From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (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 1859533C1AD; Mon, 9 Mar 2026 20:24:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773087858; cv=none; b=QXsE7OrMc4MAcia84QemVw+YLIUhfJAj86oRat9UIyasP6PLIbhmAPKMpk6xNKijO0gS6RO813I2cqJO9AjKowHsu3e1qNGLzi6fwirUEsAX1ZX+pMsSrOHCDj3j+9uE42zBvw9m+VKurUvlpoTdjLLI/dNOneoCQ9OXWNx1tpM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773087858; c=relaxed/simple; bh=il727WXEbted9aOs3KJ2E5+QhZbWwZnQlz4+CEpInBE=; h=Message-ID:Subject:From:To:Cc:In-Reply-To:References:Content-Type: Date:MIME-Version; b=muyjX7iZDzL7V3BXse9+Y777Jk0fvIRRtYVs/KozwM4ylbyCxOwzXGKXZc3aUiU4miaLZ+k24ZGuB+NCxW1bFoQfo6UozKtjBqyS9ASiqwprSEWs7o2Qy6KI5Y27ESqpCTJ319aTwVMBpC2kGDcHFBvJ5SIrHeE2nghBANo+Tjg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=lX0LQwXU; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="lX0LQwXU" Received: from pps.filterd (m0356517.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 629GESbu1808765; Mon, 9 Mar 2026 20:24:12 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=kqSJio wyB1G6d2FyYOmEZ0o4+ZJNXp0kacpiOAoIXGw=; b=lX0LQwXUAJa0YcAO54B+J4 a3bqxKcb23mcssHGePZo/wlJtpYqWjZokB4lJzlQfxy7gECi3GXNxGNngsLZgxYe RuiS9Fih2oH3KRlAw9ZlT2CzkJPEURo/WHmUmdylBJIebbe29XiYMrk0ZrPHPU8H CTqX6BowwQ7e1vGIkBVHGDVodE/cDh3sJvXIViMtTzRvYpPqAT+45CVqpE+14SKY 4A/BkFbGLjXuqJUjQfhdagius62H11hCfppEj2a4CAaiZ2vetjjSbVESQqJ7SvXs zUAB0JTgUiBKBGikbfoViu9dmJIa8+laS8fy1m7xmTUBVV4OsKgR1PNGNL9YfZ0A == Received: from ppma13.dal12v.mail.ibm.com (dd.9e.1632.ip4.static.sl-reverse.com [50.22.158.221]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4crcyw88d3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 09 Mar 2026 20:24:12 +0000 (GMT) Received: from pps.filterd (ppma13.dal12v.mail.ibm.com [127.0.0.1]) by ppma13.dal12v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 629KIEOR025052; Mon, 9 Mar 2026 20:24:11 GMT Received: from smtprelay07.wdc07v.mail.ibm.com ([172.16.1.74]) by ppma13.dal12v.mail.ibm.com (PPS) with ESMTPS id 4cs0jjx887-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 09 Mar 2026 20:24:11 +0000 Received: from smtpav03.wdc07v.mail.ibm.com (smtpav03.wdc07v.mail.ibm.com [10.39.53.230]) by smtprelay07.wdc07v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 629KO8wJ29033214 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 9 Mar 2026 20:24:09 GMT Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DB76C5805C; Mon, 