From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 00DCE5172EF; Wed, 30 Sep 2026 16:56:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790787384; cv=none; b=i8mbf1CX326KvQMR1R8kKCYpSgxjVfAbW2k8326Pta/Yg/UYFxsegwpl/6Y7fdv6lm0arkAZ+JYEVqikymeT7Tnz+l7MknofybfA1vB1YcqJ3DOD3YQ/CYFld2DnGlwS9jPEefq91xozsDSkAopSSygwc7cVwxCXeJnacAtehD8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790787384; c=relaxed/simple; bh=4Rn9tnsL2l4fYAUC6ukMhXKXlM6SClIQTzUYb5ltpw8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=L2nWx3uQFGtqSZLGs1EkEEORkuNZ1TswdfHi4r5GmqP9Rmyg8hmjiWJpOPYlZ85pNPYP3m1yNVAKPZ84811iCg9066qhpv+1O4c96/ZKjVWuPpClmSGn38K1o6vpFU5jo1u0yMA8D2w7HyX3SVz0dBo03iXcoiSxhWZuTQ/gxM8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=iGo+QtSe; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="iGo+QtSe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0DF5B1F000FF; Wed, 30 Sep 2026 16:56:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790787382; bh=4Ixc53lRSzraMIPnJNEuPqEBymd7uiExdZEsikx5UYo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iGo+QtSemhp4Z9yQiVDfwbZATkqDxIXEKsT5L6d5W2y+TTyL0i2MyS3ctppH0H9DV OE8ZWushaBTpkkpab0K53y8xlhe4w6/4gDESkBFcKGOA93Jf66Zrt/4Mqspc/qv7ne lPN9Gk1ZweHRCI2kqb+tbXCniyRejvcED+ujNMu0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sashiko , Jiawen Wu , Jakub Kicinski , Sasha Levin Subject: [PATCH 7.2 212/457] net: libwx: fix races in Tx timestamp handling Date: Wed, 30 Sep 2026 17:25:17 +0200 Message-ID: <20260930152350.626678429@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152346.024115587@linuxfoundation.org> References: <20260930152346.024115587@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiawen Wu [ Upstream commit 3173cba1170131816972ed2b6185cb970ba8b747 ] wx->ptp_tx_skb is shared between the Tx path, the PTP auxiliary worker and the timestamp cleanup paths. The WX_STATE_PTP_TX_IN_PROGRESS bit prevents multiple Tx paths from submitting timestamp requests, but does not serialize the worker against cleanup. As a result, wx_ptp_clear_tx_timestamp() can free an skb after wx_ptp_tx_hwtstamp_work() has obtained its pointer. The worker may then pass the freed skb to skb_tstamp_tx() and release the same reference again. The cleanup path may also clear the in-progress bit while the worker is still processing the old skb. This allows the Tx path to publish a new skb which the worker can subsequently overwrite with NULL, leaking its reference. Add a dedicated spinlock to protect publication and consumption of the Tx timestamp skb. Detach the skb and clear the in-progress bit while holding the lock, then deliver the timestamp and release the skb after dropping it. Use the same locked cleanup in the quiesce path, but keep the detach there free of register accesses: quiesce runs during PCIe error recovery, where MMIO is not reliable, and it deliberately did not touch the device before. The lock is taken with interrupts disabled, because netpoll can call ndo_start_xmit() with hard interrupts already off. When handling a Tx DMA mapping failure, keep the transmit path reference until after comparing the skb under the lock. This prevents skb address reuse from making the error path mistake a newer timestamp request for the failed one. Fixes: 06e75161b9d4 ("net: wangxun: Add support for PTP clock") Reported-by: Sashiko Link: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/6C7EC12D69217315%2B20260818074721.45536-1-jiawenwu%40trustnetic.com Signed-off-by: Jiawen Wu Link: https://patch.msgid.link/77431AF9A0E369F3+20260921071549.1141804-1-jiawenwu@trustnetic.