[2/3] glx: Lift sending the MakeCurrent request to top-level code (v2)

Submitted by Adam Jackson on Dec. 5, 2017, 9:22 p.m.

Details

Message ID 20171205212205.2422-3-ajax@redhat.com
State New
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Series "GLX_EXT_no_config_context v4" ( rev: 1 ) in Mesa

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Commit Message

Adam Jackson Dec. 5, 2017, 9:22 p.m.
Somewhat terrifyingly, we never sent this for direct contexts, which
means the server never knew the context/drawable bindings.

To handle this sanely, pull the request code up out of the indirect
backend, and rewrite the context switch path to call it as appropriate.
This attempts to preserve the existing behavior of not calling unbind()
on the context if its refcount would not drop to zero, which is why the

Patch hide | download patch | download mbox

diff is a little uglier than I'd like.

Fixes glx-make-context, glx-multi-context-single-window and
glx-query-drawable-glx_fbconfig_id-window with both direct and indirect
contexts. glx-make-glxdrawable-current regresses, but I believe the test
is in error, as the fbconfig it uses to create the context is just
"something double-buffered and rgba" as opposed to "corresponds to the
visual I used to create the windows".

v2: Style fixups (Ian Romanick)

Signed-off-by: Adam Jackson <ajax@redhat.com>
---
 src/glx/glxcurrent.c   | 182 +++++++++++++++++++++++++++++++++++++------------
 src/glx/indirect_glx.c | 140 +++++++------------------------------
 2 files changed, 162 insertions(+), 160 deletions(-)

diff --git a/src/glx/glxcurrent.c b/src/glx/glxcurrent.c
index 9f8bf7cee1..0ce80670d2 100644
--- a/src/glx/glxcurrent.c
+++ b/src/glx/glxcurrent.c
@@ -165,17 +165,85 @@  glXGetCurrentDrawable(void)
    return gc->currentDrawable;
 }
 
-/**
- * Make a particular context current.
- *
- * \note This is in this file so that it can access dummyContext.
- */
+static Bool
+SendMakeCurrentRequest(Display * dpy, GLXContextID gc_id,
+                       GLXContextTag gc_tag, GLXDrawable draw,
+                       GLXDrawable read, GLXContextTag *out_tag)
+{
+   xGLXMakeCurrentReply reply;
+   Bool ret;
+   int opcode = __glXSetupForCommand(dpy);
+
+   LockDisplay(dpy);
+
+   if (draw == read) {
+      xGLXMakeCurrentReq *req;
+
+      GetReq(GLXMakeCurrent, req);
+      req->reqType = opcode;
+      req->glxCode = X_GLXMakeCurrent;
+      req->drawable = draw;
+      req->context = gc_id;
+      req->oldContextTag = gc_tag;
+   }
+   else {
+      struct glx_display *priv = __glXInitialize(dpy);
+
+      if ((priv->majorVersion > 1) || (priv->minorVersion >= 3)) {
+         xGLXMakeContextCurrentReq *req;
+
+         GetReq(GLXMakeContextCurrent, req);
+         req->reqType = opcode;
+         req->glxCode = X_GLXMakeContextCurrent;
+         req->drawable = draw;
+         req->readdrawable = read;
+         req->context = gc_id;
+         req->oldContextTag = gc_tag;
+      }
+      else {
+         xGLXVendorPrivateWithReplyReq *vpreq;
+         xGLXMakeCurrentReadSGIReq *req;
+
+         GetReqExtra(GLXVendorPrivateWithReply,
+                     sz_xGLXMakeCurrentReadSGIReq -
+                     sz_xGLXVendorPrivateWithReplyReq, vpreq);
+         req = (xGLXMakeCurrentReadSGIReq *) vpreq;
+         req->reqType = opcode;
+         req->glxCode = X_GLXVendorPrivateWithReply;
+         req->vendorCode = X_GLXvop_MakeCurrentReadSGI;
+         req->drawable = draw;
+         req->readable = read;
+         req->context = gc_id;
+         req->oldContextTag = gc_tag;
+      }
+   }
+
+   ret = _XReply(dpy, (xReply *) &reply, 0, False);
+
+   if (out_tag)
+      *out_tag = reply.contextTag;
+
+   UnlockDisplay(dpy);
+   SyncHandle();
+
+   return ret;
+}
+
+static void
+SetGC(struct glx_context *gc, Display *dpy, GLXDrawable draw, GLXDrawable read)
+{
+   gc->currentDpy = dpy;
+   gc->currentDrawable = draw;
+   gc->currentReadable = read;
+}
+
 static Bool
 MakeContextCurrent(Display * dpy, GLXDrawable draw,
                    GLXDrawable read, GLXContext gc_user)
 {
    struct glx_context *gc = (struct glx_context *) gc_user;
    struct glx_context *oldGC = __glXGetCurrentContext();
+   Bool ret = GL_FALSE;
 
