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GET /api/patches/2215384/?format=api
{ "id": 2215384, "url": "http://patchwork.ozlabs.org/api/patches/2215384/?format=api", "web_url": "http://patchwork.ozlabs.org/project/intel-wired-lan/patch/20260324130922.562714-1-aleksandr.loktionov@intel.com/", "project": { "id": 46, "url": "http://patchwork.ozlabs.org/api/projects/46/?format=api", "name": "Intel Wired Ethernet development", "link_name": "intel-wired-lan", "list_id": "intel-wired-lan.osuosl.org", "list_email": "intel-wired-lan@osuosl.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260324130922.562714-1-aleksandr.loktionov@intel.com>", "list_archive_url": null, "date": "2026-03-24T13:09:22", "name": "[iwl-net,v1] i40e: fix napi_enable/disable skipping ringless q_vectors", "commit_ref": null, "pull_url": null, "state": "under-review", "archived": false, "hash": "6a070f9a718f3b32218a7d3feb9be64c36d64ad9", "submitter": { "id": 75597, "url": "http://patchwork.ozlabs.org/api/people/75597/?format=api", "name": "Loktionov, Aleksandr", "email": "aleksandr.loktionov@intel.com" }, "delegate": { "id": 109701, "url": "http://patchwork.ozlabs.org/api/users/109701/?format=api", "username": "anguy11", "first_name": "Anthony", "last_name": "Nguyen", "email": "anthony.l.nguyen@intel.com" }, "mbox": "http://patchwork.ozlabs.org/project/intel-wired-lan/patch/20260324130922.562714-1-aleksandr.loktionov@intel.com/mbox/", "series": [ { "id": 497284, "url": "http://patchwork.ozlabs.org/api/series/497284/?format=api", "web_url": "http://patchwork.ozlabs.org/project/intel-wired-lan/list/?series=497284", "date": "2026-03-24T13:09:22", "name": "[iwl-net,v1] i40e: fix napi_enable/disable skipping ringless q_vectors", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/497284/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2215384/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2215384/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<intel-wired-lan-bounces@osuosl.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "intel-wired-lan@lists.osuosl.org" ], "Delivered-To": [ "patchwork-incoming@legolas.ozlabs.org", "intel-wired-lan@lists.osuosl.org" ], "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=osuosl.org header.i=@osuosl.org header.a=rsa-sha256\n header.s=default header.b=fEZPoTK1;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=osuosl.org\n (client-ip=2605:bc80:3010::138; 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envelope-from=intel-wired-lan-bounces@osuosl.org;\n receiver=<UNKNOWN> ", "DKIM-Filter": [ "OpenDKIM Filter v2.11.0 smtp1.osuosl.org 6167C82572", "OpenDKIM Filter v2.11.0 smtp1.osuosl.org B0B6E822A9" ], "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed; d=osuosl.org;\n\ts=default; t=1774357768;\n\tbh=M7ouG0DBC3XldW/b7H0aRP+nZ9yTbmC+VQ/AifZR8ek=;\n\th=From:To:Cc:Date:Subject:List-Id:List-Unsubscribe:List-Archive:\n\t List-Post:List-Help:List-Subscribe:From;\n\tb=fEZPoTK1DvASC4W2Mid70ylL0nghZyiCUQb9b1XEm2ZLRxowvn16EPxY4e7rkxcnz\n\t t7MchTcE+vC0tcWcL91bTnRpoScKgQ+S3AiGo+4BBX9qitkviLYo43+hksjL+jCyxm\n\t nskTycIHT3cJA2kN+MdACrhxz+ILZaMDjtf415SYCQiull1hirUhv9xM3bdipBQJef\n\t