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 6E02E223E61; Thu, 12 Dec 2024 17:48:30 +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=1734025710; cv=none; b=leBy4z/MGPZqVC1EBKBZXGOQ2dY17JErPatF3fRT5wJ2S4rAthswQdFjqEiFXuCE4Gbw13lXbWUF924P2Ba4ub9aoKEvVPT7VKdKe3EInTDeUWJMaPW2NC5/10et0KBROHaf2xh8QzwwIiXFgpdoZK91MbXThE9oY82g+dDgNf4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734025710; c=relaxed/simple; bh=O+4CZVjelUAfKmISBHoTH1jtwS7jhLBF7n6zz+q1tfQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=O2U7xWBfxWCMcWnIEcrj3mMr4eLeNJDel0UktFz9B7zXt5TVYYQXML1IhlCK4JZLq3ea5Whk1FT5ptjRts9Hmpf4a81MG6U09+yPT/gEmR/rEXuNTBgyYs0ecTznCHAGVhLJWC7IK9YvSZEt7DaqkjpASzLFcOzGdUObWCmaR8o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mERhfPok; 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="mERhfPok" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8074C4CED1; Thu, 12 Dec 2024 17:48:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734025710; bh=O+4CZVjelUAfKmISBHoTH1jtwS7jhLBF7n6zz+q1tfQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mERhfPokgdvpQxSpY37g58us2/ynmGkVdVir4iAqSinC/cBPS9fd5s/etcB6VUiuG yIOmnMwMxZFFz3mOFPTEYVa2jZwqL+CgP1ZW5ly7yMWnXuyPY5Q7pAwp5foI0ZU/y5 G6NsHlKC8w11SUo56DT6ZqWIamNZnQQnfZofGiKY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Christian=20K=C3=B6nig?= , Boris Brezillon , Chia-I Wu , Tvrtko Ursulin Subject: [PATCH 5.4 261/321] dma-buf: fix dma_fence_array_signaled v4 Date: Thu, 12 Dec 2024 16:02:59 +0100 Message-ID: <20241212144240.292701874@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241212144229.291682835@linuxfoundation.org> References: <20241212144229.291682835@linuxfoundation.org> User-Agent: quilt/0.67 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 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christian König commit 78ac1c3558810486d90aa533b0039aa70487a3da upstream. The function silently assumed that signaling was already enabled for the dma_fence_array. This meant that without enabling signaling first we would never see forward progress. Fix that by falling back to testing each individual fence when signaling isn't enabled yet. v2: add the comment suggested by Boris why this is done this way v3: fix the underflow pointed out by Tvrtko v4: atomic_read_acquire() as suggested by Tvrtko Signed-off-by: Christian König Reviewed-by: Boris Brezillon Tested-by: Chia-I Wu Reviewed-by: Tvrtko Ursulin Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/12094 Cc: Link: https://patchwork.freedesktop.org/patch/msgid/20241112121925.18464-1-christian.koenig@amd.com Signed-off-by: Greg Kroah-Hartman --- drivers/dma-buf/dma-fence-array.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) --- a/drivers/dma-buf/dma-fence-array.c +++ b/drivers/dma-buf/dma-fence-array.c @@ -103,10 +103,36 @@ static bool dma_fence_array_enable_signa static bool dma_fence_array_signaled(struct dma_fence *fence) { struct dma_fence_array *array = to_dma_fence_array(fence); + int num_pending; + unsigned int i; - if (atomic_read(&array->num_pending) > 0) + /* + * We need to read num_pending before checking the enable_signal bit + * to avoid racing with the enable_signaling() implementation, which + * might decrement the counter, and cause a partial check. + * atomic_read_acquire() pairs with atomic_dec_and_test() in + * dma_fence_array_enable_signaling() + * + * The !--num_pending check is here to account for the any_signaled case + * if we race with enable_signaling(), that means the !num_pending check + * in the is_signalling_enabled branch might be outdated (num_pending + * might have been decremented), but that's fine. The user will get the + * right value when testing again later. + */ + num_pending = atomic_read_acquire(&array->num_pending); + if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &array->base.flags)) { + if (num_pending <= 0) + goto signal; return false; + } + for (i = 0; i < array->num_fences; ++i) { + if (dma_fence_is_signaled(array->fences[i]) && !--num_pending) + goto signal; + } + return false; + +signal: dma_fence_array_clear_pending_error(array); return true; }