[PATCH v2 2/6] PCI/proc: Serialize config inode size updates

proc_bus_pci_write() calls i_size_write() without serializing concurrent
writers. On 32-bit SMP systems, concurrent updates can corrupt
i_size_seqcount and make later i_size_read() calls spin indefinitely.

Protect the inode size update with the inode lock, as required by
i_size_write().

Fixes: ecb3908046ce ("pci: write file size to inode on proc bus file write")
Signed-off-by: Ziming Du <[email protected]>
---
 drivers/pci/proc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index cad749924dd89..ec2338c1e667e 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -181,7 +181,9 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,
 	pci_config_pm_runtime_put(dev);
 
 	*ppos = pos;
+	inode_lock(ino);
 	i_size_write(ino, dev->cfg_size);
+	inode_unlock(ino);
 	return nbytes;
 }
 
-- 
2.43.0