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/ethernet/wangxun/libwx/wx_hw.c | 1 + drivers/net/ethernet/wangxun/libwx/wx_lib.c | 47 ++++-- drivers/net/ethernet/wangxun/libwx/wx_ptp.c | 142 +++++++++++++------ drivers/net/ethernet/wangxun/libwx/wx_type.h | 2 + 4 files changed, 132 insertions(+), 60 deletions(-) diff --git a/drivers/net/ethernet/wangxun/libwx/wx_hw.c b/drivers/net/ethernet/wangxun/libwx/wx_hw.c index 260e14d5d5412..9119c931b3a3f 100644 --- a/drivers/net/ethernet/wangxun/libwx/wx_hw.c +++ b/drivers/net/ethernet/wangxun/libwx/wx_hw.c @@ -2517,6 +2517,7 @@ int wx_sw_init(struct wx *wx) } spin_lock_init(&wx->hw_stats_lock); + spin_lock_init(&wx->ptp_tx_lock); mutex_init(&wx->reset_lock); bitmap_zero(wx->state, WX_STATE_NBITS); bitmap_zero(wx->flags, WX_PF_FLAGS_NBITS); diff --git a/drivers/net/ethernet/wangxun/libwx/wx_lib.c b/drivers/net/ethernet/wangxun/libwx/wx_lib.c index 7e2ae41a321e1..287172348b07e 100644 --- a/drivers/net/ethernet/wangxun/libwx/wx_lib.c +++ b/drivers/net/ethernet/wangxun/libwx/wx_lib.c @@ -1163,9 +1163,11 @@ static int wx_tx_map(struct wx_ring *tx_ring, i--; } - dev_kfree_skb_any(first->skb); - first->skb = NULL; - + /* first->skb is released by the caller, which keeps a reference on it + * until the PTP cleanup has compared it against wx->ptp_tx_skb. That + * prevents the address from being reused by a newer request while the + * comparison is pending. + */ tx_ring->next_to_use = i; return -ENOMEM; @@ -1612,9 +1614,11 @@ static netdev_tx_t wx_xmit_frame_ring(struct sk_buff *skb, if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) && wx->ptp_clock) { + unsigned long flags; + + spin_lock_irqsave(&wx->ptp_tx_lock, flags); if (wx->tstamp_config.tx_type == HWTSTAMP_TX_ON && - !test_and_set_bit_lock(WX_STATE_PTP_TX_IN_PROGRESS, - wx->state)) { + !test_and_set_bit(WX_STATE_PTP_TX_IN_PROGRESS, wx->state)) { skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS; tx_flags |= WX_TX_FLAGS_TSTAMP; wx->ptp_tx_skb = skb_get(skb); @@ -1622,6 +1626,7 @@ static netdev_tx_t wx_xmit_frame_ring(struct sk_buff *skb, } else { wx->tx_hwtstamp_skipped++; } + spin_unlock_irqrestore(&wx->ptp_tx_lock, flags); } /* record initial flags and protocol */ @@ -1640,19 +1645,35 @@ static netdev_tx_t wx_xmit_frame_ring(struct sk_buff *skb, wx->atr(tx_ring, first, ptype); if (wx_tx_map(tx_ring, first, hdr_len)) - goto cleanup_tx_tstamp; + goto out_drop; return NETDEV_TX_OK; out_drop: - dev_kfree_skb_any(first->skb); - first->skb = NULL; -cleanup_tx_tstamp: + /* The frame never reached the hardware, so no timestamp will ever be + * reported for it and the request has to be cancelled. The slot is + * shared, though: wx_ptp_clear_tx_timestamp() or wx_ptp_tx_hang() may + * have dropped our request already, and a transmit on another queue + * can have claimed the slot since. Only cancel it while it is still + * ours, otherwise we would free somebody else's skb and release their + * in-progress bit. + */ if (unlikely(tx_flags & WX_TX_FLAGS_TSTAMP)) { - dev_kfree_skb_any(wx->ptp_tx_skb); - wx->ptp_tx_skb = NULL; - wx->tx_hwtstamp_errors++; - clear_bit_unlock(WX_STATE_PTP_TX_IN_PROGRESS, wx->state); + struct sk_buff *ptp_tx_skb = NULL; + unsigned long flags; + + spin_lock_irqsave(&wx->ptp_tx_lock, flags); + if (wx->ptp_tx_skb == skb) { + ptp_tx_skb = wx->ptp_tx_skb; + wx->ptp_tx_skb = NULL; + clear_bit(WX_STATE_PTP_TX_IN_PROGRESS, wx->state); + wx->tx_hwtstamp_errors++; + } + spin_unlock_irqrestore(&wx->ptp_tx_lock, flags); + + dev_kfree_skb_any(ptp_tx_skb); } + dev_kfree_skb_any(first->skb); + first->skb = NULL; return NETDEV_TX_OK; } diff --git a/drivers/net/ethernet/wangxun/libwx/wx_ptp.c b/drivers/net/ethernet/wangxun/libwx/wx_ptp.c index 4708e7f3958f7..65b8937f6e94c 100644 --- a/drivers/net/ethernet/wangxun/libwx/wx_ptp.c +++ b/drivers/net/ethernet/wangxun/libwx/wx_ptp.c @@ -129,6 +129,34 @@ static int wx_ptp_settime64(struct ptp_clock_info *ptp, return 0; } +/** + * __wx_ptp_detach_tx_skb - detach the skb tracking the Tx timestamp request + * @wx: the private board structure + * + * Detach the skb of the outstanding request and release the in-progress bit, + * so that a new request can be submitted. + * + * This performs no register access. Callers that need a timestamp the hardware + * may have left latched must unlatch it themselves, while the device is known + * to be alive. wx_ptp_quiesce() runs during PCIe error recovery, where MMIO is + * not reliable, and therefore deliberately skips the unlatch. + * + * Context: Expects wx->ptp_tx_lock to be held by the caller. + * Return: the detached skb, or NULL if no request was outstanding. The caller + * owns the returned reference and must release it once the lock is dropped. + */ +static struct sk_buff *__wx_ptp_detach_tx_skb(struct wx *wx) +{ + struct sk_buff *skb = wx->ptp_tx_skb; + + lockdep_assert_held(&wx->ptp_tx_lock); + + wx->ptp_tx_skb = NULL; + clear_bit(WX_STATE_PTP_TX_IN_PROGRESS, wx->state); + + return skb; +} + /** * wx_ptp_clear_tx_timestamp - utility function to clear Tx timestamp state * @wx: the private board structure @@ -139,12 +167,16 @@ static int wx_ptp_settime64(struct ptp_clock_info *ptp, */ static void wx_ptp_clear_tx_timestamp(struct wx *wx) { + struct sk_buff *skb; + unsigned long flags; + + spin_lock_irqsave(&wx->ptp_tx_lock, flags); + /* Unlatch a timestamp the hardware may have left pending. */ rd32ptp(wx, WX_TSC_1588_STMPH); - if (wx->ptp_tx_skb) { - dev_kfree_skb_any(wx->ptp_tx_skb); - wx->ptp_tx_skb = NULL; - } - clear_bit_unlock(WX_STATE_PTP_TX_IN_PROGRESS, wx->state); + skb = __wx_ptp_detach_tx_skb(wx); + spin_unlock_irqrestore(&wx->ptp_tx_lock, flags); + + dev_kfree_skb_any(skb); } /** @@ -175,49 +207,54 @@ static void wx_ptp_convert_to_hwtstamp(struct wx *wx, } /** - * wx_ptp_tx_hwtstamp - utility function which checks for TX time stamp + * wx_ptp_tx_hwtstamp_work - check for a pending Tx time stamp * @wx: the private board struct * - * if the timestamp is valid, we convert it into the timecounter ns - * value, then store that result into the shhwtstamps structure which - * is passed up the network stack + * If a Tx timestamp request is outstanding and the hardware has latched a + * valid value, we convert it into the timecounter ns value, then store that + * result into the shhwtstamps structure which is passed up the network stack. + * + * Return: 0 when there is nothing left to poll for, -1 when the timestamp is + * not available yet and the caller should poll again. */ -static void wx_ptp_tx_hwtstamp(struct wx *wx) +static int wx_ptp_tx_hwtstamp_work(struct wx *wx) { struct skb_shared_hwtstamps shhwtstamps; - struct sk_buff *skb = wx->ptp_tx_skb; + unsigned long flags; + struct sk_buff *skb; + u32 tsynctxctl; u64 regval = 0; - regval |= (u64)rd32ptp(wx, WX_TSC_1588_STMPL); - regval |= (u64)rd32ptp(wx, WX_TSC_1588_STMPH) << 32; - - wx_ptp_convert_to_hwtstamp(wx, &shhwtstamps, regval); - - wx->ptp_tx_skb = NULL; - clear_bit_unlock(WX_STATE_PTP_TX_IN_PROGRESS, wx->state); - skb_tstamp_tx(skb, &shhwtstamps); - dev_kfree_skb_any(skb); - wx->tx_hwtstamp_pkts++; -} - -static