9 Mar 2026 20:24:08 +0000 (GMT) Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 16E0A58054; Mon, 9 Mar 2026 20:24:05 +0000 (GMT) Received: from [9.87.131.75] (unknown [9.87.131.75]) by smtpav03.wdc07v.mail.ibm.com (Postfix) with ESMTP; Mon, 9 Mar 2026 20:24:04 +0000 (GMT) Message-ID: <315426e8a12027dc4eb0e2a26a8fe9d448a7aa98.camel@linux.ibm.com> Subject: Re: [PATCH v8 1/1] PCI/IOV: Make pci_lock_rescan_remove() reentrant and protect sriov_add_vfs/sriov_del_vfs From: Niklas Schnelle To: "Ionut Nechita (Wind River)" , linux-pci@vger.kernel.org, bhelgaas@google.com Cc: helgaas@kernel.org, sebott@linux.ibm.com, bblock@linux.ibm.com, alifm@linux.ibm.com, julianr@linux.ibm.com, dtatulea@nvidia.com, mani@kernel.org, lukas@wunner.de, kbusch@kernel.org, ionut_n2001@yahoo.com, sunlightlinux@gmail.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, intel-xe@lists.freedesktop.org, matthew.brost@intel.com, michal.wajdeczko@intel.com, piotr.piorkowski@intel.com In-Reply-To: <20260309194920.16459-2-ionut.nechita@windriver.com> References: <20260309194920.16459-1-ionut.nechita@windriver.com> <20260309194920.16459-2-ionut.nechita@windriver.com> Autocrypt: addr=schnelle@linux.ibm.com; prefer-encrypt=mutual; keydata=mQINBGHm3M8BEAC+MIQkfoPIAKdjjk84OSQ8erd2OICj98+GdhMQpIjHXn/RJdCZLa58k /ay5x0xIHkWzx1JJOm4Lki7WEzRbYDexQEJP0xUia0U+4Yg7PJL4Dg/W4Ho28dRBROoJjgJSLSHwc 3/1pjpNlSaX/qg3ZM8+/EiSGc7uEPklLYu3gRGxcWV/944HdUyLcnjrZwCn2+gg9ncVJjsimS0ro/ 2wU2RPE4ju6NMBn5Go26sAj1owdYQQv9t0d71CmZS9Bh+2+cLjC7HvyTHKFxVGOznUL+j1a45VrVS XQ+nhTVjvgvXR84z10bOvLiwxJZ/00pwNi7uCdSYnZFLQ4S/JGMs4lhOiCGJhJ/9FR7JVw/1t1G9a UlqVp23AXwzbcoV2fxyE/CsVpHcyOWGDahGLcH7QeitN6cjltf9ymw2spBzpRnfFn80nVxgSYVG1d w75ksBAuQ/3e+oTQk4GAa2ShoNVsvR9GYn7rnsDN5pVILDhdPO3J2PGIXa5ipQnvwb3EHvPXyzakY tK50fBUPKk3XnkRwRYEbbPEB7YT+ccF/HioCryqDPWUivXF8qf6Jw5T1mhwukUV1i+QyJzJxGPh19 /N2/GK7/yS5wrt0Lwxzevc5g+jX8RyjzywOZGHTVu9KIQiG8Pqx33UxZvykjaqTMjo7kaAdGEkrHZ dVHqoPZwhCsgQARAQABtChOaWtsYXMgU2NobmVsbGUgPHNjaG5lbGxlQGxpbnV4LmlibS5jb20+iQ JXBBMBCABBAhsBBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAAhkBFiEEnbAAstJ1IDCl9y3cr+Q/Fej CYJAFAmmAWs8FCQl6sYAACgkQr+Q/FejCYJAn2g//UKzlXOgizdk0wudLooRbGzDo23ktGSPK5Oj9 9o5z6v4Jz5+qOHo5835683cqkMLM9//udA1ZcKV88LVwyfmoHChPW24cWBmOEy7RJOWCR4WeEINaO pZUGF5YOx7oKTkPs511ky2FR0Heg35754pgTuTMEpYzRXr5pNMPS8mHXcXSARFPDPaCF+uBJ9BafO L7XbpSwKRttePsWAlPHbSbloeDApBfHUhcF/pbuM9GNs+c/8V9NK+SwwqNK214t7jaSq9k+19/hfE