From b5179dbd1c14743ae80f0aaa28eaaf35c361608f Mon Sep 17 00:00:00 2001 From: Jonathan Cavitt Date: Mon, 22 Dec 2025 20:19:59 +0000 Subject: [PATCH] drm/xe/guc: READ/WRITE_ONCE g2h_fence->done Use READ_ONCE and WRITE_ONCE when operating on g2h_fence->done to prevent the compiler from ignoring important modifications to its value. Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs") Suggested-by: Matthew Brost Signed-off-by: Jonathan Cavitt Cc: Rodrigo Vivi Reviewed-by: Matthew Brost Link: https://patch.msgid.link/20251222201957.63245-5-jonathan.cavitt@intel.com Signed-off-by: Rodrigo Vivi --- drivers/gpu/drm/xe/xe_guc_ct.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c index c3df9b3f1b4d..f2148a8bf208 100644 --- a/drivers/gpu/drm/xe/xe_guc_ct.c +++ b/drivers/gpu/drm/xe/xe_guc_ct.c @@ -206,7 +206,9 @@ static void g2h_fence_cancel(struct g2h_fence *g2h_fence) { g2h_fence->cancel = true; g2h_fence->fail = true; - g2h_fence->done = true; + + /* WRITE_ONCE pairs with READ_ONCEs in guc_ct_send_recv. */ + WRITE_ONCE(g2h_fence->done, true); } static bool g2h_fence_needs_alloc(struct g2h_fence *g2h_fence) @@ -1294,10 +1296,13 @@ retry_same_fence: return ret; } - ret = wait_event_timeout(ct->g2h_fence_wq, g2h_fence.done, HZ); + /* READ_ONCEs pairs with WRITE_ONCEs in parse_g2h_response + * and g2h_fence_cancel. + */ + ret = wait_event_timeout(ct->g2h_fence_wq, READ_ONCE(g2h_fence.done), HZ); if (!ret) { LNL_FLUSH_WORK(&ct->g2h_worker); - if (g2h_fence.done) { + if (READ_ONCE(g2h_fence.done)) { xe_gt_warn(gt, "G2H fence %u, action %04x, done\n", g2h_fence.seqno, action[0]); ret = 1; @@ -1498,7 +1503,8 @@ static int parse_g2h_response(struct xe_guc_ct *ct, u32 *msg, u32 len) g2h_release_space(ct, GUC_CTB_HXG_MSG_MAX_LEN); - g2h_fence->done = true; + /* WRITE_ONCE pairs with READ_ONCEs in guc_ct_send_recv. */ + WRITE_ONCE(g2h_fence->done, true); smp_mb(); wake_up_all(&ct->g2h_fence_wq); -- 2.47.3