6.1-stable review patch. If anyone has any objections, please let me know.
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From: Vinicius Costa Gomes vinicius.gomes@intel.com
commit 9c50e2b150c8ee0eee5f8154e2ad168cdd748877 upstream.
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 andre.guedes@intel.com Signed-off-by: Vinicius Costa Gomes vinicius.gomes@intel.com Reviewed-by: Kurt Kanzenbach kurt@linutronix.de Tested-by: Naama Meir naamax.meir@linux.intel.com Signed-off-by: Tony Nguyen anthony.l.nguyen@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 | 57 ++++++++++++++++-------------- 3 files changed, 41 insertions(+), 30 deletions(-)
--- a/drivers/net/ethernet/intel/igc/igc.h +++ b/drivers/net/ethernet/intel/igc/igc.h @@ -230,6 +230,10 @@ 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; @@ -431,7 +435,6 @@ enum igc_state_t { __IGC_TESTING, __IGC_RESETTING, __IGC_DOWN, - __IGC_PTP_TX_IN_PROGRESS, };
enum igc_tx_flags { --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -1606,9 +1606,10 @@ done: * 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;
@@ -1617,6 +1618,8 @@ done: } else { adapter->tx_hwtstamp_skipped++; } + + spin_unlock_irqrestore(&adapter->ptp_tx_lock, flags); }
if (skb_vlan_tag_present(skb)) { --- a/drivers/net/ethernet/intel/igc/igc_ptp.c +++ b/drivers/net/ethernet/intel/igc/igc_ptp.c @@ -622,6 +622,7 @@ static int igc_ptp_set_timestamp_mode(st 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; @@ -629,7 +630,6 @@ static void igc_ptp_tx_timeout(struct ig 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"); @@ -637,20 +637,20 @@ static void igc_ptp_tx_timeout(struct ig
void igc_ptp_tx_hang(struct igc_adapter *adapter) { - bool timeout = time_is_before_jiffies(adapter->ptp_tx_start + - IGC_PTP_TX_TIMEOUT); + unsigned long flags;
- if (!test_bit(__IGC_PTP_TX_IN_PROGRESS, &adapter->state)) - return; + spin_lock_irqsave(&adapter->ptp_tx_lock, flags);
- /* 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); - } + 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); }
/** @@ -660,6 +660,8 @@ void igc_ptp_tx_hang(struct igc_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) { @@ -695,13 +697,7 @@ static void igc_ptp_tx_hwtstamp(struct i 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); @@ -712,24 +708,33 @@ static void igc_ptp_tx_hwtstamp(struct i * 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); }
/** @@ -978,6 +983,7 @@ void igc_ptp_init(struct igc_adapter *ad return; }
+ spin_lock_init(&adapter->ptp_tx_lock); spin_lock_init(&adapter->tmreg_lock); INIT_WORK(&adapter->ptp_tx_work, igc_ptp_tx_work);
@@ -1042,7 +1048,6 @@ void igc_ptp_suspend(struct igc_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);