From a464bace0482aa9a83e9aa7beefbaf44cd58e6cf Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Fri, 13 Mar 2026 13:07:40 +0200 Subject: [PATCH] drm/i915: Order OP vs. timeout correctly in __wait_for() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Put the barrier() before the OP so that anything we read out in OP and check in COND will actually be read out after the timeout has been evaluated. Currently the only place where we use OP is __intel_wait_for_register(), but the use there is precisely susceptible to this reordering, assuming the ktime_*() stuff itself doesn't act as a sufficient barrier: __intel_wait_for_register(...) { ... ret = __wait_for(reg_value = intel_uncore_read_notrace(...), (reg_value & mask) == value, ...); ... } Cc: stable@vger.kernel.org Fixes: 1c3c1dc66a96 ("drm/i915: Add compiler barrier to wait_for") Signed-off-by: Ville Syrjälä Link: https://patch.msgid.link/20260313110740.24620-1-ville.syrjala@linux.intel.com Reviewed-by: Jani Nikula --- drivers/gpu/drm/i915/i915_wait_util.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_wait_util.h b/drivers/gpu/drm/i915/i915_wait_util.h index 7376898e3bf83..e1ed7921ec701 100644 --- a/drivers/gpu/drm/i915/i915_wait_util.h +++ b/drivers/gpu/drm/i915/i915_wait_util.h @@ -25,9 +25,9 @@ might_sleep(); \ for (;;) { \ const bool expired__ = ktime_after(ktime_get_raw(), end__); \ - OP; \ /* Guarantee COND check prior to timeout */ \ barrier(); \ + OP; \ if (COND) { \ ret__ = 0; \ break; \ -- 2.47.3