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drm/atomic: Don't overrun the connector array when hotplugging 

Yet another fallout from not considering DP MST hotplug. With the
previous patches we have stable indices, but it might still happen
that a connector gets added between when we allocate the array and
when we actually add a connector. Especially when we back off due to
ww mutex contention or similar issues.

So store the sizes of the arrays in struct drm_atomic_state and double
check them. We don't really care about races except that we want to
use a consistent value, so ACCESS_ONCE is all we need. And if we
indeed notice that we'd overrun the array then just give up and
restart the entire ioctl.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Daniel Vetter 2014-11-19 18:38:08 +01:00 committed by Dave Airlie
parent 6f75cea66c
commit f52b69f1ec
3 changed files with 31 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
drivers/gpu/drm/drm_atomic.c
View File

@ -56,6 +56,8 @@ drm_atomic_state_alloc(struct drm_device *dev)
if (!state)
return NULL;
state->num_connector = ACCESS_ONCE(dev->mode_config.num_connector);
state->crtcs = kcalloc(dev->mode_config.num_crtc,
sizeof(*state->crtcs), GFP_KERNEL);
if (!state->crtcs)
@ -72,12 +74,12 @@ drm_atomic_state_alloc(struct drm_device *dev)
sizeof(*state->plane_states), GFP_KERNEL);
if (!state->plane_states)
goto fail;
state->connectors = kcalloc(dev->mode_config.num_connector,
state->connectors = kcalloc(state->num_connector,
sizeof(*state->connectors),
GFP_KERNEL);
if (!state->connectors)
goto fail;
state->connector_states = kcalloc(dev->mode_config.num_connector,
state->connector_states = kcalloc(state->num_connector,
sizeof(*state->connector_states),
GFP_KERNEL);
if (!state->connector_states)
@ -117,7 +119,7 @@ void drm_atomic_state_clear(struct drm_atomic_state *state)
DRM_DEBUG_KMS("Clearing atomic state %p\n", state);
for (i = 0; i < config->num_connector; i++) {
for (i = 0; i < state->num_connector; i++) {
struct drm_connector *connector = state->connectors[i];
if (!connector)
@ -304,6 +306,21 @@ drm_atomic_get_connector_state(struct drm_atomic_state *state,
index = drm_connector_index(connector);
/*
* Construction of atomic state updates can race with a connector
* hot-add which might overflow. In this case flip the table and just
* restart the entire ioctl - no one is fast enough to livelock a cpu
* with physical hotplug events anyway.
*
* Note that we only grab the indexes once we have the right lock to
* prevent hotplug/unplugging of connectors. So removal is no problem,
* at most the array is a bit too large.
*/
if (index >= state->num_connector) {
DRM_DEBUG_KMS("Hot-added connector would overflow state array, restarting\n");
return -EAGAIN;
}
if (state->connector_states[index])
return state->connector_states[index];
@ -499,10 +516,9 @@ int
drm_atomic_connectors_for_crtc(struct drm_atomic_state *state,
struct drm_crtc *crtc)
{
int nconnectors = state->dev->mode_config.num_connector;
int i, num_connected_connectors = 0;
for (i = 0; i < nconnectors; i++) {
for (i = 0; i < state->num_connector; i++) {
struct drm_connector_state *conn_state;
conn_state = state->connector_states[i];