    /* Make sure that the new context has a nonzero ID.  In the request,
     * a zero context ID is used only to mean that we bind to no current
@@ -186,59 +254,87 @@  MakeContextCurrent(Display * dpy, GLXDrawable draw,
    }
 
    _glapi_check_multithread();
-
    __glXLock();
+
    if (oldGC == gc &&
-       gc->currentDrawable == draw && gc->currentReadable == read) {
-      __glXUnlock();
-      return True;
+       gc->currentDrawable == draw &&
+       gc->currentReadable == read) {
+      /* Same context and drawables: no op, just return */
+      ret = GL_TRUE;
    }
 
-   if (oldGC != &dummyContext) {
-      if (--oldGC->thread_refcount == 0) {
-	 oldGC->vtable->unbind(oldGC, gc);
-	 oldGC->currentDpy = 0;
+   else if (oldGC == gc) {
+      /* Same context and new drawbles: update drawable bindings */
+      if (!SendMakeCurrentRequest(dpy, gc->xid, gc->currentContextTag,
+                                  draw, read, &gc->currentContextTag)) {
+         goto out;
       }
-   }
 
-   if (gc) {
-      /* Attempt to bind the context.  We do this before mucking with
-       * gc and __glXSetCurrentContext to properly handle our state in
-       * case of an error.
-       *
-       * If an error occurs, set the Null context since we've already
-       * blown away our old context.  The caller is responsible for
-       * figuring out how to handle setting a valid context.
-       */
-      if (gc->vtable->bind(gc, oldGC, draw, read) != Success) {
+      if (gc->vtable->bind(gc, gc, draw, read) != Success) {
          __glXSetCurrentContextNull();
-         __glXUnlock();
-         __glXSendError(dpy, GLXBadContext, None, X_GLXMakeContextCurrent,
-                        False);
-         return GL_FALSE;
+         goto out;
       }
+   }
 
-      if (gc->thread_refcount == 0) {
-         gc->currentDpy = dpy;
-         gc->currentDrawable = draw;
-         gc->currentReadable = read;
+   else {
+      /* Different contexts: release the old, bind the new */
+      if (oldGC != &dummyContext) {
+         if (--oldGC->thread_refcount == 0) {
+            if (!SendMakeCurrentRequest(dpy, None, oldGC->currentContextTag,
+                                        None, None,
+					&oldGC->currentContextTag)) {
+               goto out;
+            }
+
+            oldGC->vtable->unbind(oldGC, gc);
+
+            if (oldGC->xid == None) {
+               /* destroyed context, free it */
+               oldGC->vtable->destroy(oldGC);
+            } else {
+               SetGC(oldGC, NULL, None, None);
+            }
+         }
       }
-      gc->thread_refcount++;
-      __glXSetCurrentContext(gc);
-   } else {
       __glXSetCurrentContextNull();
-   }
 
