[Libreoffice-commits] core.git: opencl/inc

[Giuseppe Bilotta]

 opencl/inc/opencl_device_selection.h |   26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

New commits:
commit 0d4204e87f89839ee0b4ca33e1684626599e4315
Author: Giuseppe Bilotta <giuseppe.bilotta at gmail.com>
Date:   Mon Mar 2 00:09:29 2015 +0100

    OpenCL: correctly handle platforms without devices
    
    When an OpenCL platform has no devices (of the requested type), calls to
    clGetDeviceIDs() are required to return with the error value
    CL_DEVICE_NOT_FOUND.
    
    Some platforms (e.g. Clover as of Mesa 10.4.2) do not touch their output
    parameters in such cases, which means that in some conditions the `num`
    variable where the number of devices of the platform should be stored
    may be used uninitialized. This can lead to segmentations faults in the
    subsequent calls to clGetDeviceInfo().
    
    Simply reinitializing num to 0 is sufficient to prevent the segfault in
    the case of Mesa, but proper error handling is included for
    completeness.
    
    Change-Id: Ia25192f6aa953838a545a9e7c9fca050d2703b60
    Reviewed-on: https://gerrit.libreoffice.org/14700
    Tested-by: Jenkins <ci at libreoffice.org>
    Reviewed-by: Tor Lillqvist <tml at collabora.com>

diff --git a/opencl/inc/opencl_device_selection.h b/opencl/inc/opencl_device_selection.h
index 7e0754b..14ec814 100644
--- a/opencl/inc/opencl_device_selection.h
+++ b/opencl/inc/opencl_device_selection.h
@@ -121,8 +121,17 @@ inline ds_status initDSProfile(ds_profile** p, const char* version)
     numDevices = 0;
     for (i = 0; i < (unsigned int)numPlatforms; i++)
     {
-        cl_uint num;
-        clGetDeviceIDs(platforms[i], CL_DEVICE_TYPE_ALL, 0, NULL, &num);
+        cl_uint num = 0;
+        cl_int err = clGetDeviceIDs(platforms[i], CL_DEVICE_TYPE_ALL, 0, NULL, &num);
+        if (err != CL_SUCCESS)
+        {
+            /* we want to catch at least the case when the call returns
+             * CL_DEVICE_NOT_FOUND (i.e. no devices), because some platforms
+             * don't set num to 0 in this case; but in fact this is a good
+             * thing to do for _any_ error returned by the call
+             */
+            num = 0;
+        }
         numDevices += num;
     }
     if (numDevices != 0)
@@ -148,12 +157,21 @@ inline ds_status initDSProfile(ds_profile** p, const char* version)
     next = 0;
     for (i = 0; i < (unsigned int)numPlatforms; i++)
     {
-        cl_uint num;
+        cl_uint num = 0;
         unsigned j;
         char vendor[256];
         if (clGetPlatformInfo(platforms[i], CL_PLATFORM_VENDOR, sizeof(vendor), vendor, NULL) != CL_SUCCESS)
             vendor[0] = '\0';
-        clGetDeviceIDs(platforms[i], CL_DEVICE_TYPE_ALL, numDevices, devices, &num);
+        cl_int err = clGetDeviceIDs(platforms[i], CL_DEVICE_TYPE_ALL, numDevices, devices, &num);
+        if (err != CL_SUCCESS)
+        {
+            /* we want to catch at least the case when the call returns
+             * CL_DEVICE_NOT_FOUND (i.e. no devices), because some platforms
+             * don't set num to 0 in this case; but in fact this is a good
+             * thing to do for _any_ error returned by the call
+             */
+            num = 0;
+        }
         for (j = 0; j < num; j++, next++)
         {
             char buffer[DS_DEVICE_NAME_LENGTH];