From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 00384362135; Tue, 6 Jan 2026 17:50:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767721827; cv=none; b=O3tHcj4tPBhymnYpfCbLaKAt+T2GYCUzpPTUPmAAdGdrvB8ifcKw7H0nKBC1rhc1W+wz88rOMtfj985mlTDEjqGBN43ulKzppkVA+8LGpUgYjy4goI6k9D3mOeT1CifQASvKWixFzTkpw2ecBGBqSTbqL2mZ1LJNLhOIfOZbhQE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767721827; c=relaxed/simple; bh=tfjizciqjTAEvxTLmCaOOzjgmfsYHBU+rbAvFpJIj00=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=TJPd2/EAjRKcRHBAl6u2LJ5GM6WazQt/tc7KN7yOhdKaFg04DjXsr2TlQrW4MsoDoDlLxc+4OfAg0QiN9QIQK4EzzgEF57GiOrdE0+nGT63sR7Fikz2jMlsIWIAqpcLAr9/01Ak6UN4YO8jADIXwR44f+pIxRk9xgfFn7vezkqk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=itIpT2KU; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="itIpT2KU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61CAFC116C6; Tue, 6 Jan 2026 17:50:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767721826; bh=tfjizciqjTAEvxTLmCaOOzjgmfsYHBU+rbAvFpJIj00=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=itIpT2KUC+tssSbYoiTvjz/KR8UnJtVrlfnM6n6EnUTB1GAuKoZ5CQyA7rcp3pGa0 7ufxTIXbECFL8NenT2c3cvzBpGYLq70wyjCUXmLpi5dCQBnSkFfopQTT5UsqhZJaoD iGcH8UvZarRSjsJAqGKnDuCKP50yfiwitW047nxE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Matthew Brost , Jonathan Cavitt , Rodrigo Vivi , =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= , Sasha Levin Subject: [PATCH 6.18 082/312] drm/xe/guc: READ/WRITE_ONCE g2h_fence->done Date: Tue, 6 Jan 2026 18:02:36 +0100 Message-ID: <20260106170550.804665535@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260106170547.832845344@linuxfoundation.org> References: <20260106170547.832845344@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jonathan Cavitt [ 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 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 (cherry picked from commit b5179dbd1c14743ae80f0aaa28eaaf35c361608f) Signed-off-by: Thomas Hellström Signed-off-by: Sasha Levin --- 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); -- 2.51.0