Bug 16210

Running test case of bug #10219 (attachment #9027 [details]), it will seg fault when draw primitives. The case uses mipmap and sets texture lod.

The backtrace info:

(gdb) bt
#0  intel_finalize_mipmap_tree (intel=0x8075750, unit=0)
    at intel_tex_validate.c:146
#1  0xb7a2e672 in i915_update_tex_unit (intel=0x8075750, unit=0, ss3=32)
    at i915_texstate.c:138
#2  0xb7a2eb3f in i915UpdateTextureState (intel=0x8075750)
    at i915_texstate.c:352
#3  0xb7a469ef in intelRunPipeline (ctx=0x8075750) at intel_tris.c:895
#4  0xb7ae7757 in _tnl_draw_prims (ctx=0x8075750, arrays=0x80a6708, 
    prim=0x80a5264, nr_prims=1, ib=0x0, min_index=0, max_index=3)
    at tnl/t_draw.c:402
#5  0xb7adfe0a in vbo_exec_vtx_flush (exec=0x80a5140)
    at vbo/vbo_exec_draw.c:215
#6  0xb7adbef0 in vbo_exec_FlushVertices (ctx=0x8075750, flags=1)
    at vbo/vbo_exec_api.c:700
#7  0xb7b814e2 in _mesa_ReadPixels (x=0, y=0, width=64, height=64, 
    format=6407, type=5126, pixels=0x8059a20) at main/drawpix.c:294
#8  0x080492c3 in display () at texture_lod_10219.c:145
#9  0xb7e92865 in processWindowWorkList (window=0x806c470) at glut_event.c:1306
#10 0xb7e934d1 in glutMainLoop () at glut_event.c:1353
#11 0x0804938f in main (argc=Cannot access memory at address 0x6
) at texture_lod_10219.c:162