jvU45nbiYQM4VqGCelxVFRWol93JnwPFp/JaMgxgV1VYFH9Ijtgh+qNVVBqO8bbTjioFKy1bHdprN 9GyPLDxoaI/lBg+5CwKewzazUjFd0xaqZbTXSgNK4ev/IuNI3qZV8tpvZZWwIgZU1K0Bhplt8Sku+ O9Yl2H54erq9zuzwXjqBJtoW0+MaKbe+1gZ/v2/AVE2VeQMugPUWDg+2bpJaApRkeA4xQ9XfeW6Bp It7xYrwwbVhQtWRC0sRh+QNlU9HI28wPSnLWn7HFBeWupaIrxSp4IEL3eHUn8xv4aA8lpdNsHXD/X vqOSUwy5jlTPTlemvwaC9mNHagNdVXng8C6+hxiDLhZ6xH2P4qNHTKmjW61NsdF6Y/HfWP+lmbi8/ 474UNCltDt/fP01ajqogfWZKFymoH0O0KU5pa2xhcyBTY2huZWxsZSA8bmlrbGFzLnNjaG5lbGxlQ GlibS5jb20+iQJUBBMBCAA+AhsBBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAFiEEnbAAstJ1IDCl9y 3cr+Q/FejCYJAFAmmAWusFCQl6sYAACgkQr+Q/FejCYJAtIw//WmQW/Z+SLdfrlDH5J2bvixzFNnO TOvp8uM8vcNZsxZwPXem4AeCXHayCqipxpa0iXWufEIvdMxkBxWvvM//V+rTUgQnJe6nhDxfLGklx 5Mb2H+K/ndS73ElCuA30MPYq7mHr8i3gEmi2ZFX1W47JecJ8hno/DQxhHRG7bd+GFsiKCbsjLWXNq s/VaAK9uyOTQx7m6/2nR8L+Mvl1BrRXwkj7Qp0qxfQSd4r+IVNBzNFOcrGagBqsyHrN7Is7IICktH 9VFl/G8P+hfviHQLnlxw9ltzpM1Dy6N1+BM3kbqD59gX+L6wqiLJI42eh+SHCiy35FvD3AFlYx4jZ MWE6qIgFnbwcL1kvcA7nnwfr3ZizCYPm8e334xXxslXBoRGsvjXSbAeAyZo2dvJXffNHdcDdUbJSl CfOixNGGKiQvs00X9ekfq9WmmRFvmYHu/m3lg1OXnMjFFIO41O51ZdhbEYJiqZEki7jA8Hd9xuWwQ nFDHhacU3xxivZ4BKQGQc+4XZ3yp/q6+7ux9prepRy/LeRyoaAmE67oxEsAgj+qyA3Tfy5nRTDdRQ E//gpaIt9H1VEx+68dRWHroxBQeozpnFPi25AlX3k4/EtVZjcItPWgE9iru1qT4DH3BBrz7Kd1zUw NnQC77zDJyZD2WUj1E+5bftO0aeE+7HZXj3tM/ea0K05pa2xhcyBTY2huZWxsZSA8bmlrbGFzLnNj aG5lbGxlQGdtYWlsLmNvbT6JAlQEEwEIAD4CGwEFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AWIQSds ACy0nUgMKX3Ldyv5D8V6MJgkAUCaYBa6wUJCXqxgAAKCRCv5D8V6MJgkF/TEACOY2kL4NGFIbWeM5 TUhatxqe8c3RT6jvNjq32CkvaK/cSZzBkS0smddyOzxt2WnsvMgkr9cM7P+CevoMwhT3e0lgQbqBD /vXZJjWKddC+iKXeqWkjMVcgCOsWNZ7PWEzRUT5X1AEFq2zzxQAQ/bCWEYNqIbHN4b6G1Wk+2Y598 +KypZ3FS0bwiItnPQOWzOOqJCGxDxaEUuXFx4ah8HtVdtIev8jPS/5uzQO9iG2vZQUWeMEYZtfMHW sbFWqo2A3lxB+KPzNIYFhul4Lyx1CwvKUAGSHOx7FZuc2xI5DYt/Wdh2QyKFYr7xVzv3uwJjeS1+3 6gvyB7DJaQuY+PziNPv4GPr5wy0cRkJ6Ps15fgC6y6wNwoNdNXKlwiuclIsBzJKa7A0pZMIfpCpIJ bEHP7oy3drBRAhIrBx7Lx1lyqqodDqc+ok5IQ5WcKG/TOrH732mTmJX6fxYTiCVxcU4WLJSNZbrZ/ pjF0AWXs7E+onAkQy6RLg/XU1iiU5QdMvug+fTA6TpPSUMdujWtGWUt3/4nC+69AVc8tXtRQTZ7gP t7uIcQFwPqUuJGS26vl0w/6dIABQAyU9acvE3adCZra+/PBKFZi/yxT1WgV1T2mexKSWwQgLcR57J Yp5oWnQRgi/S6fAoskIWkp9UVcfAQPY0p45NwO5cZR9/g06JZmyrQhTmlrbGFzIFNjaG5lbGxlIDx uaWtzQGtlcm5lbC5vcmc+iQJUBBMBCAA+AhsBBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAFiEEnbAA stJ1IDCl9y3cr+Q/FejCYJAFAmmAWusFCQl6sYAACgkQr+Q/FejCYJAz4A/9F+dMhzu7YonagL4qh WDz5IpRD4vzYKOBZ+qwYp1ugJz1BIUppN9i68HKoS4ARfgP97Sv9GpOy9g7L0lymH2MPF8hRPK0Yn 