6.18-stable review patch. If anyone has any objections, please let me know.
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From: Jonathan Cavitt jonathan.cavitt@intel.com
[ Upstream commit bed2a6bd20681aacfb063015c1edfab6f58a333e ]
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 matthew.brost@intel.com Signed-off-by: Jonathan Cavitt jonathan.cavitt@intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Reviewed-by: Matthew Brost matthew.brost@intel.com Link: https://patch.msgid.link/20251222201957.63245-5-jonathan.cavitt@intel.com Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com (cherry picked from commit b5179dbd1c14743ae80f0aaa28eaaf35c361608f) Signed-off-by: Thomas Hellström thomas.hellstrom@linux.intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 b7afe8e983cb..3aac1a7aa2e7 100644 --- a/drivers/gpu/drm/xe/xe_guc_ct.c +++ b/drivers/gpu/drm/xe/xe_guc_ct.c @@ -106,7 +106,9 @@ 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) @@ -1128,10 +1130,13 @@ static int guc_ct_send_recv(struct xe_guc_ct *ct, const u32 *action, u32 len, 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; @@ -1375,7 +1380,8 @@ 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);