From kaneshige.kenji@jp.fujitsu.com Thu Feb 21 13:36:36 2008 From: Kenji Kaneshige Date: Thu, 21 Feb 2008 15:24:16 +0900 Subject: PCI: Fix wrong reference counter check for proc_dir_entry To: linux-pci@atrey.karlin.mff.cuni.cz Cc: Greg KH Message-ID: <47BD1910.2020202@jp.fujitsu.com> Fix wrong counter check for proc_dir_entry in pci_proc_detach_device(). The pci_proc_detach_device() returns with -EBUSY before calling remove_proc_entry() if the reference counter of proc_dir_entry is not 0. But this check is wrong and pci_proc_detach_device() always fails because the reference counter of proc_dir_entry is initialized with 1 at creating time and decremented in remove_proc_entry(). This bug cause strange behaviour as followings: - Accessing /proc/bus/pci/XXXX/YY file after hot-removing pci adapter card causes kernel panic. - Repeating hot-add/hot-remove of pci adapter card increases files with the same name under /proc/bus/pci/XXXX/ directory. For example: # pwd /proc/bus/pci/0002:09 # ls 01.0 # for i in `seq 5` > do > echo 0 > /sys/bus/pci/slots/0009_0032/power > echo 1 > /sys/bus/pci/slots/0009_0032/power > done # ls 01.0 01.0 01.0 01.0 01.0 01.0 The pci_proc_detach_device() should check if the reference counter is not larger than 1 instead. Signed-off-by: Kenji Kaneshige Signed-off-by: Greg Kroah-Hartman --- drivers/pci/proc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -422,7 +422,7 @@ int pci_proc_detach_device(struct pci_de struct proc_dir_entry *e; if ((e = dev->procent)) { - if (atomic_read(&e->count)) + if (atomic_read(&e->count) > 1) return -EBUSY; remove_proc_entry(e->name, dev->bus->procdir); dev->procent = NULL;