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 F40C4111BF; Wed, 4 Jun 2025 00:52:48 +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=1748998369; cv=none; b=YbloY+r1Qc7MwErWdG1YtAN1N/sIYnv8vJBfnHbzDR41rp41JlmlozQZuVpjFe+VK2s4YWIXYQjis1wEMNx0Srdx3kwf0syYAabzrhtuWqvp4mXfDdTXI/0hfoYglbiMdiXFnDILv3ikU51qKRjE7/wFf+0tFdpX4MpN2GjWsac= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748998369; c=relaxed/simple; bh=WqTxG+GTFwkX5t72aDNMBFs7Y7N43jDTPU21dIgUKMg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=Rux/omU1r/RStwpSqi23InhM2mkHOgn7G9DzotSWbsh1jmuyl5xvjkz2HlIPRGQ0OGtvYxLNXgbzycc2YJEmNlQK5AOtpM1LsG3qmtOPeemtTnewuqULGMgs1JEnqd4hVAGEuWC+0AJQhiiHCCrYb0M9uVuh5f0Y1GWeV7grqnQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=J8TJvwNv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="J8TJvwNv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8933C4CEED; Wed, 4 Jun 2025 00:52:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1748998368; bh=WqTxG+GTFwkX5t72aDNMBFs7Y7N43jDTPU21dIgUKMg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=J8TJvwNvqN27N9FqUeC/eFXZ27xmPQsypx1toBLhrKZvxnGd7IhDpGBATq6Ba8bAw eIfIzjN4ViVuD5RoivoR0kn/QPb1DOQhFIDpvy139PMXDIeohefoBzyHTO+NHHB7BX Tbpz1jTVZdv015ZldmxZOQJKK2vUJc223x+X5fUGGaaXXm1CjpeSHCBEThGcgieVvw cd02e8ZTVo8hLSXNfKOfdFLvuU4y822XcaJbt5mlo3E2dWb4XjqJhXuIaGYBs2YLMP HyrQAOJ1/mas25EujRJgdgW+2PKmwb30C3i0VitZ8WNHirmxXs3igi8BnqFAWElX6q HzTS9GVMbVozw== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Jason Xing , Tariq Toukan , Jakub Kicinski , Sasha Levin , netdev@vger.kernel.org, linux-rdma@vger.kernel.org Subject: [PATCH AUTOSEL 6.15 054/118] net: mlx4: add SOF_TIMESTAMPING_TX_SOFTWARE flag when getting ts info Date: Tue, 3 Jun 2025 20:49:45 -0400 Message-Id: <20250604005049.4147522-54-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250604005049.4147522-1-sashal@kernel.org> References: <20250604005049.4147522-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.15 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Jason Xing [ Upstream commit b86bcfee30576b752302c55693fff97242b35dfd ] As mlx4 has implemented skb_tx_timestamp() in mlx4_en_xmit(), the SOFTWARE flag is surely needed when users are trying to get timestamp information. Signed-off-by: Jason Xing Reviewed-by: Tariq Toukan Link: https://patch.msgid.link/20250510093442.79711-1-kerneljasonxing@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- Perfect! Now I can see that `skb_tx_timestamp(skb)` is called in the `mlx4_en_xmit()` function, which is the main transmit function. This confirms that the mlx4 driver does implement software timestamping. Now let me compare this to the similar commits to see the pattern: **YES** This commit should be backported to stable kernel trees. **Extensive Explanation:** This commit addresses a clear inconsistency bug where the mlx4 driver implements software timestamping functionality but fails to advertise this capability to userspace through the ethtool timestamping info interface. **Analysis of the fix:** 1. **The Problem**: The mlx4 driver calls `skb_tx_timestamp(skb)` in `mlx4_en_xmit()` at line 1091 of `/drivers/net/ethernet/mellanox/mlx4/en_tx.c`, which means it properly implements software TX timestamping. However, in `mlx4_en_get_ts_info()`, it only advertises hardware timestamping capabilities (`SOF_TIMESTAMPING_TX_HARDWARE`, `SOF_TIMESTAMPING_RX_HARDWARE`, `SOF_TIMESTAMPING_RAW_HARDWARE`) but omits the `SOF_TIMESTAMPING_TX_SOFTWARE` flag. 2. **The Fix**: The change adds a single line `SOF_TIMESTAMPING_TX_SOFTWARE |` to the `info->so_timestamping` field when hardware timestamping is supported, correctly advertising both hardware and software timestamping capabilities. 3. **Impact**: This is a user-facing API correctness issue. Applications checking timestamping capabilities via ethtool would incorrectly believe software timestamping is not supported, even though the driver implements it. **Comparison with similar commits:** - **Similar Commit #1 (YES)**: Also fixed a timestamping bug in mlx4, showing these are important fixes - **Similar Commit #3 (YES)**: Fixed incorrect timestamping capability reporting in mlx5 by removing false software timestamping indication - **Similar Commit #5 (YES)**: Fixed timestamping capabilities reporting using wrong BIT() macro in mlx5 The pattern shows that timestamping capability reporting bugs are consistently considered backport-worthy because they affect user-visible API behavior. **Backport Criteria Assessment:** ✅ **Fixes a user- affecting bug**: Applications cannot detect software timestamping support ✅ **Small, contained change**: Single line addition with no functional logic changes ✅ **No architectural changes**: Only fixes capability reporting ✅ **Low regression risk**: Only adds a missing flag, doesn't change driver behavior ✅ **Clear side effects**: None beyond correctly advertising existing functionality ✅ **Follows stable rules**: Important API correctness fix with minimal risk The fix is identical in nature to Similar Commit #3 (marked YES) but in reverse - where mlx5 removed false software timestamping advertisement, this adds the missing software timestamping advertisement for mlx4 where it's actually implemented. drivers/net/ethernet/mellanox/mlx4/en_ethtool.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c index cd17a3f4faf83..a68cd3f0304c6 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c @@ -1897,6 +1897,7 @@ static int mlx4_en_get_ts_info(struct net_device *dev, if (mdev->dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_TS) { info->so_timestamping |= SOF_TIMESTAMPING_TX_HARDWARE | + SOF_TIMESTAMPING_TX_SOFTWARE | SOF_TIMESTAMPING_RX_HARDWARE | SOF_TIMESTAMPING_RAW_HARDWARE; -- 2.39.5