[Mesa-stable] [PATCH] i965: Properly reject __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS when __DRI2_ROBUSTNESS is not enabled

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

Only allow __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS in brwCreateContext if
intelInitScreen2 also enabled __DRI2_ROBUSTNESS (thereby enabling
GLX_ARB_create_context).

This fixes a regression in the piglit test
"glx/GLX_ARB_create_context/invalid flag"

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Reported-by: Paul Berry <stereotype441 at gmail.com>
Cc: "10.0" <mesa-stable at lists.freedesktop.org>
---
The patch that causes the regression (9b1c686) hasn't been picked to
10.0 yet, so this patch should get squashed with it when they're both
picked.

 src/mesa/drivers/dri/i965/brw_context.c  | 13 ++++++++++---
 src/mesa/drivers/dri/i965/intel_screen.c |  4 +++-
 src/mesa/drivers/dri/i965/intel_screen.h |  5 +++++
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 67ac01c..948f3bd 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -558,9 +558,16 @@ brwCreateContext(gl_api api,
    struct dd_function_table functions;
    struct gl_config visual;
 
-   if (flags & ~(__DRI_CTX_FLAG_DEBUG
-                 | __DRI_CTX_FLAG_FORWARD_COMPATIBLE
-                 | __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS)) {
+   /* Only allow the __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS flag if the kernel
+    * provides us with context reset notifications.
+    */
+   uint32_t allowed_flags = __DRI_CTX_FLAG_DEBUG
+      | __DRI_CTX_FLAG_FORWARD_COMPATIBLE;
+
+   if (/*false &&*/ screen->has_context_reset_notification)
+      allowed_flags |= __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS;
+
+   if (flags & ~allowed_flags) {
       *dri_ctx_error = __DRI_CTX_ERROR_UNKNOWN_FLAG;
       return false;
    }
diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index 051c000..39c2f35 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -1344,7 +1344,9 @@ __DRIconfig **intelInitScreen2(__DRIscreen *psp)
 
    const int ret = drmIoctl(psp->fd, DRM_IOCTL_I915_GET_RESET_STATS, &stats);
 
-   psp->extensions = (ret == -1 && errno == EINVAL)
+   intelScreen->has_context_reset_notification = (ret != -1 || errno != EINVAL);
+
+   psp->extensions = !intelScreen->has_context_reset_notification
       ? intelScreenExtensions : intelRobustScreenExtensions;
 
    return (const __DRIconfig**) intel_screen_make_configs(psp);
diff --git a/src/mesa/drivers/dri/i965/intel_screen.h b/src/mesa/drivers/dri/i965/intel_screen.h
index 2e3043e..924e1f2 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.h
+++ b/src/mesa/drivers/dri/i965/intel_screen.h
@@ -50,6 +50,11 @@ struct intel_screen
 
    bool hw_has_swizzling;
 
+   /**
+    * Does the kernel support context reset notifications?
+    */
+   bool has_context_reset_notification;
+
    dri_bufmgr *bufmgr;
 
    /**
-- 
1.8.1.4