M3e+W22TX1PHoRzMNyPNfSXSM2HK6d6C4ul0GmvY1PpoOB2haR76sRwWGg4gBRC8Qb\n\t 972+YI9jrzVtdgdvh0m3FtcdIC1A98T3MrNse/hjKFFbbXwijz84aG1jdiI92vHHca\n\t iAzzAzBzAuYUQ==", "Received-SPF": "Pass (mailfrom) identity=mailfrom; client-ip=192.198.163.13;\n helo=mgamail.intel.com; envelope-from=aleksandr.loktionov@intel.com;\n receiver=<UNKNOWN>", "DMARC-Filter": "OpenDMARC Filter v1.4.2 smtp1.osuosl.org B0B6E822A9", "X-CSE-ConnectionGUID": [ "x9/UFbZpRLiuhX1bgyIAVg==", "1if/zWsiRuy9X9x3yuid1w==" ], "X-CSE-MsgGUID": [ "NI/9vYipR5Oy3SnkDKJ9kA==", "4l+BDvUWQdepVfqWHfssWA==" ], "X-IronPort-AV": [ "E=McAfee;i=\"6800,10657,11739\"; a=\"77975892\"", "E=Sophos;i=\"6.23,138,1770624000\"; d=\"scan'208\";a=\"77975892\"", "E=Sophos;i=\"6.23,138,1770624000\"; d=\"scan'208\";a=\"228400158\"" ], "X-ExtLoop1": "1", "From": "Aleksandr Loktionov <aleksandr.loktionov@intel.com>", "To": "intel-wired-lan@lists.osuosl.org, anthony.l.nguyen@intel.com,\n aleksandr.loktionov@intel.com", "Cc": "netdev@vger.kernel.org,\n\tJakub Kicinski <kuba@kernel.org>", "Date": "Tue, 24 Mar 2026 14:09:22 +0100", "Message-ID": "<20260324130922.562714-1-aleksandr.loktionov@intel.com>", "X-Mailer": "git-send-email 2.52.0", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "X-Mailman-Original-DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple;\n d=intel.com; i=@intel.com; q=dns/txt; s=Intel;\n t=1774357766; x=1805893766;\n h=from:to:cc:subject:date:message-id:mime-version:\n content-transfer-encoding;\n bh=7IExQLdoaklosTrWWL0AAMEuAjaaUus+8pe4mqx3XOU=;\n b=S7JyPlaubYLFsiQ+4rK0HcZ5E1SVivFd5rB7FYhJl1P9PkD0bYd5mvpj\n HdmnF1dwENwSufCXyv2QpTtEZgtwCKd1MNfccDZr1l96srFWCpBuzSv7a\n ygO2pOiXqyNWOwLLTngt2Z73hOst4UFMDoUa2ZMpgciq0/C2KH7fjl8YA\n B22FWiZ9ZYTNkoslSqLohAUXnHubErTTY7gUKmchlWprVHQ0Ih6fGyOre\n o43aPuEMFoGlMJWRaUmSbBEKggP7OAVHnw/3HHQrKH+OyYEmISYOwOfph\n 1Y9fKXAynjP/J8FXob0uFBsjOhrRwK3N899K/RjaIOuZlGWctmKiRn/ZJ\n Q==;", "X-Mailman-Original-Authentication-Results": [ "smtp1.osuosl.org;\n dmarc=pass (p=none dis=none)\n header.from=intel.com", "smtp1.osuosl.org;\n dkim=pass (2048-bit key,\n unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256\n header.s=Intel header.b=S7JyPlau" ], "Subject": "[Intel-wired-lan] [PATCH iwl-net v1] i40e: fix napi_enable/disable\n skipping ringless q_vectors", "X-BeenThere": "intel-wired-lan@osuosl.org", "X-Mailman-Version": "2.1.30", "Precedence": "list", "List-Id": "Intel Wired Ethernet Linux Kernel Driver Development\n <intel-wired-lan.osuosl.org>", "List-Unsubscribe": "<https://lists.osuosl.org/mailman/options/intel-wired-lan>,\n <mailto:intel-wired-lan-request@osuosl.org?subject=unsubscribe>", "List-Archive": "<http://lists.osuosl.org/pipermail/intel-wired-lan/>", "List-Post": "<mailto:intel-wired-lan@osuosl.org>", "List-Help": "<mailto:intel-wired-lan-request@osuosl.org?subject=help>", "List-Subscribe": "<https://lists.osuosl.org/mailman/listinfo/intel-wired-lan>,\n <mailto:intel-wired-lan-request@osuosl.org?subject=subscribe>", "Errors-To": "intel-wired-lan-bounces@osuosl.org", "Sender": "\"Intel-wired-lan\" <intel-wired-lan-bounces@osuosl.org>" }, "content": "After ethtool -L reduces the queue count, i40e_napi_disable_all() sets\nNAPI_STATE_SCHED on all q_vectors, then i40e_vsi_map_rings_to_vectors()\nclears ring pointers on the excess ones. i40e_napi_enable_all() skips\nthose with:\n\n\tif (q_vector->rx.ring || q_vector->tx.ring)\n\t\tnapi_enable(&q_vector->napi);\n\nleaving them on dev->napi_list with NAPI_STATE_SCHED permanently set.