From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7E492C43458 for ; Tue, 30 Jun 2026 15:25:18 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 16F3110E206; Tue, 30 Jun 2026 15:25:18 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="XlliwJGQ"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4959110E206 for ; Tue, 30 Jun 2026 15:25:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1782833116; x=1814369116; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=V9TI0hFErY4Qy3TtAwY02Ay14Kbdm2ZoGGdNH9kgIyE=; b=XlliwJGQ4tm9uQb6XWjOlAzO/xdCIZ005GdSLE91TKnHFPE5560E8ULL aNaP5QiqnKPUtw2k13mf4g+GEnWdMakfvQRdk0pBJdfvFCFiUdy9bq+4f c8cI7HtWOkYp6sLwZQoxH38d5eZ9I7quQXlPiZedOr9C8yasJMVJQQ+u5 PNRIN8sdtSsNMSmvgFaMkDs2Rhq6wBhbRy/Q4+c34K63f6G5MsaMobok4 pWoSj9YQ3rADw5QzjPGwuSMw66zxVO4mGeeZoCfsV7XTGfLQsSXXOeQ2T Gw8kJ9WbB7w8uCqENfPUXLD4WqaETVH+d1GsuBOvVok1D7+ddwJaDXNEz Q==; X-CSE-ConnectionGUID: 9be8OyCkRF69m7v2mW/wfQ== X-CSE-MsgGUID: hOo/f9fpR6i6mwyLmIzZAQ== X-IronPort-AV: E=McAfee;i="6800,10657,11832"; a="87232658" X-IronPort-AV: E=Sophos;i="6.24,234,1774335600"; d="scan'208";a="87232658" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jun 2026 08:25:16 -0700 X-CSE-ConnectionGUID: Sl4JVyUJShWEpmfm4hlZuQ== X-CSE-MsgGUID: p9Hdq/qRTpOlIt5b9cx2Tw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,234,1774335600"; d="scan'208";a="249661115" Received: from osgc-sh-dragon.sh.intel.com ([10.239.81.44]) by fmviesa008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jun 2026 08:25:14 -0700 From: Jonathan Cavitt To: intel-gfx@lists.freedesktop.org Cc: alex.zuo@intel.com, jonathan.cavitt@intel.com, jani.nikula@linux.intel.com, andi.shyti@intel.com Subject: [PATCH v3] drm/i915/gt: Use poll_timeout_us in place of sliding sleep window Date: Tue, 30 Jun 2026 23:25:11 +0800 Message-ID: <20260630152511.1401029-1-jonathan.cavitt@intel.com> X-Mailer: git-send-email 2.53.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" The functions intel_guc_send_busy_loop and ct_send can theoretically loop forever. In the former case, intel_guc_send_busy_loop can iterate forever if intel_guc_send_nb repeatedly returns -EBUSY. In the latter case, ct_send can loop forever if the guc-to-host or host-to-guc buffers get stuck in a full state. Rework the functions to use the poll_timeout_us family of functions instead of calculating sleep_period_ms repeatedly. In both cases now, if the loop condition is not met after 10 minutes, the function will report it as a failure. This also resolves a static analysis issue involving sleep_period_ms overflowing after several shift-left-logical calls. v2: - Reduce default sleep/udelay duration (jcavitt) v3: - Use atomic in ct_send (jcavitt) Suggested-by: Jani Nikula Signed-off-by: Jonathan Cavitt Cc: Andi Shyti --- drivers/gpu/drm/i915/gt/uc/intel_guc.h | 32 +++++++++++------------ drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 19 +++++--------- 2 files changed, 23 insertions(+), 28 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h index 053780f562c1..13be4f7e7ab7 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h @@ -7,6 +7,7 @@ #define _INTEL_GUC_H_ #include +#include #include #include @@ -360,8 +361,7 @@ static inline int intel_guc_send_busy_loop(struct intel_guc *guc, u32 g2h_len_dw, bool loop) { - int err; - unsigned int sleep_period_ms = 1; + int err, timedout; bool not_atomic = !in_atomic() && !irqs_disabled(); /* @@ -374,20 +374,20 @@ static inline int intel_guc_send_busy_loop(struct intel_guc *guc, /* No sleeping with spin locks, just busy loop */ might_sleep_if(loop && not_atomic); -retry: - err = intel_guc_send_nb(guc, action, len, g2h_len_dw); - if (unlikely(err == -EBUSY && loop)) { - if (likely(not_atomic)) { - if (msleep_interruptible(sleep_period_ms)) - return -EINTR; - sleep_period_ms = sleep_period_ms << 1; - } else { - cpu_relax(); - } - goto retry; - } - - return err; + if (!loop) + return intel_guc_send_nb(guc, action, len, g2h_len_dw); + + if (not_atomic) + timedout = poll_timeout_us(err = intel_guc_send_nb(guc, action, + len, g2h_len_dw), + err != -EBUSY, USEC_PER_MSEC, + 600 * USEC_PER_SEC, false); + else + timedout = poll_timeout_us_atomic(err = intel_guc_send_nb(guc, action, + len, g2h_len_dw), + err != -EBUSY, USEC_PER_MSEC, + 600 * USEC_PER_SEC, false); + return timedout ?: err; } /* Only call this from the interrupt handler code */ diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c index 1c455d84bf9d..dc4a5486b42c 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c @@ -716,7 +716,6 @@ static int ct_send(struct intel_guc_ct *ct, struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; struct ct_request request; unsigned long flags; - unsigned int sleep_period_ms = 1; bool send_again; u32 fence; int err; @@ -736,22 +735,18 @@ static int ct_send(struct intel_guc_ct *ct, * rare. Reserving the maximum size in the G2H credits as we don't know * how big the response is going to be. */ -retry: spin_lock_irqsave(&ctb->lock, flags); - if (unlikely(!h2g_has_room(ct, len + GUC_CTB_HDR_LEN) || - !g2h_has_room(ct, GUC_CTB_HXG_MSG_MAX_LEN))) { + err = poll_timeout_us_atomic(err = 0, + !h2g_has_room(ct, len + GUC_CTB_HDR_LEN) || + !g2h_has_room(ct, GUC_CTB_HXG_MSG_MAX_LEN), + USEC_PER_MSEC, 600 * USEC_PER_SEC, false); + + if (err) { if (ct->stall_time == KTIME_MAX) ct->stall_time = ktime_get(); spin_unlock_irqrestore(&ctb->lock, flags); - if (unlikely(ct_deadlocked(ct))) - return -EPIPE; - - if (msleep_interruptible(sleep_period_ms)) - return -EINTR; - sleep_period_ms = sleep_period_ms << 1; - - goto retry; + return unlikely(ct_deadlocked(ct)) ? -EPIPE : err; } ct->stall_time = KTIME_MAX; -- 2.53.0