23
drivers/gpu/drm/drm_atomic_helper.c
View File

@ -249,7 +249,6 @@ static int
mode_fixup(struct drm_atomic_state *state)
{
int ncrtcs = state->dev->mode_config.num_crtc;
int nconnectors = state->dev->mode_config.num_connector;
struct drm_crtc_state *crtc_state;
struct drm_connector_state *conn_state;
int i;
@ -264,7 +263,7 @@ mode_fixup(struct drm_atomic_state *state)
drm_mode_copy(&crtc_state->adjusted_mode, &crtc_state->mode);
}
for (i = 0; i < nconnectors; i++) {
for (i = 0; i < state->num_connector; i++) {
struct drm_encoder_helper_funcs *funcs;
struct drm_encoder *encoder;
@ -336,7 +335,6 @@ drm_atomic_helper_check_prepare(struct drm_device *dev,
struct drm_atomic_state *state)
{
int ncrtcs = dev->mode_config.num_crtc;
int nconnectors = dev->mode_config.num_connector;
struct drm_crtc *crtc;
struct drm_crtc_state *crtc_state;
int i, ret;
@ -361,7 +359,7 @@ drm_atomic_helper_check_prepare(struct drm_device *dev,
}
}
for (i = 0; i < nconnectors; i++) {
for (i = 0; i < state->num_connector; i++) {
/*
* This only sets crtc->mode_changed for routing changes,
* drivers must set crtc->mode_changed themselves when connector
@ -485,10 +483,9 @@ static void
disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
{
int ncrtcs = old_state->dev->mode_config.num_crtc;
int nconnectors = old_state->dev->mode_config.num_connector;
int i;
for (i = 0; i < nconnectors; i++) {
for (i = 0; i < old_state->num_connector; i++) {
struct drm_connector_state *old_conn_state;
struct drm_connector *connector;
struct drm_encoder_helper_funcs *funcs;
@ -553,12 +550,11 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
static void
set_routing_links(struct drm_device *dev, struct drm_atomic_state *old_state)
{
int nconnectors = dev->mode_config.num_connector;
int ncrtcs = old_state->dev->mode_config.num_crtc;
int i;
/* clear out existing links */
for (i = 0; i < nconnectors; i++) {
for (i = 0; i < old_state->num_connector; i++) {
struct drm_connector *connector;
connector = old_state->connectors[i];
@ -573,7 +569,7 @@ set_routing_links(struct drm_device *dev, struct drm_atomic_state *old_state)
}
/* set new links */
for (i = 0; i < nconnectors; i++) {
for (i = 0; i < old_state->num_connector; i++) {
struct drm_connector *connector;
connector = old_state->connectors[i];
@ -608,7 +604,6 @@ static void
crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *old_state)
{
int ncrtcs = old_state->dev->mode_config.num_crtc;
int nconnectors = old_state->dev->mode_config.num_connector;
int i;
for (i = 0; i < ncrtcs; i++) {
@ -626,7 +621,7 @@ crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *old_state)
funcs->mode_set_nofb(crtc);
}
for (i = 0; i < nconnectors; i++) {
for (i = 0; i < old_state->num_connector; i++) {
struct drm_connector *connector;
struct drm_crtc_state *new_crtc_state;
struct drm_encoder_helper_funcs *funcs;
@ -687,7 +682,6 @@ void drm_atomic_helper_commit_post_planes(struct drm_device *dev,
struct drm_atomic_state *old_state)
{
int ncrtcs = old_state->dev->mode_config.num_crtc;
int nconnectors = old_state->dev->mode_config.num_connector;
int i;
for (i = 0; i < ncrtcs; i++) {
@ -706,7 +700,7 @@ void drm_atomic_helper_commit_post_planes(struct drm_device *dev,
funcs->commit(crtc);
}
for (i = 0; i < nconnectors; i++) {
for (i = 0; i < old_state->num_connector; i++) {
struct drm_connector *connector;
struct drm_encoder_helper_funcs *funcs;
struct drm_encoder *encoder;
@ -1304,7 +1298,6 @@ static int update_output_state(struct drm_atomic_state *state,
{
struct drm_device *dev = set->crtc->dev;
struct drm_connector_state *conn_state;
int nconnectors = state->dev->mode_config.num_connector;
int ncrtcs = state->dev->mode_config.num_crtc;
int ret, i, j;
@ -1333,7 +1326,7 @@ static int update_output_state(struct drm_atomic_state *state,
}
/* Then recompute connector->crtc links and crtc enabling state. */
for (i = 0; i < nconnectors; i++) {
for (i = 0; i < state->num_connector; i++) {
struct drm_connector *connector;
connector = state->connectors[i];

2
include/drm/drm_crtc.h
View File

@ -825,6 +825,7 @@ struct drm_bridge {
* @plane_states: pointer to array of plane states pointers
* @crtcs: pointer to array of CRTC pointers
* @crtc_states: pointer to array of CRTC states pointers
* @num_connector: size of the @connectors and @connector_states arrays
* @connectors: pointer to array of connector pointers
* @connector_states: pointer to array of connector states pointers
* @acquire_ctx: acquire context for this atomic modeset state update
@ -836,6 +837,7 @@ struct drm_atomic_state {
struct drm_plane_state **plane_states;
struct drm_crtc **crtcs;
struct drm_crtc_state **crtc_states;
int num_connector;
struct drm_connector **connectors;
struct drm_connector_state **connector_states;