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Tue, 13 Oct 2026 18:30:17 +0000 (GMT) Received: from localhost.localdomain (unknown [9.67.58.174]) by smtpav03.wdc07v.mail.ibm.com (Postfix) with ESMTP; Tue, 13 Oct 2026 18:30:17 +0000 (GMT) From: Mingming Cao To: netdev@vger.kernel.org Cc: Mingming Cao , maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, ritesh.list@gmail.com, sshegde@linux.ibm.com, nnac123@linux.ibm.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, horms@kernel.org, davemarq@linux.ibm.com, bjking1@linux.ibm.com, stephen@networkplumber.org Subject: [PATCH net-next v5 8/9] ibmveth: wait for the RX poll to return before freeing the RX queue Date: Tue, 13 Oct 2026 11:29:25 -0700 Message-Id: <20261013182926.30417-9-mmc@linux.ibm.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20261013182926.30417-1-mmc@linux.ibm.com> References: <20261013182926.30417-1-mmc@linux.ibm.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDEzMDA3MiBTYWx0ZWRfX1YUaWdYV/t2S afgAxrsm93RLl5BGgu1qtQGkhfm7I/hi3ZS15UsuhTz4E1SEZbYHkhHDQMiG8zQ6AaTPkCW9uiH 82t/SOx2H5eY+TBCbbDlTQgKKp2uVGE= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDEzMDA3MiBTYWx0ZWRfX3tvuoo7Ead4g UVfrp8P+HbEG06DfP2PhChz0dkhS8+nPwnOz50Tsyw/IgstdEPT0g43i+R22mKyEVDhslmJ7YI+ 2JVR7B2Xo20DqGH2974kFYIozCGaCknavxBYGjKSSjB4iKhQO5fHK9nVJULaaqzv2ymXv5nJoxl 1Oe+UyJH55kwiu8tOfr38PGM/+4MvAvlnR1KMQnT5yVEqr3DjGKhmpfV0senIluk5zdb1+T80tH Jkux4ilTruq66+JzTV9dBKnznz08YBwjARUeU1MPkUN5PJYqpg8JvoFxhIYSLOYne8+HudCykU7 G8LtUYixM0pXlHVM+yr2XnTQ4re3ql7AKKPPAzitppIjeFPYSRMyqCV0NhP1l3MCCQdHgfQXj7p YffayL+qSGinjYU87WcdKpoeeZVogfg0RuRnZEvxsvRzEqs+rHfjc+FsBf1+ntLTPIRR156EMcg 9bAURZXxUYOo9X3pBeg== X-Proofpoint-GUID: 0_-J6Vbzkpk1mJ0YCIusBrwqa994kJR6 X-Authority-Analysis: v=2.4 cv=RoFQvymK c=1 sm=1 tr=0 ts=6ace78c0 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=1jQH5Hc4uxvP87yPb2kA:9 X-Proofpoint-ORIG-GUID: w1OCBQgujhshcflORlzpY_9MMPZbOWub X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-13_01,2026-10-09_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 phishscore=0 adultscore=0 bulkscore=0 impostorscore=0 suspectscore=0 malwarescore=0 clxscore=1015 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610130072 napi_disable() returns once ibmveth_poll() has called napi_complete_done(), but the poll is not finished: it then re-enables the interrupt and calls ibmveth_rxq_pending_buffer(), which reads the RX queue. ibmveth_close() can free that queue in the meantime, and the late enable can leave the interrupt unmasked after close() masked it. The request_irq() failure path in ibmveth_open() frees the same memory after napi_disable() too. Call synchronize_net() after napi_disable() on both paths. Every caller of ibmveth_poll() runs it with bottom halves or interrupts disabled, so this waits for the poll to return. Found in review of the ibmveth multi-queue RX series and confirmed by code inspection; also raised by the Sashiko review of the first version of this series. The race was not reproduced. Tested on a POWER10 LPAR under an incoming ping flood with 30 rapid link down/up cycles and 30 rapid MTU cycles (1500 <-> 9000); ran cleanly with no warnings or faults. No kernel selftests cover ibmveth. Fixes: bea3348eef27 ("[NET]: Make NAPI polling independent of struct net_device objects.") Signed-off-by: Mingming Cao --- Changes in v2: - new patch; raised by the Sashiko review of v1 patch 1 as a pre-existing bug drivers/net/ethernet/ibm/ibmveth.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/net/ethernet/ibm/ibmveth.c b/drivers/net/ethernet/ibm/ibmveth.c index f2570d637301..85e176d0ed32 100644 --- a/drivers/net/ethernet/ibm/ibmveth.c +++ b/drivers/net/ethernet/ibm/ibmveth.c @@ -768,6 +768,7 @@ static int ibmveth_open(struct net_device *netdev) netdev); if (rc != 0) { napi_disable(&adapter->napi); + synchronize_net(); netdev_err(netdev, "unable to request irq 0x%x, rc %d\n", netdev->irq, rc); goto out_free_buffer_pools; @@ -834,6 +835,11 @@ static int ibmveth_close(struct net_device *netdev) netdev_dbg(netdev, "close starting\n"); napi_disable(&adapter->napi); + /* napi_disable() returns once ibmveth_poll() has called + * napi_complete_done(), but the poll still re-enables the + * interrupt and reads the RX queue after that. + */ + synchronize_net(); netif_tx_disable(netdev); -- 2.50.1 (Apple Git-155)