\n\nWriting to /sys/class/net/<iface>/threaded calls napi_stop_kthread()\non every entry in dev->napi_list. The function loops on msleep(20)\nwaiting for NAPI_STATE_SCHED to clear -- which never happens for the\nstale q_vectors. The task hangs in D state forever; a concurrent write\ndeadlocks on dev->lock held by the first.\n\nCommit 13a8cd191a2b added the guard to prevent a divide-by-zero in\ni40e_napi_poll() when epoll busy-poll iterated all device NAPIs (4.x\nera). Since 7adc3d57fe2b (\"net: Introduce preferred busy-polling\",\nv5.11) napi_busy_loop() polls by napi_id keyed to the socket, so\nringless q_vectors are never selected. i40e_msix_clean_rings() also\nindependently avoids scheduling NAPI for them. The guard is safe to\nremove.\n\nAdd an early return in i40e_napi_poll() for num_ringpairs == 0 so the\nfunction is self-defending against a NULL tx.ring dereference at the\nWB_ON_ITR check, should the NAPI ever fire through an unexpected path.\n\nReported-by: Jakub Kicinski <kuba@kernel.org>\nCloses: https://lore.kernel.org/intel-wired-lan/20260316133100.6054a11f@kernel.org/\nFixes: 13a8cd191a2b (\"i40e: Do not enable NAPI on q_vectors that have no rings\")\nCc: stable@vger.kernel.org\nSigned-off-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>\n---\nTest configuration:\n Kernel : Linux 6.19.0-rc8+\n NIC : Intel Ethernet Controller XXV710 for 25GbE SFP28 [8086:158b]\n Driver : i40e (in-tree)\n Firmware : 9.40 0x8000ed12 1.3429.0\n CPU : 2 x Intel Xeon Gold 6238M (88 logical CPUs, x86_64)\n RAM : 64 GiB\n\nReproduction steps (FAIL before fix):\n # 1. Reduce queues so excess q_vectors lose their ring pointers\n ethtool -L <iface> combined 1\n\n # 2. Enable threaded NAPI (completes fast in 6.19, no hang on enable path)\n echo 1 > /sys/class/net/<iface>/threaded\n\n # 3. Two concurrent writes to disable -- fires the msleep deadlock\n echo 0 > /sys/class/net/<iface>/threaded &\n echo 0 > /sys/class/net/<iface>/threaded &\n\n Both background tasks enter uninterruptible sleep (D state) immediately\n and never return.\n\n Observed kernel stack (W1, holds dev->lock):\n msleep+0x2d/0x50\n napi_set_threaded+0x10b/0x110\n netif_set_threaded+0xe1/0x140\n threaded_store+0xd2/0x100\n kernfs_fop_write_iter+0x138/0x1d0\n\n Kernel hung_task message (~120 s after trigger):\n INFO: task bash blocked for more than 122 seconds.\n INFO: task bash is blocked on a mutex likely owned by task bash.\n\nValidation (PASS with fix):\n Both background tasks exit within 1 second.\n D-state process count: 0.\n Busy-poll (net.core.busy_poll=50) + 50000-packet UDP flood with\n 1 active queue: no NULL dereference, no crash.