1606,7 +1615,7 @@ drm_intel_gem_check_aperture_space(drm_intel_bo **bo_array, int count)
        if (bufmgr_gem->available_fences) {
                total_fences = drm_intel_gem_total_fences(bo_array, count);
                if (total_fences > bufmgr_gem->available_fences)
-                       return -1;
+                       return -ENOSPC;
        }
 
        total = drm_intel_gem_estimate_batch_space(bo_array, count);
@@ -1618,7 +1627,7 @@ drm_intel_gem_check_aperture_space(drm_intel_bo **bo_array, int count)
                DBG("check_space: overflowed available aperture, "
                    "%dkb vs %dkb\n",
                    total / 1024, (int)bufmgr_gem->gtt_size / 1024);
-               return -1;
+               return -ENOSPC;
        } else {
                DBG("drm_check_space: total %dkb vs bufgr %dkb\n", total / 1024,
                    (int)bufmgr_gem->gtt_size / 1024);