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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@zeniv.linux.org.uk>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
LKML-Reference: <1266887105-1528-8-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Paul E. McKenney 2010-02-22 17:04:52 -08:00 committed by Ingo Molnar
parent 497f0ab39c
commit 7dc5215798
4 changed files with 14 additions and 4 deletions
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2
fs/file.c
View File

@ -478,7 +478,7 @@ int alloc_fd(unsigned start, unsigned flags)
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);
}

2
fs/proc/array.c
View File

@ -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);
}

6
fs/proc/base.c
View File

@ -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;

8
include/linux/fdtable.h
View File

@ -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;
}