ozone: drm: Add more debug details when dmabuf mmap fails.

ui/ozone/platform/drm/common/client_native_pixmap_dmabuf.cc

Index: ui/ozone/platform/drm/common/client_native_pixmap_dmabuf.cc
diff --git a/ui/ozone/platform/drm/common/client_native_pixmap_dmabuf.cc b/ui/ozone/platform/drm/common/client_native_pixmap_dmabuf.cc
index 7dbb1d481a628d26765811c099b8534a0bba51e5..85ecd31cdfffe70c74d04372919cd0d9160ca76d 100644
--- a/ui/ozone/platform/drm/common/client_native_pixmap_dmabuf.cc
+++ b/ui/ozone/platform/drm/common/client_native_pixmap_dmabuf.cc
@@ -10,8 +10,10 @@
 #include <sys/mman.h>
 #include <xf86drm.h>
 
+#include "base/debug/crash_logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/process/memory.h"
+#include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event.h"
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 6, 0)
@@ -80,8 +82,22 @@ ClientNativePixmapDmaBuf::ClientNativePixmapDmaBuf(
   data_ = mmap(nullptr, map_size, (PROT_READ | PROT_WRITE), MAP_SHARED,
                dmabuf_fd_.get(), 0);
   if (data_ == MAP_FAILED) {
-    PLOG(ERROR) << "Failed mmap().";
-    base::TerminateBecauseOutOfMemory(map_size);
+    logging::SystemErrorCode mmap_error = logging::GetLastSystemErrorCode();

[reveman, 2017/02/24 00:46:18]

nit: please add a TODO comment with a bug reference here for removing this
temporary diagnostics when we've been able to determine what's causing these
failures

[Daniele Castagna, 2017/02/24 01:18:21]

Done.

+    bool fd_valid = fcntl(dmabuf_fd_.get(), F_GETFD) != -1 ||
+                    logging::GetLastSystemErrorCode() != EBADF;
+    std::string mmap_params = base::StringPrintf(
+        "(addr=nullptr, length=%zu, prot=(PROT_READ | PROT_WRITE), "
+        "flags=MAP_SHARED, fd=%d[valid=%d], offset=0)",
+        map_size, dmabuf_fd_.get(), fd_valid);
+    base::debug::ScopedCrashKey params_crash_key("mmap_params", mmap_params);
+    base::debug::ScopedCrashKey size_crash_key("buffer_size", size.ToString());
+    base::debug::ScopedCrashKey errno_crash_key(
+        "errno", logging::SystemErrorCodeToString(mmap_error));
+    if (mmap_error == ENOMEM) {
+      base::TerminateBecauseOutOfMemory(map_size);
+    } else {

[reveman, 2017/02/24 00:46:18]

nit: remove else as base::TerminateBecauseOutOfMemory will never return

[Daniele Castagna, 2017/02/24 01:18:21]

Done.

+      CHECK(false) << "Failed to mmap dmabuf.";
+    }
   }
 }