7DKIkeu/r28YWEoWfoVm5reC+gpxMgmxBz4JScE4f6xfa7+Nw0bbTDl+nxftJD7lf/dTiruNJsXph HQnZ5wPXmxeH6XVJikfpyrGe8iJZALbtHtjlx6Omu7NvRGikenB8trrWS5W0F60ZdbqH1HdmDDcrZ pDq6LtAARHK5tGRm0SK6sZpKe3nULFeeCt7T/edk2FC6KVh4sL1jw1kyceX4DjiMffqYBPrhK5gz5 cDIixLBF9C6Wt1ObvuDBrIQf1/3q6EZrUrUuf6qtaXDMuC6cSlShm47qaPEvVYh67O9JZQ7vzvaea UI74DJUb8Pjnz7mTOmMOzsS1gUhCue4n2YSSM6ythioCGb/3bgMGTpuer3JhvZG5s5uKD9yyj8s8x 35qJkCFfjmjVx9s3vSUS48X+cUpYcMispErKzFu7C0YgKoxvJ4XTfXlDBiMFMPYcN67hsb2jeYHVJ wzE+fIZiDx9JLh1oQW2krwjweisE+3glOaKXZKi0fBtkxyH41iemLtLNYZRJopv6ykdl3hiI+Nh+a 3FZJPTo/OpqchMm8XIeDxC4NFFiPMpyLeYzIxO7eZpiGrAjVTE= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Mon, 09 Mar 2026 21:23:03 +0100 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzA5MDE3OCBTYWx0ZWRfXw6WLO3Rdu2zG jkPViaz4YUphZySCq6R5sIxQYjlBxkXcn5gKmROUblcBUhBrKkGEw1Y0NK/R/7s/9fn6atN7gc0 TIz5atFVTRA0mYUJlZ8nVbQsT3K5opat2GU4F6RbjClgMHbZB+z2iQNa6N2aJ4Otnk2Rxf0q2Dx RGvZq0lWHCjiYRjhA/gLX821ugwwB/1A7FR2mVKY6KK3OMKQ6RoLfLoymd3RabIav9WIbfe/Wiq 6bJS8xcUDr0FkoJdFjbiShkpmpTZvbPYZKaIlBn9pkyXpIsiKzuejyldr3moSGS1bMgahjlM2hP KFNpisjhozFoPelT+5cuz+I/gtTWIJZmkJVpZk8RIgyGIvV8CVGQ+wHuPdhhLaOzkIh6REv4unR lFh+hqqItx6Uk4LPK9gAkt7Rc48ObvWp0lP0SRuT34D201kZ+x2OEBs+wjXF2oT6MgqrEz1vZwh JSO70VxkoyLg59e6gLw== X-Authority-Analysis: v=2.4 cv=QaVrf8bv c=1 sm=1 tr=0 ts=69af2c6c cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=CjxXgO3LAAAA:8 a=t7CeM3EgAAAA:8 a=xHlSXgK-8sZQpV_rmxkA:9 a=QEXdDO2ut3YA:10 a=FdTzh2GWekK77mhwV6Dw:22 X-Proofpoint-GUID: JDtsKQqmY9IEdc8aJA4BacB_gATckoaq X-Proofpoint-ORIG-GUID: BV5qGQcP7bpFvkBPz6ynzCjJxDcUPR7j X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-09_05,2026-03-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 spamscore=0 impostorscore=0 clxscore=1011 adultscore=0 bulkscore=0 lowpriorityscore=0 priorityscore=1501 suspectscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2602130000 definitions=main-2603090178 On Mon, 2026-03-09 at 21:49 +0200, Ionut Nechita (Wind River) wrote: > After reverting commit 05703271c3cd ("PCI/IOV: Add PCI rescan-remove > locking when enabling/disabling SR-IOV") and moving the lock to > sriov_numvfs_store(), the path through driver .remove() (e.g. rmmod, > or manual unbind) that calls pci_disable_sriov() directly remains > unprotected against concurrent hotplug events. This affects any SR-IOV > capable driver that calls pci_disable_sriov() from its .remove() > callback (i40e, ice, mlx5, bnxt, etc.). >=20 > On s390, platform-generated