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Tue, 6 Jun 2023 01:33:32 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6600,9927,10732"; a="336887983" X-IronPort-AV: E=Sophos;i="6.00,218,1681196400"; d="scan'208";a="336887983" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Jun 2023 18:33:31 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10732"; a="833020980" X-IronPort-AV: E=Sophos;i="6.00,218,1681196400"; d="scan'208";a="833020980" Received: from unknown (HELO vcostago-mobl3.jf.intel.com) ([10.24.14.106]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Jun 2023 18:33:30 -0700 From: Vinicius Costa Gomes To: intel-wired-lan@lists.osuosl.org Date: Mon, 5 Jun 2023 18:33:22 -0700 Message-Id: <20230606013325.602823-2-vinicius.gomes@intel.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230606013325.602823-1-vinicius.gomes@intel.com> References: <20230606013325.602823-1-vinicius.gomes@intel.com> MIME-Version: 1.0 X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1686015212; x=1717551212; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=JvmwDlkwypyx2zW/dLR5UipqupWXCi+4I5wYyUv5QKw=; b=NaZfNXVmWLVXeyU/jS+QcccltUKMzoWD31sDX9QYQxQCB4vKBe/RUu5m RgCBgPQRxDtsgIqBhs+UlVYrLYE4fsukVMnJk1RT/nttRShj6YeBQ0d6E CG710Oy/b5TrJN00YCFCUqyPw0gFQ7X+3QTbz4uN+xFhMiV5XKBSZjMHx DHNiYWq5d+glJiKlUnWPtFa59hvNq72CsmoXz6k9alnx2EE5njluwlIX+ 1cDYG6uVvx9/U/tBH3OYe6cBNx8GhVoo5gCGrBcZnDx8MjsXvzo7jw0j/ aNnZXGjMwIq1fPuhRJVEKlGMtnstNUl3A01uu3sXkDeusxRbKxbEnaao/ A==; X-Mailman-Original-Authentication-Results: smtp4.osuosl.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=NaZfNXVm Subject: [Intel-wired-lan] [PATCH iwl-net v3 1/4] igc: Fix race condition in PTP tx code X-BeenThere: intel-wired-lan@osuosl.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andre Guedes , vladimir.oltean@nxp.com, kurt@linutronix.de, anthony.l.nguyen@intel.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" Currently, the igc driver supports timestamping only one tx packet at a time. During the transmission flow, the skb that requires hardware timestamping is saved in adapter->ptp_tx_skb. Once hardware has the timestamp, an interrupt is delivered, and adapter->ptp_tx_work is scheduled. In igc_ptp_tx_work(), we read the timestamp register, update adapter->ptp_tx_skb, and notify the network stack. While the thread executing the transmission flow (the user process running in kernel mode) and the thread executing ptp_tx_work don't access adapter->ptp_tx_skb concurrently, there are two other places where adapter->ptp_tx_skb is accessed: igc_ptp_tx_hang() and igc_ptp_suspend(). igc_ptp_tx_hang() is executed by the adapter->watchdog_task worker thread which runs periodically so it is possible we have two threads accessing ptp_tx_skb at the same time. Consider the following scenario: right after __IGC_PTP_TX_IN_PROGRESS is set in igc_xmit_frame_ring(), igc_ptp_tx_hang() is executed. Since adapter->ptp_tx_start hasn't been written yet, this is considered a timeout and adapter->ptp_tx_skb is cleaned up. This patch fixes the issue described above by adding the ptp_tx_lock to protect access to ptp_tx_skb and ptp_tx_start fields from igc_adapter. Since igc_xmit_frame_ring() called in atomic context by the networking stack, ptp_tx_lock is defined as a spinlock, and the irq safe