[EGIT] [core/efl] master 02/02: evas-wayland-shm: Minimize race condition when finding free leaf

[Christopher Michael]

devilhorns pushed a commit to branch master.

http://git.enlightenment.org/core/efl.git/commit/?id=c4e9d294413004bb8253513f77690dfccb8a6d43

commit c4e9d294413004bb8253513f77690dfccb8a6d43
Author: Chris Michael <cp.mich...@samsung.com>
Date:   Wed Apr 29 11:49:49 2015 -0400

    evas-wayland-shm: Minimize race condition when finding free leaf
    
    Summary: This fixes a possible race condition that could happen when
    using more than 2 buffers. Instead of searching for a free buffer in
    various places, find a free buffer when evas requests the buffer data
    and save that free buffer as the 'current buffer'
    
    @fix
    
    Signed-off-by: Chris Michael <cp.mich...@samsung.com>
---
 src/modules/evas/engines/wayland_shm/evas_shm.c | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/src/modules/evas/engines/wayland_shm/evas_shm.c 
b/src/modules/evas/engines/wayland_shm/evas_shm.c
index 0a05f03..3cea7d2 100644
--- a/src/modules/evas/engines/wayland_shm/evas_shm.c
+++ b/src/modules/evas/engines/wayland_shm/evas_shm.c
@@ -412,23 +412,16 @@ _evas_shm_surface_swap(Shm_Surface *surface, 
Eina_Rectangle *rects, unsigned int
 
    LOGFN(__FILE__, __LINE__, __FUNCTION__);
 
-   for (; i < surface->num_buff; i++)
-     {
-        if (surface->leaf[i].busy) continue;
-        if ((!leaf) || (leaf->valid))
-          {
-             leaf = &surface->leaf[i];
-             break;
-          }
-     }
+   leaf = &surface->leaf[surface->curr_buff];
+   if (!leaf) return;
 
-   if (!leaf)
+   if (leaf->busy)
      {
-        /* WRN("All buffers held by server"); */
+        WRN("Trying to use a busy buffer");
         return;
      }
 
-   /* DBG("Current Leaf %d", (int)(leaf - &surface->leaf[0])); */
+   DBG("Current Leaf %d", (int)(leaf - &surface->leaf[0]));
 
    wl_surface_attach(surface->surface, leaf->data->buffer, 0, 0);
 
@@ -450,8 +443,6 @@ _evas_shm_surface_swap(Shm_Surface *surface, Eina_Rectangle 
*rects, unsigned int
    surface->dx = 0;
    surface->dy = 0;
    surface->redraw = EINA_TRUE;
-   surface->last_buff = surface->curr_buff;
-   surface->curr_buff = (int)(leaf - &surface->leaf[0]);
 }
 
 void *
@@ -477,7 +468,7 @@ _evas_shm_surface_data_get(Shm_Surface *surface, int *w, 
int *h)
 
    if (!leaf)
      {
-        /* WRN("All buffers held by server"); */
+        WRN("All buffers held by server");
         return NULL;
      }
 
@@ -486,6 +477,9 @@ _evas_shm_surface_data_get(Shm_Surface *surface, int *w, 
int *h)
    if (w) *w = leaf->w;
    if (h) *h = leaf->h;
 
+   surface->last_buff = surface->curr_buff;
+   surface->curr_buff = (int)(leaf - &surface->leaf[0]);
+
    return leaf->data->map;
 }
 

--