6.6-stable review patch. If anyone has any objections, please let me know.
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From: Ryo Takakura ryotkkr98@gmail.com
[ Upstream commit 18056a48669a040bef491e63b25896561ee14d90 ]
The access to the PCI config space via pci_ops::read and pci_ops::write is a low-level hardware access. The functions can be accessed with disabled interrupts even on PREEMPT_RT. The pci_lock is a raw_spinlock_t for this purpose.
A spinlock_t becomes a sleeping lock on PREEMPT_RT, so it cannot be acquired with disabled interrupts. The vmd_dev::cfg_lock is accessed in the same context as the pci_lock.
Make vmd_dev::cfg_lock a raw_spinlock_t type so it can be used with interrupts disabled.
This was reported as:
BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 Call Trace: rt_spin_lock+0x4e/0x130 vmd_pci_read+0x8d/0x100 [vmd] pci_user_read_config_byte+0x6f/0xe0 pci_read_config+0xfe/0x290 sysfs_kf_bin_read+0x68/0x90
Signed-off-by: Ryo Takakura ryotkkr98@gmail.com Tested-by: Luis Claudio R. Goncalves lgoncalv@redhat.com Acked-by: Luis Claudio R. Goncalves lgoncalv@redhat.com [bigeasy: reword commit message] Signed-off-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Tested-off-by: Luis Claudio R. Goncalves lgoncalv@redhat.com Link: https://lore.kernel.org/r/20250218080830.ufw3IgyX@linutronix.de [kwilczynski: commit log] Signed-off-by: Krzysztof Wilczyński kwilczynski@kernel.org [bhelgaas: add back report info from https://lore.kernel.org/lkml/20241218115951.83062-1-ryotkkr98@gmail.com/] Signed-off-by: Bjorn Helgaas bhelgaas@google.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/controller/vmd.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c index 5ff2066aa5164..dfa222e02c4da 100644 --- a/drivers/pci/controller/vmd.c +++ b/drivers/pci/controller/vmd.c @@ -125,7 +125,7 @@ struct vmd_irq_list { struct vmd_dev { struct pci_dev *dev;
- spinlock_t cfg_lock; + raw_spinlock_t cfg_lock; void __iomem *cfgbar;
int msix_count; @@ -402,7 +402,7 @@ static int vmd_pci_read(struct pci_bus *bus, unsigned int devfn, int reg, if (!addr) return -EFAULT;
- spin_lock_irqsave(&vmd->cfg_lock, flags); + raw_spin_lock_irqsave(&vmd->cfg_lock, flags); switch (len) { case 1: *value = readb(addr); @@ -417,7 +417,7 @@ static int vmd_pci_read(struct pci_bus *bus, unsigned int devfn, int reg, ret = -EINVAL; break; } - spin_unlock_irqrestore(&vmd->cfg_lock, flags); + raw_spin_unlock_irqrestore(&vmd->cfg_lock, flags); return ret; }
@@ -437,7 +437,7 @@ static int vmd_pci_write(struct pci_bus *bus, unsigned int devfn, int reg, if (!addr) return -EFAULT;
- spin_lock_irqsave(&vmd->cfg_lock, flags); + raw_spin_lock_irqsave(&vmd->cfg_lock, flags); switch (len) { case 1: writeb(value, addr); @@ -455,7 +455,7 @@ static int vmd_pci_write(struct pci_bus *bus, unsigned int devfn, int reg, ret = -EINVAL; break; } - spin_unlock_irqrestore(&vmd->cfg_lock, flags); + raw_spin_unlock_irqrestore(&vmd->cfg_lock, flags); return ret; }
@@ -1020,7 +1020,7 @@ static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id) if (features & VMD_FEAT_OFFSET_FIRST_VECTOR) vmd->first_vec = 1;
- spin_lock_init(&vmd->cfg_lock); + raw_spin_lock_init(&vmd->cfg_lock); pci_set_drvdata(dev, vmd); err = vmd_enable_domain(vmd, features); if (err)