From 64a07bd82ed526d813b64b0957543eef55bdf9c0 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Sun, 26 Mar 2006 01:36:55 -0800 Subject: [PATCH] protect remove_proc_entry It has been discovered that the remove_proc_entry has a race in the removing of entries in the proc file system that are siblings. There's no protection around the traversing and removing of elements that belong in the same subdirectory. This subdirectory list is protected in other areas by the BKL. So the BKL was at first used to protect this area too, but unfortunately, remove_proc_entry may be called with spinlocks held. The BKL may schedule, so this was not a solution. The final solution was to add a new global spin lock to protect this list, called proc_subdir_lock. This lock now protects the list in remove_proc_entry, and I also went around looking for other areas that this list is modified and added this protection there too. Care must be taken since these locations call several functions that may also schedule. Since I don't see any location that these functions that modify the subdirectory list are called by interrupts, the irqsave/restore versions of the spin lock was _not_ used. Signed-off-by: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/proc_fs.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux') diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index aa6322d4519..6b12b0f661b 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -4,6 +4,7 @@ #include #include #include +#include #include /* @@ -92,6 +93,8 @@ extern struct proc_dir_entry *proc_bus; extern struct proc_dir_entry *proc_root_driver; extern struct proc_dir_entry *proc_root_kcore; +extern spinlock_t proc_subdir_lock; + extern void proc_root_init(void); extern void proc_misc_init(void); -- cgit v1.2.3