-   if (oldGC->thread_refcount == 0 && oldGC != &dummyContext && oldGC->xid == None) {
-      /* We are switching away from a context that was
-       * previously destroyed, so we need to free the memory
-       * for the old handle. */
-      oldGC->vtable->destroy(oldGC);
+      if (gc) {
+         /*
+          * MESA_multithread_makecurrent makes this complicated. We need to send
+          * the request if the new context is
+          *
+          * a) indirect (may be current to another client), or
+          * b) (direct and) newly being made current, or
+          * c) (direct and) being bound to new drawables
+          */
+         Bool new_drawables = gc->currentReadable != read ||
+                              gc->currentDrawable != draw;
+
+         if (!gc->isDirect || !gc->thread_refcount || new_drawables) {
+            if (!SendMakeCurrentRequest(dpy, gc->xid, oldGC->currentContextTag,
+                                        draw, read, &gc->currentContextTag)) {
+               goto out;
+            }
+         }
+
+         if (gc->vtable->bind(gc, oldGC, draw, read) != Success) {
+            __glXSendError(dpy, GLXBadContext, None, X_GLXMakeContextCurrent,
+                           False);
+            goto out;
+         }
+
+         if (gc->thread_refcount == 0) {
+            SetGC(gc, dpy, draw, read);
+         }
+         gc->thread_refcount++;
+         __glXSetCurrentContext(gc);
+      }
    }
+   ret = GL_TRUE;
 
+out:
    __glXUnlock();
-
-   return GL_TRUE;
+   return ret;
 }
 
 
diff --git a/src/glx/indirect_glx.c b/src/glx/indirect_glx.c
index 5482d768ff..d4b77b3b6e 100644
--- a/src/glx/indirect_glx.c
+++ b/src/glx/indirect_glx.c
@@ -61,135 +61,41 @@  indirect_destroy_context(struct glx_context *gc)
    free((char *) gc);
 }
 
-static Bool
-SendMakeCurrentRequest(Display * dpy, GLXContextID gc_id,
-                       GLXContextTag gc_tag, GLXDrawable draw,
-                       GLXDrawable read, GLXContextTag *out_tag)
-{
-   xGLXMakeCurrentReply reply;
-   Bool ret;
-   int opcode = __glXSetupForCommand(dpy);
-
-   LockDisplay(dpy);
-
-   if (draw == read) {
-      xGLXMakeCurrentReq *req;
-
-      GetReq(GLXMakeCurrent, req);
-      req->reqType = opcode;
-      req->glxCode = X_GLXMakeCurrent;
-      req->drawable = draw;
-      req->context = gc_id;
-      req->oldContextTag = gc_tag;
-   }
-   else {
-      struct glx_display *priv = __glXInitialize(dpy);
-
-      /* If the server can support the GLX 1.3 version, we should
-       * perfer that.  Not only that, some servers support GLX 1.3 but
-       * not the SGI extension.
-       */
-
-      if ((priv->majorVersion > 1) || (priv->minorVersion >= 3)) {
-         xGLXMakeContextCurrentReq *req;
-
-         GetReq(GLXMakeContextCurrent, req);
-         req->reqType = opcode;
-         req->glxCode = X_GLXMakeContextCurrent;
-         req->drawable = draw;
-         req->readdrawable = read;
-         req->context = gc_id;
-         req->oldContextTag = gc_tag;
-      }
-      else {
-         xGLXVendorPrivateWithReplyReq *vpreq;
-         xGLXMakeCurrentReadSGIReq *req;
-
-         GetReqExtra(GLXVendorPrivateWithReply,
-                     sz_xGLXMakeCurrentReadSGIReq -
-                     sz_xGLXVendorPrivateWithReplyReq, vpreq);
-         req = (xGLXMakeCurrentReadSGIReq *) vpreq;
-         req->reqType = opcode;
-         req->glxCode = X_GLXVendorPrivateWithReply;
-         req->vendorCode = X_GLXvop_MakeCurrentReadSGI;
-         req->drawable = draw;
-         req->readable = read;
-         req->context = gc_id;
-         req->oldContextTag = gc_tag;
-      }
-   }
-
-   ret = _XReply(dpy, (xReply *) &reply, 0, False);
-
-   if (out_tag)
-      *out_tag = reply.contextTag;
-
-   UnlockDisplay(dpy);
-   SyncHandle();
-
-   return ret;
-}
-
 static int
 indirect_bind_context(struct glx_context *gc, struct glx_context *old,
 		      GLXDrawable draw, GLXDrawable read)
 {
-   GLXContextTag tag;
-   Display *dpy = gc->psc->dpy;
-   Bool sent;
-
-   if (old != &dummyContext && !old->isDirect && old->psc->dpy == dpy) {
-      tag = old->currentContextTag;
-      old->currentContextTag = 0;
-   } else {
-      tag = 0;
+   __GLXattribute *state = gc->client_state_private;
+
+   if (!IndirectAPI)
+      IndirectAPI = __glXNewIndirectAPI();
+   _glapi_set_dispatch(IndirectAPI);
+
+   /* The indirect vertex array state must to be initialised after we
+    * have setup the context, as it needs to query server attributes.
+    *
+    * At the point this is called gc->currentDpy is not initialized
+    * nor is the thread's current context actually set. Hence the
+    * cleverness before the GetString calls.
+    */
+   if (state && state->array_state == NULL) {
+      gc->currentDpy = gc->psc->dpy;
+      __glXSetCurrentContext(gc);
+      __glXSetCurrentContext(gc);
+      __indirect_glGetString(GL_EXTENSIONS);
+      __indirect_glGetString(GL_VERSION);
+      __glXInitVertexArrayState(gc);
    }
 
