drm/radeon: Make r100_cp_ring_info() and radeon_ring_gfx() safe (v2)

commit 0eb3448aa6b31fbf24c31756aba7940cac5ad6b8 upstream.

Prevent NULL pointer dereference in case when radeon_ring_fini() did it's job.

Reading of r100_cp_ring_info and radeon_ring_gfx debugfs entries will lead to a KP if ring buffer was deallocated, e.g. on failed ring test.
Seen on PA-RISC machine having "radeon: ring test failed (scratch(0x8504)=0xCAFEDEAD)" issue.

v2: agd5f: add some parens around ring->ready check

Signed-off-by: Alex Ivanov <gnidorah@p0n4ik.tk>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index d0314ecbd7c18ecbd0f250b48efb3023eaf2d3ae..46470dd7c7102fad247e51a7cc3f538c6db6fbf8 100644 (file)
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -2935,9 +2935,11 @@ static int r100_debugfs_cp_ring_info(struct seq_file *m, void *data)
        seq_printf(m, "CP_RB_RPTR 0x%08x\n", rdp);
        seq_printf(m, "%u free dwords in ring\n", ring->ring_free_dw);
        seq_printf(m, "%u dwords in ring\n", count);
-       for (j = 0; j <= count; j++) {
-               i = (rdp + j) & ring->ptr_mask;
-               seq_printf(m, "r[%04d]=0x%08x\n", i, ring->ring[i]);
+       if (ring->ready) {
+               for (j = 0; j <= count; j++) {
+                       i = (rdp + j) & ring->ptr_mask;
+                       seq_printf(m, "r[%04d]=0x%08x\n", i, ring->ring[i]);
+               }
        }
        return 0;
 }

diff --git a/drivers/gpu/drm/radeon/radeon_ring.c b/drivers/gpu/drm/radeon/radeon_ring.c
index 83f6295a0e5e00247e55dd7f8045227b380fc22c..6e0f4809bda09c0e3c966cd06868a563050c2168 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_ring.c
+++ b/drivers/gpu/drm/radeon/radeon_ring.c
@@ -823,9 +823,11 @@ static int radeon_debugfs_ring_info(struct seq_file *m, void *data)
         * packet that is the root issue
         */
        i = (ring->rptr + ring->ptr_mask + 1 - 32) & ring->ptr_mask;
-       for (j = 0; j <= (count + 32); j++) {
-               seq_printf(m, "r[%5d]=0x%08x\n", i, ring->ring[i]);
-               i = (i + 1) & ring->ptr_mask;
+       if (ring->ready) {
+               for (j = 0; j <= (count + 32); j++) {
+                       seq_printf(m, "r[%5d]=0x%08x\n", i, ring->ring[i]);
+                       i = (i + 1) & ring->ptr_mask;
+               }
        }
        return 0;
 }