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Wed, 24 Sep 2025 18:06:32 +0000 (GMT) Message-ID: <48360cde-81d9-4161-8c32-0029e193c685@linux.ibm.com> Date: Wed, 24 Sep 2025 11:06:22 -0700 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] PCI: Add lockdep assertion in pci_stop_and_remove_bus_device() To: Niklas Schnelle , Bjorn Helgaas , Lukas Wunner Cc: Keith Busch , Gerd Bayer , Matthew Rosato , Benjamin Block , Halil Pasic , Julian Ruess , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250826-pci_fix_sriov_disable-v1-0-2d0bc938f2a3@linux.ibm.com> <20250826-pci_fix_sriov_disable-v1-2-2d0bc938f2a3@linux.ibm.com> Content-Language: en-US From: Farhan Ali In-Reply-To: <20250826-pci_fix_sriov_disable-v1-2-2d0bc938f2a3@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=FrEF/3rq c=1 sm=1 tr=0 ts=68d4332c cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=yJojWOMRYYMA:10 a=VnNF1IyMAAAA:8 a=F53kh5m_LVtqdGsIIDMA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: HGLcPrf4wuJDEogZpyRV4eoNNGqNiWsr X-Proofpoint-GUID: HGLcPrf4wuJDEogZpyRV4eoNNGqNiWsr X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwOTE5MDIyNCBTYWx0ZWRfXyjh1glDtSlFL SUiwmzbNBrpRieCE/v0oBtzSv6UcUsRn0XcVai75PT68KbYRhiKBzFDpZEMTxd+VdKYaG0uviKQ cnfu9go0Kb7gBZz952rJgfgb9aX2C/pSrrsGxYeBQIqLQt4i7jQvBTv06T0R5kZvETANfbQP+no 2LxkxebggD4JB00JrRrftTT/IDsWG0iQT+gGpgk4AkOeqds2qFd1df58/fmxyge7MFB85DI8m8o 12oTfDlwGy+12fH/8dfyA4sFqnQnAaxUDMg5+WVb+CDknHi+phNORXvinquNS8yhIS1GRLJAGYI 8BxxD0GZhRPP9T4OvZwW/xKTS05e0WNz1j7F4euaDoXCePjd0gxdTjM4KdrHVSTe6/qwFHJMFOy g246xgk4 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-09-24_04,2025-09-24_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 priorityscore=1501 malwarescore=0 adultscore=0 clxscore=1011 impostorscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2509190224 On 8/26/2025 1:52 AM, Niklas Schnelle wrote: > Removing a PCI devices requires holding pci_rescan_remove_lock. Prompted > by this being missed in sriov_disable() and going unnoticed since its > inception add a lockdep assert so this doesn't get missed again in the > future. > > Reviewed-by: Benjamin Block > Signed-off-by: Niklas Schnelle > --- > drivers/pci/pci.h | 2 ++ > drivers/pci/probe.c | 2 +- > drivers/pci/remove.c | 1 + > 3 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h > index 34f65d69662e9f61f0c489ec58de2ce17d21c0c6..1ad2e3ab147f3b2c42b3257e4f366fc5e424ede3 100644 > --- a/drivers/pci/pci.h > +++ b/drivers/pci/pci.h > @@ -84,6 +84,8 @@ struct pcie_tlp_log; > extern const unsigned char pcie_link_speed[]; > extern bool pci_early_dump; > > +extern struct mutex pci_rescan_remove_lock; > + > bool pcie_cap_has_lnkctl(const struct pci_dev *dev); > bool pcie_cap_has_lnkctl2(const struct pci_dev *dev); > bool pcie_cap_has_rtctl(const struct pci_dev *dev); > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index f41128f91ca76ab014ad669ae84a53032c7c6b6b..2b35bb39ab0366bbf86b43e721811575b9fbcefb 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -3469,7 +3469,7 @@ EXPORT_SYMBOL_GPL(pci_rescan_bus); > * pci_rescan_bus(), pci_rescan_bus_bridge_resize() and PCI device removal > * routines should always be executed under this mutex. > */ > -static DEFINE_MUTEX(pci_rescan_remove_lock); > +DEFINE_MUTEX(pci_rescan_remove_lock); > > void pci_lock_rescan_remove(void) > { > diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c > index 445afdfa6498edc88f1ef89df279af1419025495..0b9a609392cecba36a818bc496a0af64061c259a 100644 > --- a/drivers/pci/remove.c > +++ b/drivers/pci/remove.c > @@ -138,6 +138,7 @@ static void pci_remove_bus_device(struct pci_dev *dev) > */ > void pci_stop_and_remove_bus_device(struct pci_dev *dev) > { > + lockdep_assert_held(&pci_rescan_remove_lock); > pci_stop_bus_device(dev); > pci_remove_bus_device(dev); > } We also have the function pci_stop_and_remove_bus_device_locked() as Gerd mentioned, so is pci_stop_and_remove_bus_device meant to be called without the rescan_remove_lock held? This is a little confusing as we shouldn't be adding/removing from the bus without the lock AFAIU, but maybe I am missing something? Thanks Farhan