The assertions work as well as the comment to inform developers about
locking expectations.
Additionally they are validated by lockdep at runtime, making sure the
expectations are met.
Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
---
Tested against the sysctl selftests and normal desktop usage.
---
fs/proc/proc_sysctl.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index b1c2c0b82116..1d9d789fbd3e 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -17,6 +17,7 @@
#include <linux/bpf-cgroup.h>
#include <linux/mount.h>
#include <linux/kmemleak.h>
+#include <linux/lockdep.h>
#include "internal.h"
#define list_for_each_table_entry(entry, header) \
@@ -104,7 +105,6 @@ static int namecmp(const char *name1, int len1, const char *name2, int len2)
return cmp;
}
-/* Called under sysctl_lock */
static struct ctl_table *find_entry(struct ctl_table_header **phead,
struct ctl_dir *dir, const char *name, int namelen)
{
@@ -112,6 +112,8 @@ static struct ctl_table *find_entry(struct ctl_table_header **phead,
struct ctl_table *entry;
struct rb_node *node = dir->root.rb_node;
+ lockdep_assert_held(&sysctl_lock);
+
while (node)
{
struct ctl_node *ctl_node;
@@ -258,18 +260,20 @@ static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
return err;
}
-/* called under sysctl_lock */
static int use_table(struct ctl_table_header *p)
{
+ lockdep_assert_held(&sysctl_lock);
+
if (unlikely(p->unregistering))
return 0;
p->used++;
return 1;
}
-/* called under sysctl_lock */
static void unuse_table(struct ctl_table_header *p)
{
+ lockdep_assert_held(&sysctl_lock);
+
if (!--p->used)
if (unlikely(p->unregistering))
complete(p->unregistering);
@@ -280,9 +284,11 @@ static void proc_sys_invalidate_dcache(struct ctl_table_header *head)
proc_invalidate_siblings_dcache(&head->inodes, &sysctl_lock);
}
-/* called under sysctl_lock, will reacquire if has to wait */
static void start_unregistering(struct ctl_table_header *p)
{
+ /* will reacquire if has to wait */
+ lockdep_assert_held(&sysctl_lock);
+
/*
* if p->used is 0, nobody will ever touch that entry again;
* we'll eliminate all paths to it before dropping sysctl_lock
---
base-commit: 27b31deb900dfcec60820d8d3e48f6de9ae9a18e
change-id: 20240629-sysctl-lockdep-26c90b73a786
Best regards,
--
Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