hot-unplug events for VFs can race with > sriov_del_vfs() when a PF driver is being unloaded. The platform event > handler takes pci_rescan_remove_lock, but sriov_del_vfs() does not, > leading to double removal and list corruption. >=20 > We cannot use a plain mutex_lock() here because sriov_del_vfs() may also > be called from paths that already hold pci_rescan_remove_lock (e.g. > remove_store -> pci_stop_and_remove_bus_device_locked, or > sriov_numvfs_store with the lock taken by the previous patch). Using > mutex_lock() in those cases would deadlock. >=20 > Make pci_lock_rescan_remove() itself reentrant using mutex_get_owner() > and a reentrant depth counter, as suggested by Lukas Wunner and > Benjamin Block, since these recursive locking scenarios exist elsewhere > in the PCI subsystem: > - If the lock is already held by the current task (checked via > mutex_get_owner()): increments the reentrant counter and returns > without re-acquiring, avoiding deadlock. > - If the lock is held by another task: blocks until the lock is > released, providing complete serialization. > - If the lock is not held: acquires the mutex normally. >=20 > pci_unlock_rescan_remove() decrements the reentrant counter if it is > non-zero, otherwise releases the mutex. >=20 > This approach keeps the API unchanged: callers simply pair lock/unlock > calls without needing to track any return value or use separate > reentrant variants. >=20 > Add pci_lock_rescan_remove()/pci_unlock_rescan_remove() calls to > sriov_add_vfs() and sriov_del_vfs() to protect VF addition and > removal against concurrent hotplug events. >=20 > Fixes: 18f9e9d150fc ("PCI/IOV: Factor out sriov_add_vfs()") > Cc: stable@vger.kernel.org > Suggested-by: Lukas Wunner > Suggested-by: Benjamin Block > Reviewed-by: Benjamin Block > Tested-by: Benjamin Block > Signed-off-by: Ionut Nechita > Signed-off-by: Ionut Nechita > --- Sorry, bad timing on my part, I had just sent my reply[0] for v7 before I looked again at my Inbox. Seeing as the code hasn't changed it still applies. Also I forgot to add that I also tested this on s390. My testing was in combination with Benjamin's series[1] because otherwise there are still interfering issues. Tested-by: Niklas Schnelle # s390 Thanks, Niklas [0] https://lore.kernel.org/linux-pci/eea6652a968a9ad772eaa8e161e165e4414b1800.= camel@linux.ibm.com/ [1] https://lore.kernel.org/linux-pci/cover.1772815642.git.bblock@linux.ibm.com= /