int wx_ptp_tx_hwtstamp_work(struct wx *wx) -{ - u32 tsynctxctl; + spin_lock_irqsave(&wx->ptp_tx_lock, flags); /* we have to have a valid skb to poll for a timestamp */ if (!wx->ptp_tx_skb) { - wx_ptp_clear_tx_timestamp(wx); + rd32ptp(wx, WX_TSC_1588_STMPH); + __wx_ptp_detach_tx_skb(wx); + spin_unlock_irqrestore(&wx->ptp_tx_lock, flags); return 0; } /* stop polling once we have a valid timestamp */ tsynctxctl = rd32ptp(wx, WX_TSC_1588_CTL); - if (tsynctxctl & WX_TSC_1588_CTL_VALID) { - wx_ptp_tx_hwtstamp(wx); - return 0; + if (!(tsynctxctl & WX_TSC_1588_CTL_VALID)) { + spin_unlock_irqrestore(&wx->ptp_tx_lock, flags); + return -1; } - return -1; + regval |= (u64)rd32ptp(wx, WX_TSC_1588_STMPL); + regval |= (u64)rd32ptp(wx, WX_TSC_1588_STMPH) << 32; + skb = wx->ptp_tx_skb; + wx->ptp_tx_skb = NULL; + clear_bit(WX_STATE_PTP_TX_IN_PROGRESS, wx->state); + spin_unlock_irqrestore(&wx->ptp_tx_lock, flags); + + wx_ptp_convert_to_hwtstamp(wx, &shhwtstamps, regval); + skb_tstamp_tx(skb, &shhwtstamps); + dev_kfree_skb_any(skb); + wx->tx_hwtstamp_pkts++; + + return 0; } /** @@ -296,24 +333,29 @@ static void wx_ptp_rx_hang(struct wx *wx) */ static void wx_ptp_tx_hang(struct wx *wx) { - bool timeout = time_is_before_jiffies(wx->ptp_tx_start + - WX_PTP_TX_TIMEOUT); - - if (!wx->ptp_tx_skb) - return; + struct sk_buff *skb = NULL; + unsigned long flags; - if (!test_bit(WX_STATE_PTP_TX_IN_PROGRESS, wx->state)) - return; + spin_lock_irqsave(&wx->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) { - wx_ptp_clear_tx_timestamp(wx); - wx->tx_hwtstamp_timeouts++; - dev_warn(&wx->pdev->dev, "clearing Tx timestamp hang\n"); + if (wx->ptp_tx_skb && + test_bit(WX_STATE_PTP_TX_IN_PROGRESS, wx->state) && + time_is_before_jiffies(wx->ptp_tx_start + WX_PTP_TX_TIMEOUT)) { + rd32ptp(wx, WX_TSC_1588_STMPH); + skb = __wx_ptp_detach_tx_skb(wx); } + spin_unlock_irqrestore(&wx->ptp_tx_lock, flags); + + if (!skb) + return; + + dev_kfree_skb_any(skb); + wx->tx_hwtstamp_timeouts++; + dev_warn(&wx->pdev->dev, "clearing Tx timestamp hang\n"); } static long wx_ptp_do_aux_work(struct ptp_clock_info *ptp) @@ -841,6 +883,9 @@ EXPORT_SYMBOL(wx_ptp_stop); void wx_ptp_quiesce(struct wx *wx) { + struct sk_buff *skb; + unsigned long flags; + if (!test_and_clear_bit(WX_STATE_PTP_RUNNING, wx->state)) return; @@ -849,11 +894,14 @@ void wx_ptp_quiesce(struct wx *wx) if (wx->ptp_clock) ptp_cancel_worker_sync(wx->ptp_clock); - if (wx->ptp_tx_skb) { - dev_kfree_skb_any(wx->ptp_tx_skb); - wx->ptp_tx_skb = NULL; - } - clear_bit_unlock(WX_STATE_PTP_TX_IN_PROGRESS, wx->state); + /* Drop a pending Tx timestamp request. Do not touch the registers + * here: quiesce runs during PCIe error recovery, where the device may + * already be gone and MMIO is not reliable. + */ + spin_lock_irqsave(&wx->ptp_tx_lock, flags); + skb = __wx_ptp_detach_tx_skb(wx); + spin_unlock_irqrestore(&wx->ptp_tx_lock, flags); + dev_kfree_skb_any(skb); if (wx->ptp_clock) { ptp_clock_unregister(wx->ptp_clock); diff --git a/drivers/net/ethernet/wangxun/libwx/wx_type.h b/drivers/net/ethernet/wangxun/libwx/wx_type.h index 0520288d18ab9..e63a1666d8ed1 100644 --- a/drivers/net/ethernet/wangxun/libwx/wx_type.h +++ b/drivers/net/ethernet/wangxun/libwx/wx_type.h @@ -1413,6 +1413,8 @@ struct wx { unsigned long last_overflow_check; unsigned long last_rx_ptp_check; unsigned long ptp_tx_start; + /* protects ptp_tx_skb, ptp_tx_start and the in-progress state bit */ + spinlock_t ptp_tx_lock; seqlock_t hw_tc_lock; /* seqlock for ptp */ struct cyclecounter hw_cc; struct timecounter hw_tc; -- 2.53.0