-   sent = SendMakeCurrentRequest(dpy, gc->xid, tag, draw, read,
-				 &gc->currentContextTag);
-
-   if (sent) {
-      if (!IndirectAPI)
-         IndirectAPI = __glXNewIndirectAPI();
-      _glapi_set_dispatch(IndirectAPI);
-
-      /* The indirect vertex array state must to be initialised after we
-       * have setup the context, as it needs to query server attributes.
-       *
-       * At the point this is called gc->currentDpy is not initialized
-       * nor is the thread's current context actually set. Hence the
-       * cleverness before the GetString calls.
-       */
-      __GLXattribute *state = gc->client_state_private;
-      if (state && state->array_state == NULL) {
-         gc->currentDpy = gc->psc->dpy;
-         __glXSetCurrentContext(gc);
-         __indirect_glGetString(GL_EXTENSIONS);
-         __indirect_glGetString(GL_VERSION);
-         __glXInitVertexArrayState(gc);
-      }
-   }
+   if (state != NULL && state->array_state != NULL)
+      return Success;
 
-   return !sent;
+   return BadAlloc;
 }
 
 static void
 indirect_unbind_context(struct glx_context *gc, struct glx_context *new)
 {
-   Display *dpy = gc->psc->dpy;
-
-   if (gc == new)
-      return;
-   
-   /* We are either switching to no context, away from an indirect
-    * context to a direct context or from one dpy to another and have
-    * to send a request to the dpy to unbind the previous context.
-    */
-   if (!new || new->isDirect || new->psc->dpy != dpy) {
-      SendMakeCurrentRequest(dpy, None, gc->currentContextTag, None, None,
-                             NULL);
-      gc->currentContextTag = 0;
-   }
 }
 
 static void

Comments

On 5 December 2017 at 21:22, Adam Jackson <ajax@redhat.com> wrote:
> Somewhat terrifyingly, we never sent this for direct contexts, which
> means the server never knew the context/drawable bindings.
>
> To handle this sanely, pull the request code up out of the indirect
> backend, and rewrite the context switch path to call it as appropriate.
> This attempts to preserve the existing behavior of not calling unbind()
> on the context if its refcount would not drop to zero, which is why the
> diff is a little uglier than I'd like.
>
> Fixes glx-make-context, glx-multi-context-single-window and
> glx-query-drawable-glx_fbconfig_id-window with both direct and indirect
> contexts. glx-make-glxdrawable-current regresses, but I believe the test
> is in error, as the fbconfig it uses to create the context is just
> "something double-buffered and rgba" as opposed to "corresponds to the
> visual I used to create the windows".
>
> v2: Style fixups (Ian Romanick)
>
Adam, can we make this 1/3 and cc stable?

