From 86de88cfeb7cf33c7bbd18360e041c7d4e651bba Mon Sep 17 00:00:00 2001 From: Rob Clark Date: Mon, 4 Nov 2019 09:37:36 -0800 Subject: [PATCH] drm/atomic: fix self-refresh helpers crtc state dereference drm_self_refresh_helper_update_avg_times() was incorrectly accessing the new incoming state after drm_atomic_helper_commit_hw_done(). But this state might have already been superceeded by an !nonblock atomic update resulting in dereferencing an already free'd crtc_state. TODO I *think* this will more or less do the right thing.. althought I'm not 100% sure if, for example, we enter psr in a nonblock commit, and then leave psr in a !nonblock commit that overtakes the completion of the nonblock commit. Not sure if this sort of scenario can happen in practice. But not crashing is better than crashing, so I guess we should either take this patch or rever the self-refresh helpers until Sean can figure out a better solution. Fixes: d4da4e33341c ("drm: Measure Self Refresh Entry/Exit times to avoid thrashing") Cc: Sean Paul Signed-off-by: Rob Clark [seanpaul fixed up some checkpatch warns] Signed-off-by: Sean Paul Link: https://patchwork.freedesktop.org/patch/msgid/20191104173737.142558-1-robdclark@gmail.com --- drivers/gpu/drm/drm_atomic_helper.c | 15 ++++++++++++++- drivers/gpu/drm/drm_self_refresh_helper.c | 18 +++++++++++------- include/drm/drm_self_refresh_helper.h | 3 ++- 3 files changed, 27 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 3ef2ac5..2dd2cd8 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1581,8 +1581,11 @@ static void commit_tail(struct drm_atomic_state *old_state) { struct drm_device *dev = old_state->dev; const struct drm_mode_config_helper_funcs *funcs; + struct drm_crtc_state *new_crtc_state; + struct drm_crtc *crtc; ktime_t start; s64 commit_time_ms; + unsigned int i, new_self_refresh_mask = 0; funcs = dev->mode_config.helper_private; @@ -1602,6 +1605,15 @@ static void commit_tail(struct drm_atomic_state *old_state) drm_atomic_helper_wait_for_dependencies(old_state); + /* + * We cannot safely access new_crtc_state after + * drm_atomic_helper_commit_hw_done() so figure out which crtc's have + * self-refresh active beforehand: + */ + for_each_new_crtc_in_state(old_state, crtc, new_crtc_state, i) + if (new_crtc_state->self_refresh_active) + new_self_refresh_mask |= BIT(i); + if (funcs && funcs->atomic_commit_tail) funcs->atomic_commit_tail(old_state); else @@ -1610,7 +1622,8 @@ static void commit_tail(struct drm_atomic_state *old_state) commit_time_ms = ktime_ms_delta(ktime_get(), start); if (commit_time_ms > 0) drm_self_refresh_helper_update_avg_times(old_state, - (unsigned long)commit_time_ms); + (unsigned long)commit_time_ms, + new_self_refresh_mask); drm_atomic_helper_commit_cleanup_done(old_state); diff --git a/drivers/gpu/drm/drm_self_refresh_helper.c b/drivers/gpu/drm/drm_self_refresh_helper.c index 68f4765..dd33fec 100644 --- a/drivers/gpu/drm/drm_self_refresh_helper.c +++ b/drivers/gpu/drm/drm_self_refresh_helper.c @@ -133,29 +133,33 @@ out_drop_locks: * drm_self_refresh_helper_update_avg_times - Updates a crtc's SR time averages * @state: the state which has just been applied to hardware * @commit_time_ms: the amount of time in ms that this commit took to complete + * @new_self_refresh_mask: bitmask of crtc's that have self_refresh_active in + * new state * * Called after &drm_mode_config_funcs.atomic_commit_tail, this function will * update the average entry/exit self refresh times on self refresh transitions. * These averages will be used when calculating how long to delay before * entering self refresh mode after activity. */ -void drm_self_refresh_helper_update_avg_times(struct drm_atomic_state *state, - unsigned int commit_time_ms) +void +drm_self_refresh_helper_update_avg_times(struct drm_atomic_state *state, + unsigned int commit_time_ms, + unsigned int new_self_refresh_mask) { struct drm_crtc *crtc; - struct drm_crtc_state *old_crtc_state, *new_crtc_state; + struct drm_crtc_state *old_crtc_state; int i; - for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, - new_crtc_state, i) { + for_each_old_crtc_in_state(state, crtc, old_crtc_state, i) { + bool new_self_refresh_active = new_self_refresh_mask & BIT(i); struct drm_self_refresh_data *sr_data = crtc->self_refresh_data; struct ewma_psr_time *time; if (old_crtc_state->self_refresh_active == - new_crtc_state->self_refresh_active) + new_self_refresh_active) continue; - if (new_crtc_state->self_refresh_active) + if (new_self_refresh_active) time = &sr_data->entry_avg_ms; else time = &sr_data->exit_avg_ms; diff --git a/include/drm/drm_self_refresh_helper.h b/include/drm/drm_self_refresh_helper.h index 5b79d25..520235c 100644 --- a/include/drm/drm_self_refresh_helper.h +++ b/include/drm/drm_self_refresh_helper.h @@ -13,7 +13,8 @@ struct drm_crtc; void drm_self_refresh_helper_alter_state(struct drm_atomic_state *state); void drm_self_refresh_helper_update_avg_times(struct drm_atomic_state *state, - unsigned int commit_time_ms); + unsigned int commit_time_ms, + unsigned int new_self_refresh_mask); int drm_self_refresh_helper_init(struct drm_crtc *crtc); void drm_self_refresh_helper_cleanup(struct drm_crtc *crtc); -- 2.7.4