variants of lock/unlock are used. With the introduction of the ptp_tx_lock, the __IGC_PTP_TX_IN_PROGRESS flag doesn't provide much of a use anymore so this patch gets rid of it. Fixes: 2c344ae24501 ("igc: Add support for TX timestamping") Signed-off-by: Andre Guedes Signed-off-by: Vinicius Costa Gomes Reviewed-by: Kurt Kanzenbach --- drivers/net/ethernet/intel/igc/igc.h | 5 +- drivers/net/ethernet/intel/igc/igc_main.c | 9 ++-- drivers/net/ethernet/intel/igc/igc_ptp.c | 61 ++++++++++++----------- 3 files changed, 43 insertions(+), 32 deletions(-) diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h index 34aebf00a512..7da0657ea48f 100644 --- a/drivers/net/ethernet/intel/igc/igc.h +++ b/drivers/net/ethernet/intel/igc/igc.h @@ -229,6 +229,10 @@ struct igc_adapter { struct ptp_clock *ptp_clock; struct ptp_clock_info ptp_caps; struct work_struct ptp_tx_work; + /* Access to ptp_tx_skb and ptp_tx_start are protected by the + * ptp_tx_lock. + */ + spinlock_t ptp_tx_lock; struct sk_buff *ptp_tx_skb; struct hwtstamp_config tstamp_config; unsigned long ptp_tx_start; @@ -401,7 +405,6 @@ enum igc_state_t { __IGC_TESTING, __IGC_RESETTING, __IGC_DOWN, - __IGC_PTP_TX_IN_PROGRESS, }; enum igc_tx_flags { diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index 1c4676882082..a61afa69975e 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -1583,9 +1583,10 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, * the other timer registers before skipping the * timestamping request. */ - if (adapter->tstamp_config.tx_type == HWTSTAMP_TX_ON && - !test_and_set_bit_lock(__IGC_PTP_TX_IN_PROGRESS, - &adapter->state)) { + unsigned long flags; + + spin_lock_irqsave(&adapter->ptp_tx_lock, flags); + if (adapter->tstamp_config.tx_type == HWTSTAMP_TX_ON && !adapter->ptp_tx_skb) { skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS; tx_flags |= IGC_TX_FLAGS_TSTAMP; @@ -1594,6 +1595,8 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, } else { adapter->tx_hwtstamp_skipped++; } + + spin_unlock_irqrestore(&adapter->ptp_tx_lock, flags); } if (skb_vlan_tag_present(skb)) { diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c index 4e10ced736db..56128e55f5c0 100644 --- a/drivers/net/ethernet/intel/igc/igc_ptp.c +++ b/drivers/net/ethernet/intel/igc/igc_ptp.c @@ -603,6 +603,7 @@ static int igc_ptp_set_timestamp_mode(struct igc_adapter *adapter, return 0; } +/* Requires adapter->ptp_tx_lock held by caller. */ static void igc_ptp_tx_timeout(struct igc_adapter *adapter) { struct igc_hw *hw = &adapter->hw; @@ -610,7 +611,6 @@ static void igc_ptp_tx_timeout(struct igc_adapter *adapter) dev_kfree_skb_any(adapter->ptp_tx_skb); adapter->ptp_tx_skb = NULL; adapter->tx_hwtstamp_timeouts++; - clear_bit_unlock(__IGC_PTP_TX_IN_PROGRESS, &adapter->state); /* Clear the tx valid bit in TSYNCTXCTL register to enable interrupt. */ rd32(IGC_TXSTMPH); netdev_warn(adapter->netdev, "Tx timestamp timeout\n"); @@ -618,20 +618,20 @@ static void igc_ptp_tx_timeout(struct igc_adapter *adapter) void igc_ptp_tx_hang(struct igc_adapter *adapter) { - bool timeout = time_is_before_jiffies(adapter->ptp_tx_start + - IGC_PTP_TX_TIMEOUT); - - if (!test_bit(__IGC_PTP_TX_IN_PROGRESS, &adapter->state)) - return; - - /* If we haven't received a timestamp within the timeout, it is - * reasonable to assume