> Signed-off-by: Adam Jackson <ajax@redhat.com>
> ---
>  src/glx/glxcurrent.c   | 182 +++++++++++++++++++++++++++++++++++++------------
>  src/glx/indirect_glx.c | 140 +++++++------------------------------
>  2 files changed, 162 insertions(+), 160 deletions(-)
>
> diff --git a/src/glx/glxcurrent.c b/src/glx/glxcurrent.c
> index 9f8bf7cee1..0ce80670d2 100644
> --- a/src/glx/glxcurrent.c
> +++ b/src/glx/glxcurrent.c
> @@ -165,17 +165,85 @@ glXGetCurrentDrawable(void)
>     return gc->currentDrawable;
>  }
>
> -/**
> - * Make a particular context current.
> - *
> - * \note This is in this file so that it can access dummyContext.
> - */
> +static Bool
> +SendMakeCurrentRequest(Display * dpy, GLXContextID gc_id,
> +                       GLXContextTag gc_tag, GLXDrawable draw,
> +                       GLXDrawable read, GLXContextTag *out_tag)
> +{
Nit: I would keep the code move a separate patch, I might be too
pedantic though ;-)


>  static Bool
>  MakeContextCurrent(Display * dpy, GLXDrawable draw,
>                     GLXDrawable read, GLXContext gc_user)
>  {
>     struct glx_context *gc = (struct glx_context *) gc_user;
>     struct glx_context *oldGC = __glXGetCurrentContext();
> +   Bool ret = GL_FALSE;
Bool is True False. Then again I would drop the variable and
__glXUnlock/return as applicable.


> -      if (gc->vtable->bind(gc, oldGC, draw, read) != Success) {
> +      if (gc->vtable->bind(gc, gc, draw, read) != Success) {
>           __glXSetCurrentContextNull();
This line seems inconsistent/wrong.

The glXMakeCurrent manpage says "If False is returned, the previously
current rendering context and drawable (if any) remain unchanged."


> +         if (gc->thread_refcount == 0) {
> +            SetGC(gc, dpy, draw, read);
> +         }
Nit: drop the brackets for the single like if statement.


> +   if (state != NULL && state->array_state != NULL)
> +      return Success;
>
> -   return !sent;
> +   return BadAlloc;
Nit: diverge the exception (error path) keeping the main codeflow straight.

   if (state == NULL || state->array_state == NULL)
      return BadAlloc;

   return Success;

>  }
>
>  static void
>  indirect_unbind_context(struct glx_context *gc, struct glx_context *new)
>  {
Nit: add a comment to link "nothing to do here - MakeContextCurrent
sends the required protocol as applicable"

-Emil
On Wed, 2017-12-06 at 15:14 +0000, Emil Velikov wrote:

> > -      if (gc->vtable->bind(gc, oldGC, draw, read) != Success) {
> > +      if (gc->vtable->bind(gc, gc, draw, read) != Success) {
> >           __glXSetCurrentContextNull();
> 
> This line seems inconsistent/wrong.
> 
> The glXMakeCurrent manpage says "If False is returned, the previously
> current rendering context and drawable (if any) remain unchanged."

Ugh. That's not really possible to get perfectly right, there are
unrecoverable states (think MakeCurrent away from a context that's been
deleted, or whose current drawable is a destroyed window). Still, I
suppose we should try at least a little.

- ajax
On 6 December 2017 at 19:25, Adam Jackson <ajax@redhat.com> wrote:
> On Wed, 2017-12-06 at 15:14 +0000, Emil Velikov wrote:
>
>> > -      if (gc->vtable->bind(gc, oldGC, draw, read) != Success) {
>> > +      if (gc->vtable->bind(gc, gc, draw, read) != Success) {
>> >           __glXSetCurrentContextNull();
>>
>> This line seems inconsistent/wrong.
>>
>> The glXMakeCurrent manpage says "If False is returned, the previously
>> current rendering context and drawable (if any) remain unchanged."
>
> Ugh. That's not really possible to get perfectly right, there are
> unrecoverable states (think MakeCurrent away from a context that's been
> deleted, or whose current drawable is a destroyed window). Still, I
> suppose we should try at least a little.
>
From a quick look delaying the unbind call should address that. I'd
drop the __glXSetCurrentContextNull call for now and keep the rest of
the yak shaving at a later stage.

Just noticed some copy/paste damage

 indirect_bind_context(struct glx_context *gc, struct glx_context *old,
                      GLXDrawable draw, GLXDrawable read)
 {

+    * cleverness before the GetString calls.
+    */
+   if (state && state->array_state == NULL) {
+      gc->currentDpy = gc->psc->dpy;
+      __glXSetCurrentContext(gc);
+      __glXSetCurrentContext(gc);

__glXSetCurrentContext should be only once.

Thanks
Emil