From: Ryo Takakura <ryotkkr98@xxxxxxxxx> 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 has been made a raw_spinlock_t for this purpose. A spinlock_t becomes a sleeping lock on PREEMPT_RT can not 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. [bigeasy: Reword commit message.] Signed-off-by: Ryo Takakura <ryotkkr98@xxxxxxxxx> Tested-by: Luis Claudio R. Goncalves <lgoncalv@xxxxxxxxxx> Acked-by: Luis Claudio R. Goncalves <lgoncalv@xxxxxxxxxx> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> --- Changes since v3 https://lore.kernel.org/all/20241219014549.24427-1-ryotkkr98@xxxxxxxxx/ - Repost with updated changelog. Changes since v2 https://lore.kernel.org/lkml/20241218115951.83062-1-ryotkkr98@xxxxxxxxx/ - In case if CONFIG_PCI_LOCKLESS_CONFIG is set, vmd_pci_read/write() still neeed cfg_lock for their serialization. So instead of removing it, convert it to raw spinlock. v1: https://lore.kernel.org/lkml/20241215141321.383144-1-ryotkkr98@xxxxxxxxx/ 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 9d9596947350f..94ceec50a2b94 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; @@ -391,7 +391,7 @@ 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); @@ -406,7 +406,7 @@ 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; } @@ -426,7 +426,7 @@ 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); @@ -444,7 +444,7 @@ 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; } @@ -1009,7 +1009,7 @@ 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) -- 2.47.2