\n\n drivers/net/ethernet/intel/i40e/i40e_main.c | 28 ++++++++++++---------\n drivers/net/ethernet/intel/i40e/i40e_txrx.c | 10 ++++++++\n 2 files changed, 26 insertions(+), 12 deletions(-)", "diff": "diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c\nindex 926d001..5042f8c 100644\n--- a/drivers/net/ethernet/intel/i40e/i40e_main.c\n+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c\n@@ -5182,6 +5182,14 @@ static void i40e_clear_interrupt_scheme(struct i40e_pf *pf)\n /**\n * i40e_napi_enable_all - Enable NAPI for all q_vectors in the VSI\n * @vsi: the VSI being configured\n+ *\n+ * Enable NAPI on every q_vector that is registered with the netdev,\n+ * regardless of whether it currently has rings assigned. After a queue-\n+ * count reduction (e.g. ethtool -L combined 1) the excess q_vectors lose\n+ * their ring pointers inside i40e_vsi_map_rings_to_vectors but remain on\n+ * dev->napi_list. Leaving them in the napi_disable()-ed state\n+ * (NAPI_STATE_SCHED set) causes napi_set_threaded() to spin forever on\n+ * msleep(20) waiting for that bit to clear.\n **/\n static void i40e_napi_enable_all(struct i40e_vsi *vsi)\n {\n@@ -5190,17 +5198,17 @@ static void i40e_napi_enable_all(struct i40e_vsi *vsi)\n \tif (!vsi->netdev)\n \t\treturn;\n \n-\tfor (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++) {\n-\t\tstruct i40e_q_vector *q_vector = vsi->q_vectors[q_idx];\n-\n-\t\tif (q_vector->rx.ring || q_vector->tx.ring)\n-\t\t\tnapi_enable(&q_vector->napi);\n-\t}\n+\tfor (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++)\n+\t\tnapi_enable(&vsi->q_vectors[q_idx]->napi);\n }\n \n /**\n * i40e_napi_disable_all - Disable NAPI for all q_vectors in the VSI\n * @vsi: the VSI being configured\n+ *\n+ * Mirror of i40e_napi_enable_all: operate on every registered q_vector so\n+ * enable/disable calls are always balanced, even when some q_vectors carry\n+ * no rings (as happens after a queue-count reduction).\n **/\n static void i40e_napi_disable_all(struct i40e_vsi *vsi)\n {\n@@ -5209,12 +5217,8 @@ static void i40e_napi_disable_all(struct i40e_vsi *vsi)\n \tif (!vsi->netdev)\n \t\treturn;\n \n-\tfor (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++) {\n-\t\tstruct i40e_q_vector *q_vector = vsi->q_vectors[q_idx];\n-\n-\t\tif (q_vector->rx.ring || q_vector->tx.ring)\n-\t\t\tnapi_disable(&q_vector->napi);\n-\t}\n+\tfor (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++)\n+\t\tnapi_disable(&vsi->q_vectors[q_idx]->napi);\n }\n \n /**\ndiff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c\nindex 894f2d0..3123459 100644\n--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c\n+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c\n@@ -2760,6 +2760,16 @@ int i40e_napi_poll(struct napi_struct *napi, int budget)\n \t\treturn 0;\n \t}\n \n+\t/* A q_vector can have its ring pointers cleared after a queue-count\n+\t * reduction (ethtool -L combined N) while napi_enable() was already\n+\t * called on it. Complete immediately so the poll loop exits cleanly\n+\t * and we never dereference the NULL ring pointer below.\n+\t */\n+\tif (unlikely(!q_vector->num_ringpairs)) {\n+\t\tnapi_complete_done(napi, 0);\n+\t\treturn 0;\n+\t}\n+\n \t/* Since the actual Tx work is minimal, we can give the Tx a larger\n \t * budget and be more aggressive about cleaning up the Tx descriptors.\n \t */\n", "prefixes": [ "iwl-net", "v1" ] }