From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (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 40E7540BCC3; Mon, 8 Jun 2026 15:01:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780930883; cv=none; b=q7jqIN93AGZGnrQv41kaETHAyu+bOHUlQ2ErDtcZyfLGLr35J5My9j6Yz+lYEOm3dEhAbFzgAnY8eCJA/q9GIL0rPrh/TGXaqMuQHLtiD2x7lKJSh9HsmgIQLtKS8lkAti+DAwRqLVwVc+FbxWtAArl2mFBW9vf163YBz+AB4QY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780930883; c=relaxed/simple; bh=NKP9ir8/NAmHYlfm0hZw49b1a56R0gaCRSmdEw7uKwM=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=D/MLVlNk6ehO1yB38RTZ5+KuXnbMBfwgP9vXtCqmU1S0Q7qbC40Xbd8eQAnUa2BSvQDFTdJYIb26hBGoW8duXKM/mWnw1ZrPMi8aCzLfLaVlrgQ/10NG2kMP6tsX0qCMoPqD7S508uBB9qqAdb3OACCmbQU/E0WKAC3gXVT7QmU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=kc57xW//; arc=none smtp.client-ip=148.251.105.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="kc57xW//" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1780930876; bh=NKP9ir8/NAmHYlfm0hZw49b1a56R0gaCRSmdEw7uKwM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=kc57xW//jOAjV5tuRDn8U8tFSaYIM/zTPEsaCHQ1C3AU+FLwTjmyr3XOaQYVykrwX DSkKGxc2MNi51e/UOzHxzEcVPrjHst0e4OQidxoRkkyjbGil4EZJ4GS92ouGk1VEu1 HX7iqzNvIKrmRTfKcDmQjGuYlfxGpsfMj7Jgkuld5IeC/Lt6gOUw7Gr9guTWeRUGK9 jq/VUR/3dLlfmG3TIwORPR2pFMWacfCXh0Q9t9So/8BkHrR0OQ2v7/Udx2v0ODQlaK A73AhGvOLzf+kN5ctc7qOdgACC4E9Oh1lKou7/lgOSg6D6QRFwcfX09izXpdzQH8IZ W6fCzm2dRf/yQ== Received: from fedora-2.home (unknown [100.64.0.11]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id D66CB17E0979; Mon, 8 Jun 2026 17:01:15 +0200 (CEST) Date: Mon, 8 Jun 2026 17:01:12 +0200 From: Boris Brezillon To: Philipp Stanner Cc: Sumit Semwal , Christian =?UTF-8?B?S8O2bmln?= , Alice Ryhl , Daniel Almeida , Gary Guo , Tvrtko Ursulin , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Danilo Krummrich Subject: Re: [RFC PATCH] dma-fence: Fix races of fence callbacks versus destructors by locking Message-ID: <20260608170112.24fd92df@fedora-2.home> In-Reply-To: <20260608142436.265820-2-phasta@kernel.org> References: <20260608142436.265820-2-phasta@kernel.org> Organization: Collabora X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 8 Jun 2026 16:24:37 +0200 Philipp Stanner wrote: > @@ -1020,11 +1024,20 @@ EXPORT_SYMBOL(dma_fence_wait_any_timeout); > void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline) > { > const struct dma_fence_ops *ops; > + unsigned long flags; > > rcu_read_lock(); > ops = rcu_dereference(fence->ops); > - if (ops && ops->set_deadline && !dma_fence_is_signaled(fence)) > + if (!ops || !ops->set_deadline) { > + rcu_read_unlock(); > + return; > + } > + > + dma_fence_lock_irqsave(fence, flags); > + if (!dma_fence_is_signaled_locked(fence)) > ops->set_deadline(fence, deadline); You can't take the fence lock around ->set_deadline(), otherwise you'll deadlock here [1] or here [2]. > + > + dma_fence_unlock_irqrestore(fence, flags); > rcu_read_unlock(); > } [1]https://elixir.bootlin.com/linux/v7.0.11/source/drivers/dma-buf/sw_sync.c#L182 [2]https://elixir.bootlin.com/linux/v7.0.11/source/drivers/gpu/drm/msm/msm_fence.c#L139