Commit-ID: 7dc52157982ab771f40e3c0b7dc55b954c3c2d19
Gitweb: http://git.kernel.org/tip/7dc52157982ab771f40e3c0b7dc55b954c3c2d19
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 22 Feb 2010 17:04:52 -0800
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 25 Feb 2010 10:34:48 +0100
vfs: Apply lockdep-based checking to rcu_dereference() uses
Add lockdep-ified RCU primitives to alloc_fd(), files_fdtable()
and fcheck_files().
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: laijs@xxxxxxxxxxxxxx
Cc: dipankar@xxxxxxxxxx
Cc: mathieu.desnoyers@xxxxxxxxxx
Cc: josh@xxxxxxxxxxxxxxxx
Cc: dvhltc@xxxxxxxxxx
Cc: niv@xxxxxxxxxx
Cc: peterz@xxxxxxxxxxxxx
Cc: rostedt@xxxxxxxxxxx
Cc: Valdis.Kletnieks@xxxxxx
Cc: dhowells@xxxxxxxxxx
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
LKML-Reference: <1266887105-1528-8-git-send-email-paulmck@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
fs/file.c | 2 +-
fs/proc/array.c | 2 ++
fs/proc/base.c | 6 +++++-
include/linux/fdtable.h | 8 ++++++--
4 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/fs/file.c b/fs/file.c
index 87e1290..38039af 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -478,7 +478,7 @@ repeat:
error = fd;
#if 1
/* Sanity check */
- if (rcu_dereference(fdt->fd[fd]) != NULL) {
+ if (rcu_dereference_raw(fdt->fd[fd]) != NULL) {
printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);
rcu_assign_pointer(fdt->fd[fd], NULL);
}
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 13b5d07..18e20fe 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -270,7 +270,9 @@ static inline void task_sig(struct seq_file *m, struct task_struct *p)
blocked = p->blocked;
collect_sigign_sigcatch(p, &ignored, &caught);
num_threads = atomic_read(&p->signal->count);
+ rcu_read_lock(); /* FIXME: is this correct? */
qsize = atomic_read(&__task_cred(p)->user->sigpending);
+ rcu_read_unlock();
qlim = p->signal->rlim[RLIMIT_SIGPENDING].rlim_cur;
unlock_task_sighand(p, &flags);
}
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 58324c2..623e2ff 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1095,8 +1095,12 @@ static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
if (!capable(CAP_AUDIT_CONTROL))
return -EPERM;
- if (current != pid_task(proc_pid(inode), PIDTYPE_PID))
+ rcu_read_lock();
+ if (current != pid_task(proc_pid(inode), PIDTYPE_PID)) {
+ rcu_read_unlock();
return -EPERM;
+ }
+ rcu_read_unlock();
if (count >= PAGE_SIZE)
count = PAGE_SIZE - 1;
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index a2ec74b..144412f 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -57,7 +57,11 @@ struct files_struct {
struct file * fd_array[NR_OPEN_DEFAULT];
};
-#define files_fdtable(files) (rcu_dereference((files)->fdt))
+#define files_fdtable(files) \
+ (rcu_dereference_check((files)->fdt, \
+ rcu_read_lock_held() || \
+ lockdep_is_held(&(files)->file_lock) || \
+ atomic_read(&files->count) == 1))
struct file_operations;
struct vfsmount;
@@ -78,7 +82,7 @@ static inline struct file * fcheck_files(struct files_struct *files, unsigned in
struct fdtable *fdt = files_fdtable(files);
if (fd < fdt->max_fds)
- file = rcu_dereference(fdt->fd[fd]);
+ file = rcu_dereference_check(fdt->fd[fd], rcu_read_lock_held() || lockdep_is_held(&files->file_lock) || atomic_read(&files->count) == 1);
return file;
}
--
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