that it will never occur, so we can unlock the - * timestamp bit when this occurs. - */ - if (timeout) { - cancel_work_sync(&adapter->ptp_tx_work); - igc_ptp_tx_timeout(adapter); - } + unsigned long flags; + + spin_lock_irqsave(&adapter->ptp_tx_lock, flags); + + if (!adapter->ptp_tx_skb) + goto unlock; + + if (time_is_after_jiffies(adapter->ptp_tx_start + IGC_PTP_TX_TIMEOUT)) + goto unlock; + + igc_ptp_tx_timeout(adapter); + +unlock: + spin_unlock_irqrestore(&adapter->ptp_tx_lock, flags); } /** @@ -641,6 +641,8 @@ void igc_ptp_tx_hang(struct igc_adapter *adapter) * If we were asked to do hardware stamping and such a time stamp is * available, then it must have been for this skb here because we only * allow only one such packet into the queue. + * + * Context: Expects adapter->ptp_tx_lock to be held by caller. */ static void igc_ptp_tx_hwtstamp(struct igc_adapter *adapter) { @@ -676,13 +678,7 @@ static void igc_ptp_tx_hwtstamp(struct igc_adapter *adapter) shhwtstamps.hwtstamp = ktime_add_ns(shhwtstamps.hwtstamp, adjust); - /* Clear the lock early before calling skb_tstamp_tx so that - * applications are not woken up before the lock bit is clear. We use - * a copy of the skb pointer to ensure other threads can't change it - * while we're notifying the stack. - */ adapter->ptp_tx_skb = NULL; - clear_bit_unlock(__IGC_PTP_TX_IN_PROGRESS, &adapter->state); /* Notify the stack and free the skb after we've unlocked */ skb_tstamp_tx(skb, &shhwtstamps); @@ -693,24 +689,33 @@ static void igc_ptp_tx_hwtstamp(struct igc_adapter *adapter) * igc_ptp_tx_work * @work: pointer to work struct * - * This work function polls the TSYNCTXCTL valid bit to determine when a - * timestamp has been taken for the current stored skb. + * This work function checks the TSYNCTXCTL valid bit to determine when + * a timestamp has been taken for the current stored skb. */ static void igc_ptp_tx_work(struct work_struct *work) { struct igc_adapter *adapter = container_of(work, struct igc_adapter, ptp_tx_work); struct igc_hw *hw = &adapter->hw; + unsigned long flags; u32 tsynctxctl; - if (!test_bit(__IGC_PTP_TX_IN_PROGRESS, &adapter->state)) - return; + spin_lock_irqsave(&adapter->ptp_tx_lock, flags); + + if (!adapter->ptp_tx_skb) + goto unlock; tsynctxctl = rd32(IGC_TSYNCTXCTL); - if (WARN_ON_ONCE(!(tsynctxctl & IGC_TSYNCTXCTL_TXTT_0))) - return; + tsynctxctl &= IGC_TSYNCTXCTL_TXTT_0; + if (!tsynctxctl) { + WARN_ONCE(1, "Received a TSTAMP interrupt but no TSTAMP is ready.\n"); + goto unlock; + } igc_ptp_tx_hwtstamp(adapter); + +unlock: + spin_unlock_irqrestore(&adapter->ptp_tx_lock, flags); } /** @@ -959,6 +964,7 @@ void igc_ptp_init(struct igc_adapter *adapter) return; } + spin_lock_init(&adapter->ptp_tx_lock); spin_lock_init(&adapter->tmreg_lock); INIT_WORK(&adapter->ptp_tx_work, igc_ptp_tx_work); @@ -1023,7 +1029,6 @@ void igc_ptp_suspend(struct igc_adapter *adapter) cancel_work_sync(&adapter->ptp_tx_work); dev_kfree_skb_any(adapter->ptp_tx_skb); adapter->ptp_tx_skb = NULL; - clear_bit_unlock(__IGC_PTP_TX_IN_PROGRESS, &adapter->state); if (pci_device_is_present(adapter->pdev)) { igc_ptp_time_save(adapter); -- 2.40.1 _______________________________________________ Intel-wired-lan mailing list Intel-wired-lan@osuosl.org https://lists.osuosl.org/mailman/listinfo/intel-wired-lan