Re: [PATCH v6] PCI/pcie: Add PCIe Lane Margining at Receiver (LMR) support
From: Dan Carpenter
Date: Wed Sep 09 2026 - 07:04:14 EST
Hi Priyank,
kernel test robot noticed the following build warnings:
url: https://github.com/intel-lab-lkp/linux/commits/Priyank-Rathod/PCI-pcie-Add-PCIe-Lane-Margining-at-Receiver-LMR-support/20260824-223812
base: 0f23d56f17fdfc7db69d51f64c8b91bbab947aa9
patch link: https://lore.kernel.org/r/20260824-pcie-lmt-v6-1-bab4ce233fa5%40google.com
patch subject: [PATCH v6] PCI/pcie: Add PCIe Lane Margining at Receiver (LMR) support
config: powerpc64-randconfig-r073-20260826 (https://download.01.org/0day-ci/archive/20260826/202608260405.gHL6gOJf-lkp@xxxxxxxxx/config)
compiler: powerpc64-linux-gcc (GCC) 15.2.0
smatch: v0.5.0-9187-g5189e3fb
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Reported-by: Dan Carpenter <error27@xxxxxxxxx>
| Closes: https://lore.kernel.org/r/202608260405.gHL6gOJf-lkp@xxxxxxxxx/
smatch warnings:
drivers/pci/pcie/margin.c:1005 pci_lmr_exit() warn: variable dereferenced before check 'dev' (see line 1003)
drivers/pci/pcie/margin.c:1020 pci_suspend_lmr() warn: variable dereferenced before check 'dev' (see line 1018)
drivers/pci/pcie/margin.c:1056 pci_reset_lmr() warn: variable dereferenced before check 'dev' (see line 1054)
vim +/dev +1005 drivers/pci/pcie/margin.c
ecb76f560cf217 Priyank Rathod 2026-08-24 1001 void pci_lmr_exit(struct pci_dev *dev)
ecb76f560cf217 Priyank Rathod 2026-08-24 1002 {
ecb76f560cf217 Priyank Rathod 2026-08-24 @1003 struct pci_margin_dev *mdev = dev->lmr;
^^^^^
Dereference
ecb76f560cf217 Priyank Rathod 2026-08-24 1004
ecb76f560cf217 Priyank Rathod 2026-08-24 @1005 if (!dev || !mdev)
^^^^
This check is too late. It can likely be removed. The other warnings
are the same.
ecb76f560cf217 Priyank Rathod 2026-08-24 1006 return;
ecb76f560cf217 Priyank Rathod 2026-08-24 1007
ecb76f560cf217 Priyank Rathod 2026-08-24 1008 pci_suspend_lmr(dev);
ecb76f560cf217 Priyank Rathod 2026-08-24 1009
ecb76f560cf217 Priyank Rathod 2026-08-24 1010 pci_margin_debugfs_remove(mdev);
ecb76f560cf217 Priyank Rathod 2026-08-24 1011 mutex_destroy(&mdev->lock);
ecb76f560cf217 Priyank Rathod 2026-08-24 1012 kfree(mdev);
ecb76f560cf217 Priyank Rathod 2026-08-24 1013 dev->lmr = NULL;
ecb76f560cf217 Priyank Rathod 2026-08-24 1014 }
ecb76f560cf217 Priyank Rathod 2026-08-24 1015
ecb76f560cf217 Priyank Rathod 2026-08-24 1016 void pci_suspend_lmr(struct pci_dev *dev)
ecb76f560cf217 Priyank Rathod 2026-08-24 1017 {
ecb76f560cf217 Priyank Rathod 2026-08-24 @1018 struct pci_margin_dev *mdev = dev->lmr;
ecb76f560cf217 Priyank Rathod 2026-08-24 1019
ecb76f560cf217 Priyank Rathod 2026-08-24 @1020 if (!dev || !mdev)
ecb76f560cf217 Priyank Rathod 2026-08-24 1021 return;
ecb76f560cf217 Priyank Rathod 2026-08-24 1022
ecb76f560cf217 Priyank Rathod 2026-08-24 1023 guard(mutex)(&mdev->lock);
ecb76f560cf217 Priyank Rathod 2026-08-24 1024 pci_lmr_disable_locked(mdev);
ecb76f560cf217 Priyank Rathod 2026-08-24 1025 }
ecb76f560cf217 Priyank Rathod 2026-08-24 1026
ecb76f560cf217 Priyank Rathod 2026-08-24 1027 static void pci_lmr_reset_software_state_locked(struct pci_margin_dev *mdev)
ecb76f560cf217 Priyank Rathod 2026-08-24 1028 {
ecb76f560cf217 Priyank Rathod 2026-08-24 1029 struct pci_dev *dev;
ecb76f560cf217 Priyank Rathod 2026-08-24 1030 int i;
ecb76f560cf217 Priyank Rathod 2026-08-24 1031
ecb76f560cf217 Priyank Rathod 2026-08-24 1032 if (!mdev)
ecb76f560cf217 Priyank Rathod 2026-08-24 1033 return;
ecb76f560cf217 Priyank Rathod 2026-08-24 1034
ecb76f560cf217 Priyank Rathod 2026-08-24 1035 lockdep_assert_held(&mdev->lock);
ecb76f560cf217 Priyank Rathod 2026-08-24 1036
ecb76f560cf217 Priyank Rathod 2026-08-24 1037 if (!mdev->enabled)
ecb76f560cf217 Priyank Rathod 2026-08-24 1038 return;
ecb76f560cf217 Priyank Rathod 2026-08-24 1039
ecb76f560cf217 Priyank Rathod 2026-08-24 1040 dev = mdev->dev;
ecb76f560cf217 Priyank Rathod 2026-08-24 1041
ecb76f560cf217 Priyank Rathod 2026-08-24 1042 for (i = 0; i < mdev->num_lanes; i++) {
ecb76f560cf217 Priyank Rathod 2026-08-24 1043 mdev->lanes[i].timing_val = 0;
ecb76f560cf217 Priyank Rathod 2026-08-24 1044 mdev->lanes[i].voltage_val = 0;
ecb76f560cf217 Priyank Rathod 2026-08-24 1045 }
ecb76f560cf217 Priyank Rathod 2026-08-24 1046
ecb76f560cf217 Priyank Rathod 2026-08-24 1047 pci_lmr_restore_aspm(mdev);
ecb76f560cf217 Priyank Rathod 2026-08-24 1048 pm_runtime_put_sync(&dev->dev);
ecb76f560cf217 Priyank Rathod 2026-08-24 1049 mdev->enabled = false;
ecb76f560cf217 Priyank Rathod 2026-08-24 1050 }
ecb76f560cf217 Priyank Rathod 2026-08-24 1051
ecb76f560cf217 Priyank Rathod 2026-08-24 1052 void pci_reset_lmr(struct pci_dev *dev)
ecb76f560cf217 Priyank Rathod 2026-08-24 1053 {
ecb76f560cf217 Priyank Rathod 2026-08-24 @1054 struct pci_margin_dev *mdev = dev->lmr;
ecb76f560cf217 Priyank Rathod 2026-08-24 1055
ecb76f560cf217 Priyank Rathod 2026-08-24 @1056 if (!dev || !mdev)
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